For advanced civil engineering structures a service life of hundred up to hundred fifty and even two hundred years is sometimes required. The prediction of the performance of concrete structures over such a long period requires accurate and reliable predictive models. Most of the presently used, mostly experience based models don't have the quality and reliability that is required for reliable long-term predictions. The models designers are searching for should be based on an accurate description of the relevant degradation mechanisms. The starting point of such models is a realistic description of the microstructure of the concrete. In this presentation the need and the role of fundamental microstructural models for predicting the performance of concrete structures will be presented. An example will be given of a microstructural model with a proven potential for long-term predictions. Besides this also the role of models in general, i.e. in the whole design and execution process of concrete structures, will be dealt with. Finally recent trends in concrete research will be presented, like the research on self-healing cement-bases systems.

This article summarizes tests conducted on two full-scale interior slab-column connections with and without partially debonded reinforcement subjected to cyclic loading. Each test specimen consisted of a 4.2m square slab with a 355mm square column protruding 1.5m above and below the slab. The slab thickness was 152mm. The specimen with partially debonded reinforcement exhibited more lateral drift capacity than did the specimen with fully bonded reinforcement. With partial debonding of the flexural reinforcement, cyclic load appeared to produce less damage to the connection in the vicinity of the slab-column joint region.

A flat plate-column connection is susceptible to brittle punching shear failure, which may result in the necessity of shear reinforcement. In previous, experimental tests were performed to study the capacity of slab-column connections strengthened with various shear reinforcement, and the capacity of the specimens with lattice reinforcement are superior to the others. In present study, to study for effects of details of lattice reinforcement, experimental studies was performed. Main parameters are the amount of lattice shear reinforcement, arrangement of lattice and the effect of flexural re-bar. And capacity of the specimen with small amount of lattice reinforcement was higher than the capacity of other shear reinforcement.

In recent, there are a lot of problems such as shortage of construction workers, complicate progress of work and so on under RC construction. To solve these problems, the construction methods without form-work are used in the main structural members - beam, slab and stairs. However, there isn't yet form-workless system for columns. The purpose of this study was to experimentally evaluate the structural behavior of full scaled no-form system columns reinforced with steel sheet forms and angles. The main variables are 1) comparison of concrete member strength with and without reinforcement, 2) effect of L-angle.

In general, post-installed dowel bars are used as a shear connector to ensure the composite actions between new slabs and existing slabs in an apartment remodelling constructions expecially for enlarging the interior space outward the existing buildings. But, it has not been checked that the connection performance between existing and new slab is satisfactory not only for the structural safety condition but also the for serviceability and dwelling requirements. In this research, an experimental works were presented to evaluate the load transfer capacity for the planar joints between existing and new slab. The existing slabs were obtained from the existing apartment housing which will be demolished, and were retrofitted with carbon fiber plate. Test results showed that the planar joints with post-installed dowel bars behaved in full composite modes until ultimate capacity of test specimens, so sufficient ultimate and serviceability performance are confirmed.

Different from new or reconstruction of an apartment housing, the structural safety in the remodelling construction can be obtained through the repair and strengthening process based on the safety diagnosis and evaluation of structural performance. In this study, structural performance of existing members such as, reinforced concrete slabs, beams and columns are investigated through experimental tests. The structural members were obtained from the existing apartment housing which will be demolished. Test results showed that most specimens have a sufficient structural capacity except for some special case, for example, specimens with severe cracks or concrete loss due to improper casting. This same severe deteriorated or defective structure members originated from bad concrete casting or careless construction process should be repaired and strengthened before an remodelling construction.

The purpose of this paper is to investigate the structural behavior of fire damaged high-strength SRC columns with polypropylene fiber. When high-strength concrete is exposed to high temperature, spalling is occurred then it leads to decrease the capacity of members. Polypropylene fiber is used to reduce the spalling of the specimens and the distinction in the behavior after fire is observed. High-strength concrete specimens were exposed to high temperatures by the ISO 834 curve. Main experimental parameters were the ratio of the contained polypropylene fiver, heating time and type of loading. Reduction rate in residual strength and stiffness is observed for the mixing of PP fiber, the heating time and eccentricity of loading.

In this paper, long term deflection of RC beam with variable substitution ratio of recycled aggregate is investigated. 6 RC beam specimens are designed using concrete made of coarse aggregate of 25mm size, mix strength of 21MPa, slump of 12cm and air content of $5.0{\pm}1.5%$. A few concrete blocks are made and used for long term loading. The loading and deflection instrumentation are conducted following the process codified in ACI 318-05 code. Test result shows that the deflection of specimens depends on the compressive strength of concrete. And it is concluded that the deflection of RC beam can be predicted like normal beam using ACI formula if certain level of compressive strength is acquired even recycled aggregate is used in making the beam.

Increase in use of deck plates is accelerated by a manpower shortage and the high cost of construction. Some of problems including fire resistance, waterproof, and low corrosion can be solved by development of new deck plates. This paper evaluates the structural performance of the LAMO Deck which metal laths instead of galvanized steel sheet is covered by mortar.

This study is to evaluate flexural behavior of RC beam with different types of coarse aggregates, so called natural or recycled aggregate. Two reinforced concrete beams were manufactured with different replacement level of recycled coarse aggregates : Concrete made with 0% of coarse aggregates, concrete made with 100% of recycled coarse aggregates. From the test, the general flexural performances of RC beams with different types of coarse aggregates such as cracking moment, crack patterns, maximum moment/crack width are discussed.

Unlike columns having lap-spliced longitudinal bars in plastic hinge regions columns having 50% of lap-spliced bars were reported to have good ductilities relatively. But the effect of transverse reinforcements to deformability is not clearly confirmed. In this study scale models with different confinements were tested under various loading conditions. It was confirmed that deformability was increased with increase of transverse reinforcement ratio regardless of loading conditions and 75% of confinement yielded the satisfactory deformability.

Due to the bond failure of lap-spliced longitudinal bars very brittle failure is conducted in existing RC columns. This failure can be, however, prevented by providing partial lap spliced longitudinal bars. But the deformability of columns having various lateral confinements is not confirmed yet. In this study scale models with different confinements were tested to investigate characteristics of seismic behaviors. It was confirmed that deformability was increased dramatically with increase of lateral reinforcements.

In reinforced concrete structures, moment redistribution which can be caused as a result of plastic behavior of reinforcing bars in continuous beams and slabs, are recognized as favorable phenomenon, for it elevates the flexibility and efficiency in member and reinforcement design. To obtain detailed information of the concrete-reinforcement bonding effect on the moment redistribution of continuous beams, tests have been planned and carried out for six specimens, the positions and extents of the bonding area being taken as experimental parameters.

A common form of construction for apartment buildings consists of walls and coupling element. But, the structural behavior of coupling element are very complex and affected by the properties of coupling element. The propose of this paper is to evaluation the behavior of coupling element in wall-dominant system. An 1/2 scale three specimens was constructed and under cyclic loads. The specimen was consisted of opening walls and coupling element as well as floor slabs. From the result of this study, in coupling slabs, the stresses were not uniform across the width. And the effective width of coupling slabs was found smaller than the that of predicted from previous studies.

This study is aimed to investigate the strength variation of fire-damaged reinforced concrete column with polypropylene by non-destructive test. It is studied to infer the recovery degree of residual strength of fire-damaged concrete. For measuring the surface hardness of RC columns, Schmidt hammer test is used. Testing is performed four-times: before fire test, directly after fire test, after 30 days and after 4 months.

The objective of this study is to find out the shear capacity of URM wall and the variables that affect the shear capacity of URM wall such as the opening and the aspect ratio, considering four kinds of failure modes, sliding shear failure, toe crushing failure, and diagonal shear failure. The main varialble is the shape of opening of URM walls. First URM has one door, second has one window, third hase one door and one window, the last has two windows. The test results of URM with openings show that the specimens are governed by rocking failure mode.

The shape and dimension of precast concrete structure used in habor construction(caisson, block, etc.) are considered productive facility abilities, demanded minimum dimension in work of each member, the relation between the depth of water and a location of leaving, work conditions of towing and leaving, after leaving, differential settlement, etc. As this study examined friction resistance effect of financially designed precast concrete structure formed convex in bottom and stone mound.

Longitudinal reinforcements of the plastic hinge region were behaved tensile deformation and compressional deformation by direction of lateral loading. However Confinement steels were behaved only tensile deformation by lateral loading. Transverse steels were laid the state of tension in the lateral loading of time, and they were laid state that stress is zero when it was removed lateral load. Nine specimens were tested under cyclic stresses(tension and zero). The purpose of this research is to investigate the strain behavior and capacity of energy for confinement steel. The selected test variables are $L/d_b(L/d_b=6)$, size of reinforcement and specified yielding strength(300, 400, 500 MPa).

The purpose of this study is to investigate the inelastic behavior of hollow reinforced concrete bridge piers under varying axial load. The role of the variable axial load is very important in the ductility, strength, stiffness, and energy dissipation. A computer program, named RCAHEST(Reinforced Concrete Analysis in Higher Evaluation System Technology), for the analysis of reinforced concrete structures was used. Material nonlinearity is taken into account by comprising tensile, compressive and shear models of cracked concrete and a model of reinforcing steel. The proposed numerical method for the inelastic behavior of hollow reinforced concrete bridge piers under varying axial load is verified by comparison with reliable experimental results.

This paper deals with shaking table tests on RC piers to evaluate the seismic performance under near fault motion. Small scale models were fabricated and axial force was applied by introducing prestress at the centroid of the column section. Mass effect of the superstructures was simulated by mass frame which was linked with a pier model by steel bars because of the limited payload of shaking table. Friction of the mass frame when it moves was minimized by special details and it was proved before tests. Scale factor of the RC piers was 4.25. Main parameters of the test were details of reinforcements. After verifying the results of shaking table tests, seismic performance was evaluated by increasing the acceleration of the near fault motion.

In order to achieve target ductility the stress-strain relation of confined concrete is indispensible. In this study the specimens with different transverse reinforcement ratios were tested. The test results were compared with empirical equations and the characteristics of confinement effect were investigated.

This study represents results of performance-based fragility analysis of reinforced concrete (RC) bridge. Monte carlo simulation is performed to study nonlinear dynamic responses of RC bridge. Two-parameter log-normal distribution function is used to represent the fragility curves. These two-parameters, referred to as fragility parameters, are estimated by the traditional maximum likelihood procedure, which. is treated each event of RC bridge pier damage as a realization of Bernoulli experiment. In order to formulate the fragility curves, five different damage states are described by two practical factors: the displacement and curvature ductility, which are mostly influencing on the seismic behavior of RC bridge piers. Five damage states are quantitatively assessed in terms of these seismic ductilities on the basis of numerous experimental results of RC bridge piers. Thereby, the performance-based fragility curves of RC bridge pier are provided in this paper.

This study performed numerical analysis for obtaining optimal frequency and damping ratio of tuned mass damper (TMD) using 20 seismic loads measured at rock site. The structures of $1{\sim}2$ second natural period were considered, and optimal frequency and damping ratio were estimated for different mass ratio in terms of displacement and absolute acceleration response control. Numerical results showed that the values of the optimal parameters were different those from previous study by Hartog.

In the past study, the fragility curve for the evaluation of earthquake resistance and earthquake-related damage of concrete bearing wall structures were studied. The fragility curve represents the probability of being in or exceeding a given damage state such as Slight, Moderate, Extensive or Complete structural damage state, and is defined as a cumulative lognormal distribution. Each fragility curve is characterized by median and lognormal standard deviation values. We performed parametric pushover analysis for typical 12 and 24 stories apartment buildings. Based on the results, the fragility curves of concrete wall structures were standardized. Using the fragility curve, engineers can directly evaluate the probability of a damage state to a spectral displacement of interest.

Current ACI and AIJ guidelines only address the importance of the concrete strength and geometry of the joint. There are no significant attention paid to other variables. In addition, the current design code doesn't predict the ductility of the beam-column assemblies. The former researcher proposed the analytical model to predict the shear strength of the joint panel as well as the ductility of the beam-column assemblies in year 2004. In this study, the experiments to investigate shear behavior of reinforced concrete beam-column joints and to verify proposed model were carried out, based on the experimental results. As the formal researcher proposed, the factor K (K=0.5), the ductility of BJ-failure was predicted reasonably when the transverse reinforcement ratio exceeded 0.0186. However, the proposed equation showed a large discrepancies in the ductility estimating when transverse reinforcement ratio was below 0.0186.

In this study, an approach that installs seismic isolation bearings was proposed for the seismic retrofit of the existing bridges. The method that replaces all existing bearings with seismic isolators was proposed already. However, in this study, we recommend to utilize the existing bearings for the benefit of safety and cost. According to our proposal, the seismic isolators do not support vertical loads but they just function as the period shifter and the horizontal damper. To verify this approach experimentally, the real scale bearings and isolators for the real highway bridges were designed and fabricated. And the responses of this isolated bridges to the assumed earthquakes were determined by the pseudo dynamic test scheme. The test results were also compared to the responses computed by the well known structural analysis software to check the reliability of the test. From the test results, we found that the retrofitted bridges using the proposed method showed stable performances under earthquakes.

In this study, new bond-slip model is proposed. The proposed bond-slip model which has bilinear ascending regions and exponential descending region by modifying the conventional bilinear bond-slip model has been verified. Then, result by finite element analyses using interface element implemented with bond-slip model compared well with those of existing experiment researches on bond-slip models. It is shown that bond strength and effective bond length predicted by the bond-slip model and finite element analysis is good agreement with those of pull tests.

This study is for the strengthening method of continuous bridge through external tendon strengthening that is the most general and effective among concrete bridge's strengthening method. Recently, it is numerous that slab's parts between spans have continuity for improving trafficable ability. However, in this case, slab would have a crack; bridge's durability would be damaged, and also it is too difficult to manage and maintain bridge due to the tensile strength of negative moment. Therefore, the purpose of this study is to demonstrate load-carrying through experiments and develop new external pre-stressing strengthening method for reinforcing continuous bridge.

This study focuses on the flexural behavior of RC beam with externally bonding FRP reinforcement. FRP-plate strengthening system is mainly installed with an anchor-bolt. But the installation with it has several disadvantage as a complicated work, a high labor costs. To complement these disadvantage, the test is performed about improved FRP-plate strengthening system.

Many research have been carried out concerned with the flexural performance of FRP composite in a various ways. Most of them, however, have used a small-scale specimen, so haven't been fully verified by full-scale model test. In this study, a full-scale RC beam model test for flexural strengthening with CFRP composites has been performed in order to verify test results obtained through a series of small-scale model test with respect to FRP stiffness affecting strengthening performance in the previous studies. A total of 4 specimens have been manufactured including control beam. The specimens strengthened with CFRP composites consist of 3 different CFRP stiffness with 2 types of CFRP composite. Consequently, the purpose of this study is to estimate influence of the size effect of specimens and FRP stiffness on the flexural performance. As a result, the effective strain of FRP composite is inversely proportional to FRP stiffness and ensures the same performance with small-scale model test.

It is generally reported that most of RC beams strengthened with simply bonded FRP composite is failed by FRP debonding. Also, the flexural performance of RC member strengthened with FRP composite can be calculated using the effective strain of FRP. The effective strain as a result of the debonding failure depends on many variables, such as FRP stiffness including the thickness($t_f$) and modulus of elasticity($E_f$), the amount of FRP but the FRP stiffness is reportedly the most influential. The purpose of this paper, therefore, is to examine effects of FRP stiffness on the flexural strengthening of RC beams. 4 different stiffness of CFRP composite including CFRP sheet and laminae were selected. From the tests, it was found that the flexural performance of RC beams strengthened with CFRP composite can be calculated based on the effective strain of the CFRP composite and the effective strain is inversely proportional to the CFRP stiffness.

The main purpose of this study is to develop a Sprayed FRP repair and strengthening method, which is a new technique for strengthening the existing concrete structures by mixing carbon or glass shot fibers and the epoxy or vinyl ester resins with high-speed compressed air in open air and randomly spraying the mixture onto the concrete surface. At present, the Sprayed FRP repair and strengthening method using the epoxy resin has not been fully discussed. In this study, a series of experiments are carried out to evaluate the strengthening effects of the flexural and shear concret beams strengthened with the Sprayed FRP method. The results revealed that the strengthening effects of the flexural and shear specimens are similar, compared to those of the FRP sheet.

In this study, a seismic performance of reinforced concrete columns strengthened by a sprayed fiber reinforced polymer (SFRP) is investigated. For this purpose, six column specimens approximately scaled into 2/3, are designed and tested under a constant axial load, 10% of the nominal axial strength of column, and pseudo-static reversed cyclic lateral loading system. Four specimens are strengthened by Sprayed FRP using different combinations of short fibers (carbon or glass fiber) and resins (epoxy or vinyl esther). For comparison, the test investigated in this study also includes a specimen strengthened using carbon fiber reinforced polymer (CFRP), and also a control specimen without strengthening. The results revealed that specimens strengthened using SFRP showed a improved structure behavior, compared to control specimen, in terms of strength, ductility, lateral drift capacity, and energy-absorbtion capacity. In addition, compared to the specimen strengthened using CFRP, Sprayed FRP-strengthened specimens reasonably showed a equivalent seismic performance.

The main purpose of this study is to develop a Sprayed FRP repair and strengthening method, which is a new technique for strengthening the existing concrete structures by mixing carbon or glass shot fibers and the epoxy or vinyl ester resins with high-speed compressed air in open air and randomly spraying the mixture onto the concrete surface. At present, the Sprayed FRP repair and strengthening method using the epoxy resin has not been fully discussed. In order to investigate the material property of Sprayed FRP, this study carried out tensile tests of the material specimens which are changed with the combinations of various variables such as the length of shot fiber and mixture ratio of shot fiber and resin. These variables are set to have the material strength equal to one layer of the FRP sheet. As a result, the optimal length of glass and carbon shot fibers were derived into 3.8cm, and the optimal mixture ratio was also deriver into 1:2 from each variable. And also, the thickness of Sprayed FRP to have the strength equal to one layer of FRP sheet was finally calculated.

Near surface mounted (NSM) is a recent strengthening technique based on bonding fiber reinforced polymer (CFRP) bars (rods and laminate strips), the use of NSM FRP bars is Emerging as a promising technology for increasing flexural strength of deficient concrete. In order for this technique to perform effectively, the structural behaviour of RC element strengthened with NSM FRP bars to be fully characterized. Totally, 10 beams were tested using symmetrical two-point loads test. The parameters examined under the beam test were a diffrent type of strengthening length.

Serviceability of reinforced concrete building is affected dominantly by long term deflection of slab. And in case of reinforced concrete building with flat plate slab, severe long term deflection was expected because it has no beams which have large flexural stiffness. Therefore it is important to calculate exactly long term deflection of RC flat plate structure to assure its serviceability. However, current codes couldn't calculate exactly long term deflection of RC flat plate structure because they don't consider effects of boundary condition and construction load. By the way, recently the method to calculate long term deflection of RC flat plate structure was proposed by considering these effects. In the present study, long term deflection of RC flat plate structure was analyzed by comparing this method with recent experimental results. In conclusion, long term deflection of RC flat plate structure was affected considerably by effects of boundary condition, construction load and tensile strength of concrete. And recently proposed method considers these effects reasonably but it should be modified to reflect creep effect of RC flat plate slab reasonably.

This paper presents an analytical results on limits of debonding failure for RC beams strengthened with near-surface mounted(NSM) CFRP strips. An analytical model was derived to predict the failure mode and the maximum load. An analytical model has two assumptions. The first is that the debonding failure occurs at the epoxy-concrete interfaces. The second is that the debonding failure occurs at the end of the FRP reinforcement due to concentration of shear stress. Results of the comparison of existing test data and analytical model data have predicted the failure mode and the maximum load well. Also, this paper proposed limits of debonding failure to prevent the debonding using the strengthening area and the groove depth.

Carbon fiber reinforced polymer (CFRP) laminates can be used more efficiently in strengthening applications by applying prestress to the CFRP laminates. A key problem for prestressing with CFRP laminates is anchoring the laminates. These may include fracture to the CFRP laminates due to excessive gripping force or slippage of the CFRP laminates out of the anchorage zone caused by low friction between the anchor device and the lamiantes. The main objective of this study is the development of an applicative wedge-type anchorage system for prestressed CFRP laminates through experimental study. The experimental parameters were the type of anchorage and the effect of elastic modulus of tab. The test results showed that the developed anchor assures 100% CFRP laminate strength.

Carbon fiber reinforced polymer(CFRP) strips have superior mechanical and chemical properties in comparison with conventional materials. The purpose of this study is to investigate the mechanical shear behavior of concrete structures strengthened by CFRP strips A total of 15 concrete members were made and tested. Shear span to depth ratio(a/d) and the spacing of CFRP stripswere selected as major test variables. From test results, it isshown that shear strengthening with CFRP strips can increase the first shear strength and ultimate shear strength of concrete members significantly. And the brittle shear failure mode can be changed to a ductile failure mode by CFRP strips.

Carbon fiber reinforced polymer(CFRP) have superior mechanical and chemical properties in comparison with conventional materials. And post-tensioning method has been used for structural reinforcement of RC structures due to easy installation and good effect of resisting capacity of structures. But the higher cost of CFRP and the loss of prestressing force with time are considered the major problems to use it. In this study, CFRP Strips and external post tensioning for rehabilitation of old concrete structures were adapted and optimal combination of these methods is considered. A total of 17 concrete members were made and tested. The types and numbers of CFRP strips and post-tensioning types were selected as major test variables. From test results, it is shown that the concrete members that post tensioned and bonded CFRP strips has a pronounced effect on the strength and deformational behavior. This present study indicates that external temporally post tensioning can reduce the amount of CFRP strips required and the combination of temporally post tensioning and CFRP strips may meet the strength and ductility requirements of old structures.

Wall construction apartment built before 1988 years need internal examination reinforcement according to existing laws ans regulations at remodeling because do not earthquake resistant design. Established newly wall to interest paid back at the same time a the principal direction for wall construction apartment internal examination reinforcement, and satisfied internal examination standard because uses width displacement between floor. This study analyzes displacement value such as latitude and presented position of efficient reinforcement wall and wall quantity at earthquake resistant design of wall construction apartment.

The one of the commonly reported failure mode of the RC beam strengthened with FRP was caused by the separation of the concrete cover, so called delamination. Therefore, ACI440 recommended that concrete cover delamination can be prevented in strengthened beams if bond length of FRP composite be exteneded over a point of cracking moment. In this study, the failure mode and the flexural performance of RC beam with different bond length of FRP are estimated. Each bonded length is calculated based on the point of cracking moment with addition or subtraction of specific length(=150mm). The results of this study show that mid-span debonding occurs in the specimen strengthened with CFRP strips which are bonded over the point of cracking moment, while concrete cover deliamination occurs at the termination point of CFRP in the specimen with less bonded length than the point of cracking moment region.

Experimental study has been performed in order to evaluate the effects of steel reinforcement ratio on the flexural behavior of RC beams strengthened with CFRP sheets. The steel reinforcement ratio of $0.78%({\rho}_s/{\rho}_b=24%)$ is selected to have balance failure when control RC beams were strengthened with 1 ply CFRP sheet. Total 6 half-scale specimens were manufactured including each unstrengthened specimens, which have 3 different reinforcement ratios. The specimens strengthened with CFRP sheet consist of under- or over-reinforced beams for the balanced failure condition. Moreover, the behavior of un strengthened or strengthened beams were compared to evaluate flexural performance. The results of this study show that the over-reinforced specimens were failed by concrete crushing prior to CFRP sheet failure by debonding or rupture. On the contrary, the under-reinforced specimen were failed by rupture of CFRP sheet.

In this investigation, fracture mechanism of the pre-cracked beams strengthened with FRP-Rod and GSP(Glass Fiber-Steel Plate) were experimentally studied by the repeating load test according to the three different loading speeds. In the experiments, it was identified that pre-crack in the damaged beams led the significant fracture type of the strengthened beams and loading speed did not influence the behaviors of the fractures. On the other hand, strengthened beams by GSP have more large increasing effects of the strength comparing to beams strengthened with FRP-Rod, but they have a brittle behaviors in fracture.

Recently, an improved capacity for RC bridges is required by their deterioration or necessary to carry traffic increase. Strengthening is known as a better way to improve capacity of bridges than reconstructing. Fiber Reinforced Plastics (FRP) is introduced as one of the best strengthening structures in this paper. It is also known as an economical improvement. Therefore, FRP sheet and Glass Fiber-Steel Composite Plate (GSP) in this research were used in strengthening slab of RC bridges. Experimental data from the strengthening will be helpful to better understand the slab behavior and an effect of the strengthening.

Following the evaluation of the irrigation & drainage structure, a suitable repair and reinforcing procedure can be selected based on this report. Successful procedures take into account the causes of the crack. This provides a survey of crack repair methods, including a summary of the characteristics of the cracks that may be repaired with each procedure, the type of irrigation & drainage structure that have been repaired and a summary of the procedures that are used. Readers are also directly contacted to the website(http:/rri.karico.co.kr/rricon). This report is intended to support the purposes, philosophy, and needs, using easily understood graphics and photos from the construction fields. The results of this study will be distributed to the public official in technical post, the operator in construction site and the member of Korea Agricultural & Rural Infrastructure Corporation and etc.

Unlike external bonded plate or carbon fiber, the external unbonded strengthening has some advantages in speed and simplicity of installation. It is not required surface preparations and not affected by environmental conditions. A set of six laboratory tests on RC beams strengthened using the technique are reported, results compared with non-strengthened specimens. The main test parameters are the cross-sectional area of the high-tension bar and the distance of stirrups. Test result show that the beams reinforced are superior to reference specimens, especially for the strength and deformation capacity. Also, it is shown that good efficiencies can be achived in shear strength of the beam.

The bond characteristics of three different types of glass fiber reinforced polymer(GFRP) reinforcing bars with different surface deformations were studied experimentally. Each specimen consisted of a concrete prism, 150 by 150 mm on each edge, with the longer axis in the vertical direction. Two rebars were embedded in each specimen, perpendicular to the longer axis and parallel to and equidistant from the sides of the prism. In vertical direction, one rebar was located at 75 mm from the bottom of the prism, and the other 225 mm from the bottom. All testing procedures including specimens preparation, set-up of test equipments and measuring devices were made according to the recommendations of CSA Standard S806-02.It was found that the bottom reinforcements showed higher bond stress than that of the top rebars.

The shear resistance of RC beams is subject to the amount of shear-reinforcing bars ($p_w$) and yield strength ($f_{wy}$) as well as their interactive influence ($p_wf_{wy}$). Thus, it is reasonably expected that high-strength steel bars can greatly reduce the necessary amount of shear-reinforcing bars. On the other hand, although the bond strength is influenced by the amount of shear reinforcing bars, it is not affected by the yield strength. Thus, there is often an issue that bond failure occurs before shear failure depending on the arrangement of shear reinforcing bars. It is a common practice to set sub-ties for the transverse confinement of the main re-bars as a method to prevent the bond failure. However, it can also become a factor in decreased work efficiency due to the complexity of the construction. This study experimented with simultaneous use of high-strength transverse reinforcing bars ($f_{wy}=800MPa$) and U-shaped transverse reinforcing bars of regular strength ($f_{wy}=300MPa$) in an attempt to decrease the necessary quantity of shear reinforcing bars. The effect of this attempt was investigated through fundamental experimental research in terms of the improvement in shear resistance and bond strength as well as the ease of construction.

The use of Fiber Reinforced Polymer (FRP) bars has been gaining popularity in the civil engineering community, as an alternative material to steel reinforcement, for their noncorrosive nature and high strength-to-weight ratio. Good performance of reinforced concrete requires adequate interfacial bond between the reinforcing material and the concrete because the load applied must be transferred from the matrix to the reinforcement. Although studies on the FRP bond behavior under monotonic loading has been reported by many, there are very little work done under cyclic loading. In this paper, we present the experimental study on the bond behavior of three different types of FRP rebars subjected to four different cyclic loading conditions.

Bond between reinforcing bar and surrounding concrete is supposed to transfer load safely in the process of design of reinforced concrete structures. The effects of defomation properties on bond of reinforcing bars to concrete are studied. Beam-end tests are used to investigate the effects of machining of bars in addition to rib angle and relative rib area. The test results show that bond strength of machined bars were higher than the conventional bars produced in factory. Higher rib height bars with rib angle $30^{\circ}{\sim}60^{\circ}$ showed higher bond strength than lower rib height bars with low angle.

The designer has difficulty due to inadequacy of provisions in the domestic design code and lack of understanding for behavior of D-region. The reinforced concrete pi(${\pi}$)-shaped RC rahmen bridge consists of various failure mechanisms as the crushing or splitting from compression concrete, and shearing failure under the loading plate. However, predicting those failure mechanisms is very difficult. In this study, the pi(${\pi}$)-shaped RC rahmen bridge is analyzed and designed by using strut-tie model. Adequacy for the application of strut-tie model is verified by comparison with the way used in current design practice. As a result that designing the structures should be maked a comparison between strut-tie model and current conventional design method.

In this paper Satisfaction Curve has been applied to estimate the material safety by using Bayesian Method based on given parameters which are obtained from experimental results of other researchers. From the results, Bayesian Method is proven to be an available method for safety estimation of material.

For structural engineers, design of pile cap causes difficulties since design of this member is not specifically addressed by codes. In general, pile cap is considered as deep beam and designed for shear and moment at specified critical section. This is called as traditional section method. However, many international design codes suggest the application of strut tie method for better design of this member. In this paper, a brief application of strut tie method to the design check of pile cap structure designed by section method is presented. Unlike well known pile cap with single column, the example pile cap has two columns. In order to find out proper load path under various load condition, three dimensional finite element method was carried out. The result indicates that provided reinforcement by traditional section method has sufficient capacity to meet the design requirements.

Fast construction of bridge structures is a new trend of bridge design. Accelerated bridge construction includes the construction of superstructures and substructures. In order to reduce the construction time for substructures, precast prestressed bridge piers are increasingly applied in other countries. One of the main concern in the design of precast piers is the determination of the axial prestress forces. The behavior of the piers should be investigated under service loadings and ultimate conditions. In this paper, the magnitude of prestress is calculated to control the stress at the joint of precast piers. Considering long-term behavior of prestressed piers, P-M diagrams for precast piers are obtained to verify the ultimate behavior of the piers. Based on these studies, precast piers are applied to the light-railway bridge piers.

The HPFRCCs show that the multiple crack propagation, high tensile strength and ductility due to the interfacial bonding of the fibers to the cement matrix. Moreover, performance of cement composites varies according to type and weight contents of reinforcing fiber. and HPFRCCs with hybrid fiber have better performance than HPFRCCs with single fiber in damage tolerance. Total four cylindrical specimens were tested, and the main variables were the type and weight contents of fiber, which was polyvinylalchol (PVA), polyethylene (PE). In order to clarify effect of hybrid types on the characteristics of fracture and damage process in cement composites, AE method was performed to detect micro-cracking in HPFRCCs under cyclic compression. Loading conditions of the uniaxial compression test were monotonic and cyclic loading. And from AE parameter value, it is found that the second and third compressive load cycles resulted in successive decrease of the amplitude as compared with the first compressive load cvcle.

This study presents a technique to quantitatively measure the corrosion level of a reinforcing bar using the infrared thermography system. The temperature-distribution of the concrete surface is monitored and the temperature change of the reinforcing bar is analysed in terms of corrosion level and concrete cover depth. The experimental results indicate that temperature increase of the reinforcing bar is significant when the corrosion level is high, which implies that the quantity of heat is strongly dependent on corrosion level. Also, as the concrete cover depth of the specimen and the atmosphere temperature increase, the temperature variation becomes small.

Almost 30 years have been passed since the first nuclear power plant was operated in Korea. Many studies have been actively conducted from the early 1990's in order to develop the deterioration management system for concrete structures in NPPs(Nuclear Power Plants) accordingly. Base on these studies, a systematic deterioration management program has developed and operated since 1997. According to this program, systematic inspections to provide database and evaluation were periodically performed (every overhaul at intervals of $12{\sim}18$ month and every five years). Accumulated deterioration database was usefully utilized for the NPP PSR (Periodic Safety Review). In this paper, the long-term durability and integrity of Kori 1,2 NPP concrete structures which are the oldest ones in Korea were evaluated based on the precise inspection database and regulatory inspection results including compressive strength, depth of carbonation, amount of chlorination and spontaneous potential of reinforcing bar, etc. It was noted that Kori 1,2 NPP structures have not any serious durability problems.

It is essential to develop a large capacity, non-contact nondestructive inspection system having high reliability to investigate repaired and strengthened structures. Nowadays, an infrared camera is widely used in non-contact nondestructive inspection system. Because an infrared camera is sensitive to the surrounding environment, it is necessary to improve a sensitivity of thermal image information and a relationship between defects and thermal image information. In this papaer, presented is an optimum void detection chart for the optimum conditions to detect infrared rays from inside and outside defects like voids and cracks in concrete structures using extensive computer simulation. Sensitivity studies are performed with respect to variables influencing the temperature distribution such as heating temperature, heating time, and geometries of defect, etc. It may be stated that it could be successfully utilized for the non-contact nondestructive inspection system to detect defects in concrete structures.

The objective of this study is to take the first step in creating a user-friendly health monitoring system for recycled aggregate concrete structure using acoustic emission(AE). Each specimen was a cube, the edge of which was 150mm. For pull-out tests, a steel rebar, 13mm in diameter, was embedded in the center of each specimen and casting directions(i.e., vertical and horizontal) were considered in this paper. The AE parameters were analyzed for damage levels(i.e. internal cracking stage, pull-out stage) of all specimens. Results from this study show that event, duration versus amplitude of a signal, showed a clear difference for different loading stages depending upon the concrete casting directions.

When concrete is subjected to uniaxial compression, the failure process is normally initialed from a localized zone. The localization of failure governs structural behaviors of concrete. In this paper, the compressive strength and failure behavior of recycled coarse aggregate concrete with different replacement level of recycled coarse aggregates are investigated using acoustic emission(AE). AE characteristics of concrete were investigated during the entire loading period. For these purpose, four recycled coarse aggregate replacement level (i.e 0%, 30%, 60% and 100%) were considered in this paper. Result from this study show AE signal, AE method can apply to investigate a compressive failure mode according to recycled coarse replacement level.

The HPFRCCs show the multiple crack and damage tolerance capacity due to the interfacial bonding of the fibers to the cement matrix. For practical application, it is needed to investigate the fractural behavior and of HPFRCCs and understand the micro-mechanism of cement matrix with reinforcing fiber. The objectives of this paper are to examine the compressive behavior, fracture and damage process of HPFRCC by acoustic emission technique. Total four series were tested, and the main variables were the hybrid type, polyethylene (PE) and steel cord (SC), and fiber volume fraction. The damage progress by compressive behavior of the HPFRCCs is characteristic for the hybrid fiber type and volume fraction. And from acoustic emission (AE) parameter value, it is found that the second and third compressive load cycles resulted in successive decrease of the ring-down count rate as compared with the first compressive load cycle.

Coupled shear walls consist of two or more in-plane walls inter-connected with coupling beams. In order to effectively resist seismic loads, coupling beams must be sufficiently stiff, strong and posses a stable load-deflection hysteretic response. Much of requirements to the civil and building structures have recently been changed in accordance with the social and economic progress. Ductility of high performance fiber reinforced cementitious composites(HPFRCCs), which exhibit strain hardening and multiple crackling characteristics under the uniaxial tensile stress is drastically improved. This paper provides background for design guidelines that include a design model to calculate the shear strength of pseudo strain hardening cementitious composite steel coupling beam.

Deformability of RC members in shear after flexural yielding is limited and controlled by governing failure modes and material strength. Shear strength of members in D-regions has been explained by a direct load path (direct strut or arch action) and indirect load path (fan action or truss action). Indirect load path including truss action and fan action rely on bond along tension ties. Generally, superposition of two actions results in total shear strength when shear failure modes control. The ultimate deformation depends on controlling failure modes and thereby, their force transfer patterns. Proposed models are capable of explaining of limited deformability of RC members in D-regions.

Recently, many design standards recommend the use of a strut-tie model approach for design of structural concrete with D-region(s). However, since the design standards of the conventional strut-tie model approaches are suggested on the assumption of using a determinate strut-tie model, it is difficult to apply an indeterminate strut-tie model in the design of continuous deep beams. In this study, an indeterminate strut-tie model for continuous deep beams is proposed to resolve the problem, and the ultimate strengths of 35 continuous deep beams tested to failure are evaluated for the validity check of the proposed indeterminate strut-tie model. The analytical results by the proposed model are compared with those by the conventional approaches of ACI 318-99 and ACI 318-05.

The anchorage zone of prestressed concrete members is a critical region where a large concentrated force due to prestressing by tendons is introduced. In this study, the ACI, AASHTO LRFD, CEB-FIP design criteria and the nonlinear strut-tie model approach are applied to the ultimate strength analysis of simple anchorage zones of 18 post-tensioned concrete members tested to failure. From the result of ultimate strength analysis, the advantages and disadvantages of each method are compared and discussed.

This paper presents shear deformation characteristics in reinforced concrete beams. Based on the relationship between shear and bending moment in beams subjected to combined shear and bending, the behavior of a beam is explicitly divided into two base components of the flexural action and the tied arch action. Transverse elongation of the web and deflections are calculated from shear compatibility condition in a beam and compared with test results.

This paper deals with the shear deformation charateristics of concrete beams strengthened with steel/FRP Bar. Applying the shear behavioral model based on shear deformation compatibility to RC beams tested by Ahmed K. El-Sayed et al.(2006), their transverse deformation in the web are calculated at ultimated loads after decoupling the shear carried by arch action in each beams. The calculated transverse deformation at ultimated loads are nearly same for the different reinforcement ratio. From these results, the temporary transverse deformation limit criterion is deduced. Using the proposed temporary limit criterion, the shear strength of concrete beams strengthen with FRP Bar tested by Ahmed K. El-Sayed et al.(2006) is predicted. These predicted values are compared with the measured values and the results are also compared with the current ACI and JSCE equation. The proposed method predicts the ultimate shear capacities more accurately than the equation of ACI and JSCE code. The predictions by the ACI and JSCE code are founded to be very conservative.

ASCE-ACI Committee 426 and 445, on Shear and Torsion, well noted in their report that recent research work regarding shear and torsion had been devoted primarily to members. But it was not logical approach of PSC members applied by axial force based on the shear deformation in web element. And it was not included that the effect of axial is to shift the shear strain(or crack width) in the web element versus the applied shear curve up or down by the amount by which the biaxial tension-compression state varies. The shear strength also increases or decreases, so that the change in shear strain at service load due to the presence of axial load is to some extent changed. Generally, in corresponding beams the shear strain at service load is less in the beam subject to axial compression and greater in the beam subject to axial tension, than in the beam without axial load. In particular, however, no research were available on the shear deformation in shear of PSC members with web reinforcement, subject to axial force in addition to shear and bending. Therefore, this study was basically performed to develop the program for the calculation of the shear deformation based on the shear effect of axial force in prestressed concrete members.

This paper provides a method to predict the ductile capacity of reinforced concrete beams that fail in shear after flexural yielding. The proposed method takes into account shear strength deterioration in the plastic hinge region of RC beams. The shear contribution of the concrete in the plastic hinge region decreases after flexural yielding of the beam due to a decrease in the effective compressive strength of the concrete. To verify the shear strength and the corresponding ductility of the proposed method, 8 RC beams were tested under reversed cyclic loading.

In this research, bending shear test of HPFRCC beams is conducted to obtain the shear strength of HPFRCC beams. Parameters are ratio of volume percentage of fibers. Also, the uniaxial tensile test of HPFRCC is conducted to obtain the tensile cracking stress of each parameters. From the uniaxial tensile test result, the shear strength of HPFRCC beams can be calculated by using the preexisting shear analysis model. Then, the shear strengths of bending shear test result and analysis result are compared.

The results and interpretations of push-out tests on shear connector devices for composite bridges carried out in this study are presented. The devices under investigations are headed studes, perfobond rib, ㄱtype perfobond rib, T- Connector and a new type of shear connector called T type perfobond rib. This new connector is flat steel plate with a number of holes punched through. The results obtained indicate that the T type perfobond rib shear connectors exhibit adequate ductility and substantially higher capacities. Therefore for composite beams utilizing reinforced concrete slabs, the T type perfobond rib shear connectors is a viable alternative to the headed studs.

One of main issues of the FRP-concrete composite member is shear connection between FRP and concrete in order to secure composite behavior of FRP and concrete. To solve this problem, perfobond rib FRP shear connector is introduced for the mechanical shear connection. In this study, experimental study was carried out on the perfobond rib FRP shear connectors in order to develop the effective details of perfobond rib FRP shear connectors. Pull-out test specimens were manufactured with FRP plate with holes embedded in concrete block. Main parameters considered in this study were diameter of holes, ratio of spacing between the centres of holes to the diameter of holes, and thickness of FRP plates. Test results are discussed according to above parameters compared with other empirical expressions for steel perfobond rib connector.

This study was performed to suggest a theoretical method of flexural capacity of 'Hybrid Beam'. Since the center of 'Hybrid Beam' is composed of embedded composite beam section, a theoretical method of embedded composite beam could be applied to estimation of flexural capacity of 'Hybrid Beam'. In this study, a theoretical evaluation method for flexural capacity of embedded composite beam, which is suggested by KBC 2005, is chosen and its applicability is evaluates as comparing theoretical results with experimental results. In results, for estimation of theoretical ultimate strength, it is proper method that both effects due to concrete and rebar are considered and whole section is assumed to be plastic. and for estimation of theoretical strength at yielding stste, it is proper to apply allowable stress design.

In this paper, the seismic performance of SRC piers for near fault motions was evaluated by shaking table tests on small scale models. Dead load of the superstructures was simulated by axial prestress at the center of the column section. A mass frame linked with steel bars was fabricated to include the effect of superstructure mass. Friction of the mass frame when it moves was minimized by special details and it was proved before tests. Five pier models with 400mm diameter were tested by increasing the acceleration of the near fault motion. Test results were discussed and compared with previous quasi-static tests.

An experimental study for bond slip behavior of concrete and a FRP plank was used as the both formwork and the tensile reinforcement for a concrete structural member is described. For the FRP plank and the concrete to act as a composite structural member a satisfactory bond at the interface between the smooth surface of the FRP and the concrete must be developed. This study focuses on investigation of the bond slip behavior of sand coated interface between FRP and cast-in-place concrete experimentally.

Externally prestressed structures have many advantages such as easy prestressing control and visible maintenance. Flexural strength of externally prestressed concrete members can be calculated by analysis of internal indeterminacy, which is different from internally prestressed concrete members. However, it needs nonlinear analysis considering member stiffness at strength limit state. Thus most of design codes proposed approximate methods which are empirical, based on test results. To reduce difference between accurate analysis and approximate design methods, many experiments and studies are continued. Since most of the experiments are single span beams. In order to adapt of continuous beam it needs further investigation for the continuous beam. In this study, we carried out externally prestressed 2-span concrete beam test to find out the flexural behavior and strength of externally prestressed concrete members.

In order to determine a minimum thickness of the pultruded GFRP panel as a structural member, some experimental studies were performed. GFRP tubes with 2mm, 4mm, 6mm thickness were manufactured by pultrusion process. First, coupon tests for finding mechanical properties were carried out. Comparisons between test results and analysis results based on classical laminate theory showed large differences in case of 2mm, 4mm specimens. The reason is that it is difficult to apply appropriate pultruding force and keep layered stitched fabric flat for the pultrusion process of complex shaped FRP member with small thickness. On the consequence, we decide 6mm as a minimum thickness of FRP member. Second, 4-point bending tests were performed and the results with compared with numerical analysis. The behavior of FRP tube can be exactly predicted by numerical analysis if buckling analysis is included.

An experimental study on the bond strength of wall-slab joint in SC(steel plate-concrete) structure was performed. Six-full scale specimens were tested. Specimens were constructed with key variables, such as, development length, location of the bar and quantity of the shear bar. The experimental results, show that as the development length and quantity of the shear bar increase, the bond strength increases. As the bars is located on the inside the stud bolt, the bond performance was highly increased compared to the bars located out of plane of the stud bolts.

Joint structures of composite truss bridges can have the same details for the connection between diagonal members and upper concrete slab as the connection between diagonal members and lower concrete slab. Adequate connection details should be decided according to design codes, constructibility, and economical evaluation. It is necessary to clarify the design check items and load transferring mechanism because combined external loads on composite truss bridges are concentrated at the joints. Joints with gusset plates and stud connectors are applied and complicated joint details may arise some problems in construction. This paper deals with experimental evaluation of the joints in composite truss bridges and proper design provisions were investigated to enhance the details. Push-out test specimens with group studs were fabricated and the effects of grouping and bent studs were studied.

To study the effect of the macroscopic TVLEM(Three Vertical Line Element Model) which is developed in 2D, a bearing wall system is selected and 2D and 3D pushover analyses are carried out. In 2D model, the participating width of a flage wall to lateral resistance is modelled based on Paulay's effective width. From the comparisons of roof displacements, 2D model which uses the effective width of flange wall has better prediction and less analysis time than 3D model which has intrinsically the full width of the flange that causes higher stiffness and strength and shorter deformation capacity than 2D model.

The response of a reinforced concrete element under cyclic shear is characterized by the hysteretic loops of the shear stress-strain curves. Recent tests have shown that the orientation of steel grids in RC shear elements has a strong effect on the "pinching effect" and ductility in the post-yield hysteretic loops. In this paper, four RC elements are considered to study the effect of the steel grid orientation on "pinching effect" and ductility. The presence and absence of the pinching mechanism in the post-yield shear hysteretic loops are studied using the Rotating Angle Softened Truss Model (RA-STM) theory.

The purpose of this study is to propose the stiffness reduction factor for flat plate slabs under lateral loads. Current design code (e.g., ACI 318-05) requires considering the effects of cracks for calculating slab stiffness under lateral loads. This study collected the test results of 20 interior slab-column connections, from which stiffness reduction in each test was estimated with respect to the ratio of applied moment to cracking moment ($M_a/M_{cr}$). Based on collected data, this study proposed equations for calculating stiffness reduction with respect to $M_a/M_{cr}$. To verify the proposed equations, this study conducted the experimental test of interior slab-column connections under quasi-static cyclic loading. From the test, load-deformation curve is compared to that obtained from effective beam width method with the proposed equation for the stiffness reduction. It is shown that the effective beam width method with the proposed equation for stiffness reduction predicts accurately the test results.

A study for the nonlinear analysis of segmentally erected curved PSC(prestressed concrete) cable-stayed bridge considering the effects due to large deflections is presented. Various case studies regarding the effects of the material nonlinearities and the geometric nonlinearities on the behavior of segmentally erected curved PSC cable-stayed bridge are conducted. The numerical results on the bridge which has relatively low stress profile through the bridge deck section like the example herein show that the geometric nonlinearities has more significant effects on the structural behavior than the material nonlinearities.

Along with recent improvement of recycling technique, the quality of the recycled concrete aggregate have become very competitive to the natural concrete aggregate. Therefore, a practical use of the recycled concrete aggregate may be possible for structural members. Majority studies about the recycled concrete aggregate was emphasized a limitation of fundamental study concerned with a strength characteristics and durability of the recycled aggregate concrete. Therefore, for the extension of application of recycled concrete aggregate, this investigation verifies the strength characteristics and structural performances of PHC piles used with coarce and fine recycled concrete aggregate.

According to current bridge design code cable supported bridges are designed generally against 1000-year-return-period earthquake. Considering its importance, however, it may be desirable to design against 2400-year-return-period earthquake. But the seismic behavior of cable supported bridges under higher seismicity is not investigated fully. In this study, several cable supported bridges were analyzed under higher seismicity and then the response forces in prime members were compared with those analyzed under current design earthquake.

In this paper, the prediction method of internal temperature for reinforced concrete columns under high temperature is presented. Finite element method is employed to facilitate thermal analysis for any position of column. And the effect of the heat of vaporization is applied. To demonstrate the validity of this numerical procedure, the prediction by the proposed algorithm is compared with the test results from this study. The proposed algorithm is in good agreement with experimental results.

Under sustained load, the stress variation occurs due to creep and shrinkage of concrete on the sections of steel-concrete composite girders. In standard specification for highway bridge, the method of stress estimation considering time effects is based on the concept of Yassumi method. In this study, comparing the analysis results using the AEMM and Yassumii method long-term behaviors, the rationality of specified requirements is checked.

It is specified in KCI code that long-tenn deflection shall be determined by multiplying the immediate deflection by KCI code multiplier, unless it is obtained by a more comprehensive analysis. Therefore, in this study, the estimation method of long-term deflection by KCI code multiplier is known resonable by comparing analysis results using KCI code multiplier and AEMM.

RBSN Method, Rigid-Body-Spring Network Method, is a structural analysis method that overcomes the problems faced in FEM analysis of concrete or crack forming structures. In RBSN, irregular lattices are used to model structural components consisting of bulk material, curvilinear reinforcements, and their interfaces. Because reinforcements and their interfaces in the bulk material are freely positioned, meshing is irrespective of the geometry of the representing bulk material. In this paper, RBSN method of 3D is applied in simulating the pull-out test of FRP (Fiber Reinforced Polymer) embedded in concrete. The comparison of analysis results to experimental results shows that RBSN method simulates the shear-slip behavior very precisely. From the analysis results, 3D RBSN method is proven to be an effective and accurate analysis method for concrete structural analysis. Also, the results show that RBSN method can be a potential analysis method for concrete structures that can replace the current FEM analysis.

Flat plate slab systems have been commonly used as a gravity force resisting systems, which should be constructed with lateral force resisting systems such as shear walls and moment resisting frame. ACI 318(2005) allows the Direct design method, the equivalent frame method (ACI-EFM) under gravity loads and the finite-element models, effective beam width models and equivalent frame models under lateral loads. ACI-EFM can be used for gravity loads as well as lateral loads analysis. But the method may not predict the behavior of flat plate slabs under lateral loads. Thus Previous study developed a Modified equivalent frame method(Modified-EFM) which could give more precise answer for flat plate slab under lateral loads. This study is to verified the accuracy of a Modified-EFM under combined lateral and gravity loads. The accuracy of this model is verified by comparing the results using the Modified-EFM with the results of finite element analysis. For this purpose, 7 story building is considered. The analysis results of other existing models are included. The analysis results show that Modified-EFM produces comparable drift and slab internal moments with those obtained from finite element analysis.

There are representative two performance evaluation methods for performance-based design(PBD) of reinforced concrete structures by the nonlinear static analysis, one method includes the capacity spectrum method(CSM) suggested in ATC-40(996) and the other is the displacement coefficient method(DCM) in FEMA-273(1997). The objective of this paper is to compare and verify two methods and suggest the displacement-based design for new performance evaluation of reinforced concrete structures.

The recently developed confinement-shear lattice model is reviewed. The procedure for generating aggregates in a given specimen and the constitutive model for on aggregate-cement strut are shown. It is suggested that the model can easily be extended for early age concretes and fiber reinforced concretes. The state-of-art of the extension and the general procedure of the extension are given in this paper.

In order to evaluate the seismic performance of a reinforced concrete building structure, four different analyses are carried out. Firstly, conventional pushover analysis with code-specified inverted triangular load pattern is conducted. Secondly, the pushover analysis with uniform load pattern is performed. Thirdly, adaptive pushover analyses with spectral amplification for both EC 8 artificial and Northridge earthquake are carried out. Lastly, incremental dynamic analyses under a number of scaled PGA for both EC 8 artificial and Northridge earthquake record are performed. Comparative studies demonstrate that the adaptive pushover analysis may be able to explain the response characteristics that conventional pushover analysis with fixed load distribution fails to capture.

The purpose of this study is to offer an appropriate method of the degree of the flexural moment redistribution for continuous reinforced concrete beams. Twenty-four two-span continuous beams were selected to determine the manner and degree of moment redistribution. The concept of ductility is linked to the moment redistribution capacity and, consequently, the safety of the structure. Knowledge of the plastic rotation capacity of plastic regions of the structure is important for a plastic analysis or a linear analysis with moment redistribution. A nonlinear finite element analysis program named RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology) was used to evaluate the ultimate strength and degree of moment redistribution. The nonlinear material model for the reinforced concrete is composed of models for characterizing the behavior of the concrete, in addition to a model for characterizing the reinforcing bars.

A In this paper, a new prestressed concrete girder system is presented which is designed using a detensionable and retensionable system. Experiments were carried out in order to comprehend the behavior of detensionable and retensionable prestressed concrete girder system. Tension control tests were performed for the detensionable and retensionable system followed by the static loading tests to check the applicability of the girder system. The test results were found in good agreement with the analytical results which clearly indicates the reliability of the concept of detensionable and retensionable prestress concrete girder with projected flange.

One of the important aspects of ductility is redistribution. To see the difference of redistribution between reinforced concrete members and prestressed concrete beams, two span continuous concrete beams are tested. From the test results, we can get important information on the redistribution ratio. After occurrence of crack at support section, the redistribution ratio increased and after yielding they fluctated very much. Compare with reinforced concrete, the redistribution ratio of prestressed concrete beam changed more abruptly after yielding. Both of the them show limited redistribution up to 70%.

Most of the civil structures in Korea and abroad have many kinds of damages when they are facing over-loaded traffics, long-term serviceability, and severe environmental conditions. Repair, rehabilitation, and retrofit are important for maintaining the serviceability of structures. In recent year, VES-LMC has been widely used as repair material for bridge deck repair and rehabilitation, because the VES-LMC has a various benefits such as traffic opening after 3 hours of curing, higher durability and bond strength. In case of any structure repaired or rehabilitated with VES-LMC, those were influenced capacity of bond between the base layer of slab and VES-LMC as well as physical properties of each other materials. The capacity of bond depended on purity of interface, micro cracks, curing of VES-LMC and so like. A kind of popular concrete repair technique, High pressure water jetting equipment is extremely efficient at removing damaged concrete. Removing damaged or poor quality concrete from sensitive structures such as bridge, tunnels, multi-story car parking decks and runways, using the high pressure water jetting could remove damaged or poor quality concrete remaining healthy and sound concrete. Accordingly, the purpose of this study is that it was to evaluate effect of hydrodemolition on the bond strength of VES-LMC overlay compared with effects of other method such as breaker, untreated. Also, it was evaluated the effect of surface moisture.

This study is the part of the investigation of the state of the art in ultra high flowing concrete (UHFC), applied in practical field construction, in order to develop the technology for improving workability. This paper includes a brief introduction of water content variance properties in UHFC before and after the pumping operation. Test showed that water content in all parameters decreased after the pumping. This is due to the increase of an absorption ratio of coarse aggregate by the pressure of the pumping operation. thus decreasing the water content. Therefore it should be considered to find out the possibility, which can improve the workability, suffering from over viscosity by the lower water content, in field construction.

In this study it compares a Japanese standards which is most similar contents with domestic standards related with the light weight aggregate concrete and derives the fundamental data from the results so that it will be able to refer at maintenance of standards or specifications in future. The case of domestic is the actual more insufficient condition which is described in the standards and the specifications than Japanese standards. For the production of he domestic light weight concrete the development of general standards and construction guides and control of water content ratio of the light weight aggregates become accomplished rightly in quality of construction site.

The goal of waterproofing materials and construction method used for underground structure can be attained only when construction is done perfectly free of laitance, moisture and foreign substances on concrete surface. However, construction engineers agree that it is difficult to perfectly carry out such work in practice and realization of perfect waterproofing for underground structures is impossible in reality. Therefore, this study is to examine and explore waterproofing materials and construction method completely meeting environmental impacts that underground structures receive and thereby suggest waterproofing technology applicable to underground structures, in order to prevent problems caused by leakage for underground structures.

This paper presents the analytical results on the heat of hydration and induced thermal cracking of the wall elements in LiNAC that is a radioactive shield concrete structure. This wall elements measuring 1.2 m in thickness and 32 m in length tend to exhibit thermal cracking due to heat of hydration and high constraint effects caused by slab element located in the lower part of structure. In this analysis, four different construction stages were considered to find out the most effective concrete casting method in terms of thermal stress. Among the construction methods adopted in this analysis, the method of installation of construction connection measuring 1.2 m at the both side of wall elements was very effective way to control the thermal stress, resulting in increase thermal cracking index of wall elements in LiNAC structure. Finally, the wall elements in LiNAC structure was cast successfully according to the proposed construction method.

For a better understanding of the fracture behavior of concrete structures, knowledge of the post-cracking behavior of concrete material is essential. The tension softening diagram can describe the post-cracking behavior of concrete in tension. In this paper, Four points bending tests with a notch have been carried out to investigate tensile properties of the steel fiber reinforced concrete(SFRC). Poly-linear approximation method combined with FEM analysis is applied to the steel fiber reinforced concrete to determine the tension softening diagrams and also to certify the validity of the method. The simulated load-CMOD curves using the determined softening diagrams though the poly-linear approximation method completely agree with the measured ones.

This study, in order for perceiving the mechanical attribute followed by the explosive spalling of high strength concrete material under high temperature and evaluating capacity of endurance of material, targets understanding capacity of endurance of material such as explosive spalling in high temperature, temperature by thickness of clothing, transformation extent, transformation speed and displacement, stocking the maximum load based on the Allowable Stress Design Method. As a result of experimenting the explosive spalling attribute of high strength concrete material, the one possibly causing serious damage is the 50 MPa concrete. In all aspects of 60 MPa concrete, explosive spalling happens. Especially, it is hazardous enough to reveal all the iron bar. All explosive spalling is intensively concentrated on the surface of concrete for the first $5{\sim}25$ minutes, which urges for the explosive spalling protection action. As a result of evaluating the structural safety by the transformation of high strength concrete, while beam assures the fire safety meeting regulation, 60 MPa shows the dramatic increase of transformation, which only counts 84% of safety. In a column, both the concrete exclusion and excessive explosive spalling are concentrated upper part of column, which brings about the dramatic transformation, so it only meets the 50% of safety regulation. Likewise, in 80, 100 MPa concrete which was never experimented considering the condition of domestic structural endurance stocking devices, the faster collapse is expected.

In order to estimate the reduction of laodbearing capacity, followed by the attributive change of heat while high strength concrete structure is revealed on fire it is necessary to evaluate, it is necessary to evaluate the property of material under high temperature such as thermal conductivity, specific heat, compressive strength, modulus of rigidity and diminution figure. Therefore, this study is for the purpose of presenting evaluation data for the analysis of thermal behavior about the high strength concrete material under high temperature, through the experiment by manufacturing concrete(40, 50, 60, 80, 100 MPa) commonly used in the construction field. As a result of the study, in the case of physical attribute, it demonstrates a greater fluctuation of change than the one of 30 MPa concrete. In case of specific heat, the high strength concrete, shown the serious diminution between $500{\sim}600^{\circ}C$, presents the thermal change area corresponding to the change of high strength concrete. In compressive strength, regardless of intensity of concrete, all of them show the first intensity loss between normal temperature and $100^{\circ}C$, the dramatic loss beyond $400^{\circ}C$. The concrete weighing above 50 MPa shows a twice lower dramatic intensity loss than the one weighing $30{\sim}40MPa$. The concrete ranging from $60{\sim}80MPa$, shows the biggest diminution of modulus of elasticity under $400^{\circ}C$, which implies the structural unstability of temperature.

In this study a board was made with good fireproof materials of which test was conducted according to the fireproof test for KS F 2257 construction members, and the temperature in coated steel which has a possibility to explode with concrete surface was measured. It is not appropriate to use normal mortar or mortar covering mixed with P.P. fiber to take a measure to prevent the explosive splalling of high-strength concrete. To finalize an Al-Si (aluminosilicates) board-requires over 30mm in thickness at the minimum for the required fire resistance performance and explosion prevention.

The trends of research for concrete in recent days are the high performance, high flow, ultra high strength and high durability. These are being researched with a construction company and a materials company. Anyone have to use the good quality sand, gravel, high quality chemical compound and silica fume for ultra high strength concrete as yet. This paper was researched with the domestic materials, not use the high price silica fume for the development 100MPa ultra high strength concrete with laboratory tests and mock-up test.

Generally, the strength of concrete depends on factors of materials, mix proportions, compaction, manufacturing methods and curing and so on. And recently, it has increased the using of crushed sand for concrete due to the exhaustion of good natural aggregate. This is an experimental study to compare and analyze the fluidity and compressive strength of ultra-high strength concrete according to the replacement ratio of crushed sand. For this purpose, the mix proportions of concrete according to the W/B ratio and replacement ratio of crushed sand was selected. And then air content, slump-flow, O-lot, compressive strength test were performed.

Extrusion molding concrete panel is cured two times, that is the steam curing at atmospheric pressure and a high-pressure steam curing(autoclaving). Steam curing at atmospheric pressure is done before autoclaving and to acquire the proper strength for treat in process. Though this curing is the important factor on the quality of product and the speed in manufacturing process, it was not evaluated properly so far. Because of ignorance about curing, some engineers even think that the dry curing is better than the steam curing. This study is to investigate the properties of specimen according to variation of curing conditions in the coring chamber such as laboratory scale, pilot plant, and commercial plant. As estimating, in case of steam curing at atmospheric pressure to make extrusion molding concrete panel, moisture curing is better than dry curing and the desirable maximum temperature in curing chamber is about $50^{\circ}C$.

Mix design of C80A which is applied to the vertical members of The Burj Dubai Tower, the tallest building of the world, was performed so as to meet the requirements of rheological property, mechanical properties & construction sequences based on material analysis in Dubai, UAE. Experimental investigations were carried out to evaluate & optimize the quantities of total binders, the proportions of Micro Silica, Dune Sand & PFA, changes of S/a and the comparison of chemical admixture, etc. Approximately $65,000m^3$ of C80A concrete has been poured to the vertical members since 16-Apr-2006. In the actual application, it was showed that C80A has proper early strength achievement, excellent mechanical properties and satisfactory flowability & workability. The results of extensive site testing can be summarized that the average compressive strength at 28days is 98.8MPa, the average elastic modulus at 28days is 47.8GPa, the flow of concrete after pumping at the height of 250m (L72) was over 500mm.

In this study, recently, more highly effective construction materials are needed for a reasonable cause and economical structure system is required as the construction structures become more multi storied, large-sized and diversified. Also, the experiment was not carried out to investigate and analyzed the strength properties and flowability of ultra-high strength accroding to the types of mineral admixtures. Therefore, this is an experimental study to compare and analyze the influence of cementitious materials type on the fluidity and the strength properties of ultra-high strength concrete. For this purpose, it has decided to do the mix proportions of concrete according to the type of cementitious materials (fly ash, blsat furnace slag, silica fume, slag cement) and W/B(23.5, 27.5, 31.5%) has selected. And then we conducted an experiment to find out basic properties of the ultra-high strength concrete such as slump-flow, O-lot and the age of specimens(3, 7, 28, 56days) for compressive strength.

In this study, the experiment was carried out to investigate and analyze the influence of fineness of blast furnace slag powder on the properties of high strength concrete. The main experimental variables were water/binder ratio 27.5, 31.5, 35.5(%) water content $165kg/m^3$ and mineral admixtures such as blast furnace slag powder. Even in a case where the ratio of blast furnace slag powder is 70%, using a fineness of 8000 grade afforded a higher strength development than using a plain concrete, which indicates the potential of high utilization in the future. Although it has been pointed out that the concrete using blast furnace slag powder has a problem of yielding relatively low rate of strength development in the early age, it is demonstrated that this can be resolved by using a powder with fineness greater than 6000 grade. It is considered necessary that powder fineness should be upgraded for the applications such as high performance concrete to be used in high strength required areas by considering hydration heat control and early strength requirements in the future.

Recently ultra high strength concrete is actively being developed and studied, and this trend is explained with the following effects. Technological effects expected from the application of ultra high strength concrete include the reduction of section, the decrease of structure mass and the improvement of workability. Belite cement has properities like low heat of hydration, excellent long term strength, and durablity without admixture. so, Belite cement is suitable for mass structure which is needed high strenghth, high fluidity and heat property. The objective of this study is to examine the suitability of mixture ratio through experiment of basic physical properties and provide materials for the field application of ultra high strength concrete.

Recently, as structures become bigger and higher, it is needed that high strength, high flow and high durability concrete. Demanding of High performance concrete that equality is maintained without material separation while flow, strength is increased by using low W/C rate and admixture, carbonation does not occur because of dense filling and has high durability is increasing rapidly. Because this high performance concrete is superior to general concrete in workability and durability, it is widely used in many construction and engineering works fields. However, it is reported that when it was exposed in fire, violent explosive spalling would be happened. Therefore, the purpose of this study evaluates explosive spalling properties of fire damaged high performance concrete according to the heating time.

This paper investigates the effect of curing conditions on the strength improvement of polymer-modified mortars using epoxy resin with various curing methods. The polymer-modified mortars using epoxy resin are prepared with various polymer-cement ratios, and subjected to standard, hot water, heat cure and autoclave cures. The epoxy-modified mortars are tested for flexural and compressive strengths at desired curing methods. From the test results, the flexural and compressive strengths of the epoxy-modified mortars are hardly improved by the autoclave and hot water cures compared to the ideal cure of $20^{\circ}C$. Among the four types of curing methods, the strengths of the heat cured epoxy-modified mortars is largely improved. Especially, it is obtained in the mortars sealed with PVDC film.

The use of admixture(PNS type & PC type) played a important role in the development of rapid hardening concrete. This paper presents an experimental study on the effect of a kinds of admixture on hydration characteristics, mini slump, apparent viscosity of fresh cement pastes and workability, compressive strength properties of hardened concrete for rapid hardening. Measurements have showed that their characteristics depends on the type of the admixture. As a result, the excellent quality was obtained, also being widely used for the construction field is expected.

In this study, evaluation of fire-resistant performance for polypropylene fiber-mixed mortar was performed to establish specification for stability of tunnel structure against fire afterward. In the fire-resistant performance test with mix proportion of polypropylene fiber, cracks were observed for mortar under 0.15% of fiber content, but micro-cracks were remarkably reduced for mortar more than 0.2% of fiber content. From the results, we are concluded that optimal mix proportion of polypropylene fiber is $0.20{\sim}0.25%$.

In this study, evaluation of fire-resistant performance for polypropylene fiber-mixed mortar was performed to establish specification for stability of tunnel structure against fire afterward. In the fire-resistant performance test with mix proportion of polypropylene fiber, cracks were observed for mortar under 0.15% of fiber content, but micro-cracks were remarkably reduced for mortar more than 0.2% of fiber content. From the results, we are concluded that optimal mix proportion of polypropylene fiber is $0.20{\sim}0.25%$.

This study investigates the engineering and fire endurance properties of ultra high strength concrete. The mixture proportions with water to binder ratios (W/B) of 0.15 and 0.25 consist of various adding ratios, such as 0, 0.05, 0.1, 0.15, 0.2, 0.25 and 0.3 percent respectively, of polypropylene (PP) fiber. As for the parameters of specimens, fluidity, compressive strength and unloading fire test were carried out. Test showed that an increase of fiber contents had the favorable properties in fire endurance performance; specimens in W/B 15% required 0.3vol% of PP fiber and specimens in W/B 25% needed only 0.1vol% to prevent spalling.

This research has evaluated flowability of ultra flowing self-compacting concrete, which is limitedly used for traditional building structures, in accordance with the first class regulations of Japan Society of Civil Engineering(JSCE) that can be applied to overcrowding-arrangement of bar, as a part of application methods that ultra flowing self-compacting concrete is applied to both precast and prestress bridge structures. The experimental results show that the flowability is acceptable in ternary blended among binary and ternary blended mixings, which satifies the first class regulation of JSCE. It is also concluded to use fly ash to increase viscosity of concrete in the case of segregation resistance because of low viscosity in the mixture of slag from blast furnace and limestone micropowder. Satisfying goals of every mixing after U-box self-compacting experiment, we conclude that ultra flowing self-compacting concrete is applicable to bridges and civil constructions of overcrowding arrangement of bar with evaluation of flowability of ultra flowing self-compacting concrete.

Needs for the new technologies and cutting-edge Ultra Flowing Self-Compacting Concrete are emerging as the concrete structures are becoming bigger and more specialized recently. In North America and Europe, SCC, which has high resistance against flow ability and segregation, is being used as concrete material in applications such as precast and prestressed bridges, where reinforcing bars are overcrowdedly placed. In Korea, SCC has been utilized limitedly in building structures but its utilization should be expanded to engineering structures such as bridges. In this study, for the application in precast and prestressed bridges with overlycrowded reinforcing bars, USCC was mixed with admixtures to give a binary system and a ternary system according to the 1st grade rules by JSCE (Japan Society of Civil Engineers). Compressive strength and splitting tensile strength of the resulting USCCs were tested. Elastic modulus were compared with the values suggested in CEB-FIP code and ACI 318-05.

Ultra high performance concrete(UHPC) has an excellent strength, toughness, and durability. It seems that it is very efficiently applicable for various structures such as bridge, building. When it is used to bridge girder, It is possible to reduce the amount of concrete and steel, to cut down costs for construction. This paper estimated whether it was applicable and how it was efficient. It was confirmed that the height of girder could be reduced by 40% or more in using UHPC. We can also think that the stirrups can be removed considering the ductile tensile behavior of UHPC and that its very high compressive strength make the anchor plate smaller from this study.

In this paper, study on applicability and quality control of the concrete using crushed sand. Recently, Trouble of sand supply is occurred according to exhaustion of natural sand resources. Now, application of crushed sand are proposed for solution of trouble of sand supply. Therefore, this study evaluated properties of concrete using crushed sand which mixing rate and changing FM.

Recycled aggregate mortar contains plenty of calcium hydroxide to improve the strength of blast furnace slag, although the surface mortar made of recycled aggregate deteriorates adhesion to cement paste and blast furnace slag has a low initial strength. Therefore, this study assumes that the combination with both recycled aggregate and blast furnace slag will produce a better performance. The results of the experiment show that dry mortar made of recycled aggregate provides with higher strength than wet mortar does at the 3-day and 7-day age, while lower at the 28-day age. It indicates that a large amount of cement mortar made of dry recycled aggregate has deteriorated adhesion strength. The mixes with 30% and 50% of blast furnace slag and 50% and 75% of recycled aggregate provide with much better strength at the 7-day age, although they usually have latent hydraulic property at the 28-day age. It indicates that calcium hydroxide($Ca(OH){_2}$) in recycled aggregate has affected ground granulated blast furnace slag.

This experimental study is to evaluate the effects of recycled coarse aggregate replacement level on the mechanical properties of concrete produced at Batcher plant. The main test parameter was replacement level of recycled coarse aggregate with the ratio of 0, 30, 60 and 100% to the natural coarse aggregate. From the test results, it was found that compressive strength, elastic modulus and splitting strength are decreased with the increased proportion of replacement level. Therefore, some design coefficients or recommendations for elastic modulus and splitting strength of concrete need to be reconsidered with minor reduction factor of '0.85'.

In this study, the quality properties of recycled coarse aggregate, manufactured by the barcrusher, were compared to that of aggregate, manufactured by conservative systems. Test showed that recycled coarse aggregate, manufactured by the bar-crusher, had higher density and shape index, and exhibited lower absorption and abrasion ratios, compared with a con-crusher and an impact-crusher. This is due to the peeling-off effect of mortar, attached on recycled aggregate and the improved round shape of that.

This study tested gravity separation with pseudo heavy liquid to produce structural recycled aggregates and recycled aggregates for road construction.

The production of recycling aggregate is used to process in the crushing that recycling aggregate isn't perfect the concrete aggregate in Korea. This study is examine to the properties of recycling aggregate used method of trituration. Test item is the fineness, density and percent of absorptance, solid volume percentage of aggregate. The result is that first, the method of trituration is excellent to increase the time of trituration and steel ball but decrease washing water. Second, method of trituration is improve to the properties of recycling aggregate but aggregate of production is irregularity. And method of trituration have to study of the many test items.

This study is about the production and properties of waste concrete powder that recycling aggregate is crushed to the waste concrete. We researched the generation and the disposal of recycled concrete powder. It is chemica] and physical features that is compared and analysis according to its production system and repeated crushing of time. Recycled concrete powder is more generated wet process than drying process. In addition, the more it is repeated crushing of time, the more recycled concrete powder is generated. Recycled concrete powder is discovered that wet process is larger of the specific area, lower density and particle size.

Recently, Korea government prepared Act on facilitation of construction waste recycling in December 2003 for effective recycling of rapidly increasing construction wastes, and has enforced the Act on Jan. 2005. This Act limits the definition of recycled aggregates to the aggregates which obtained quality certificate and for this purpose, government has operated quality standard and certificate system of recycling aggregate. The objective of this experimental study is to evaluate the mechanical properties of recycled coarse aggregate concrete according to curing method by ready-mixed concrete. Compressive strength ratio of recycled aggregate concrete under air-dry curing/wet curing was $74{\sim}91%$. KCI code for conventional concrete overestimated elastic modulus for recycled coarse aggregate concrete.

In this study, recently it has to be solved urgently the unbalance of demand and supply about the fine aggregate because the sea sand is restricted by exhaustion of river sand and intensification of environmental law. In this background, manufacturing technology which can produce recycled sand from construction and demolition waste concrete mass is developed. However, the existed washing method has the problem which not only impurities but also many other things make poor quality. Therefore, it tries to conform in time necessity, the objective of this study is to develop the Sand Flux system which can product the high-quality recycled sand from wast concrete and high value-added technology of the high-quality recycled sand as basic materials for mortar and concrete. At the same time it will be able to improve the quality of recycled sand products as an experiment of the physical nature and a quality present condition the products of recycled sand from construction waste.

A light-weight aggregate with a surface layer was fabricated using glass abrasive sludge and expanding agents. The glass abrasive sludges were mixed with expanding agents ($Fe_2O_3,\;graphite,\;CaCO_3$) and formed into precursors. These precursors were sintered in the range of $700-900^{\circ}C$ for 20min. The sintered light-weight aggregate had a surface layer with smaller pores and an inner region with larger pores. The surface layer and pores controlled the water absorption ratio and physical properties. As the expanding agent fraction and the sintering temperature increased, the porosity and pore size increased. The light-weight aggregate with $Fe_2O_3$ and graphite as the expanding agents had a low water absorption ratio while the porous material with $CaCO_3$ as the expanding agent had a higher water absorption ratio and more open pores.

Over the past few decades, a considerable number of studies on the durability of concrete have been carried out extensively. A lot of improvements have been achieved especially in modeling of ionic flows. However, the majority of these researches have not dealt with the chloride binding isotherm based on the mechanism, although chloride binding capacity can significantly impact on the total service life of concrete under marine environment. The purpose of this study is to develop the model of chloride binding isotherm based on the individual mechanism. It is well known that chlorides ions in concrete can be present; free chlorides dissolved in the pore solution, chemical bound chlorides reacted with the hydration compounds of cement, and physical bound attracted to the surface of C-S-H grains. First, sub-model for water soluble chloride content is suggested as a function of pore solution and degree of saturation. Second, chemical model is suggested separately to estimate the response of binding capacity due to C-S-H and Friedel's salt. Finally, physical bound chloride content is estimated to consider a surface area of C-S-H nano-grains and the distance limited by the Van der Waals force. The new model of chloride binding isotherm suggested in this study is based on their intrinsic binding mechanisms and hydration reaction of concrete. Accordingly, it is possible to characterize chloride binding isotherm at the arbitrary stage of hydration time and arbitrary location from the surface of concrete. Comparative study with experimental data of published literature is accomplished to validity this model.

This study was performed to proof expansion effect of the mortar bar due to Alkali-silica Reaction (ASR) by ASTM C 1260 test. Recently, the failure case of cement concrete pavement by ASR was reported in Korea. Cement concrete structures are caused crack by ASR. The service life of cracked cement concrete structures by ASR will be shorted. In this study, crushed the slate rock producted Chungcheongnamdo Boryeong was caused 0.3% expansion at 14 days due to ASR by ASTM C 1260 test. The particular spectrum showed that the ASR gel was analyzed contents included Si, Na, K, and Ca by EDX (electron dispersive X-ray spectrometer). It was verified that the crushed aggregate was caused expansion by ASR in Korea.

This study includes the experimental investigation on the fatigue-bond behavior with respect to the various rates of steel corrosion. Major criteria of test variables are the rates of steel corrosion by chloride ion and the ratio of the applied stress to the bond failure stress. According to the test results, the slip versus number of load cycles relation was found to be approximately linear in double logarithmic scale, not only without steel corrosion but also with steel corrosion. This research will be helpful for the realistic durability design and condition assessment of reinforced concrete structures.

Deicing salt has been generally used for prevention of a road freezing in winter, and the amount is increasing every year. However, deicing salt may induce the decrease of bond strength, surface scaling, and environmental pollution, etc. The purpose of this paper is to suggest the fundamental data on safety and durability for concrete structures through the estimation of characteristics of chloride penetration with deicer types. According to the test results, as age of concrete is increased, chloride penetration depth is also increased independent of deicer types. However, there is no remarkable difference between deicer types. And when the estimation of chloride diffusion is carried out by immersion test, diffusion coefficient is decreased with ages, and short-term estimation may overestimate the coefficient.

Chloride penetration is the main reason which causes the deterioration of concrete structures. Chloride penetration of concrete structures due to chemical-physical phenomena can be profitably analyzed by means of model-based simulations. The main purpose of this paper is to analyze chloride penetration considering self-desiccation, convection and admixture(GBFS: granulated blast-furnace slag) effects. Basic governing equations are modified properly to apply these effects to chloride penetration analysis. Temperature and relative humidity data of In-Cheon from Korea Meteorological Administration are used for analyzing chloride penetration.

Worldwide, Certification systems for standard of material and quality of product exist very variously. Korean industrial Standard (KS) is most representatively certification systems in Korea. But laboratory of korea uses often ASTM, RILEM and JIS and these standards do not get into unionization. so, Granted that experiment is same, result still can different. Therefore, this research measured chloride amount of hardened concrete using identical material and wished to improve accuracy of chloride estimation as that comparison evaluate to each examination.

This study is aimed for investigating the engineering properties of concrete containing fly ash, slag powder and limestone powder. The results of this study are as follows; As limestone powder is incresed, slump, air loss and strength is reduced, variation ratio of length is reduced, dynamic modulus of elasticity and neutralization depth is incresed.

This study evaluates the physical mchanical properties, durability of porous concrete for pavement according to content of polymer and steel fiber to elicit the presentation of data and the way to enhance its function for the practical field application of porous concrete as a material of pavement. The results of the test indicate that in every condition, the void ratio and the coefficient of water permeability of porous concrete for pavement satisfy both the domestic standards and proposition values. Among the properties of strength, the compressive strength satisfies the standards in the specification of Korea National Housing Corporation as for every factor of mixture but in the case of the flexural strength, more than 0.6Vol.% of steel fiber satisfied the Japan Concrete Institute proposition values. The case when 0.6Vol.% of steel fiber and 10Wt.% of polymer are used at the same time shows that the loss rate of mass by Cantabro test became 36.7% better and freeze-thaw resistance became 33% better.

TSA(thaumasite sulfate attack) is one of the important and prevailing phenomena to damage concrete structures by sulfate attack. In the present study, the thaumasite ($CaSiO_3{\cdot}CaSO_3{\cdot}CaSO_4{\cdot}15H_2O$) has been observed by the authors and other researchers in concrete samples in laboratory or field. Microstructural and mechanical observations clearly confirm that the thaumasite formation is greatly associated with sulfate attack indicating mass loss, expansion and spalling in the sample. This study summarizes the results of observation carried out by the authors and researchers on TSA which thaumasite formation has been identified.

To predict service life of concrete structures exposed to chloride attack, surface chloride concentration, diffusion coefficient of chloride ion, and chloride corrosion threshold value in concrete, are used as important factors. of these, as the diffusion coefficient of chloride ion for concrete is strongly influenced by concrete quality and environmental conditions of structures and may significantly change the service life of structures, it is considered as the most important factor for service life prediction. The qualitative factors affecting the penetration and diffusion of chloride ion into concrete are water-binder(W/B) ratio, age, cement type and constituents, chloride ion concentration of given environment, wet and dry conditions, etc. In this paper the influence of cement type on the diffusion characteristics of chloride ion in concrete was investigated through the chloride ion diffusion test. For this purpose, the diffusion characteristics in concrete with cement type such as ordinary portland cement(OPC), binary blended cement(BBC), and ternary blended cement(TBC) were estimated for the concrete with W/B ratios of 32% and 38%, respectively. It was observed from the test that the difussion characteristics of BBC containing OPC and ground granulated blast-furnace slag was found to be most excellent of the cement type used in this study.

This paper presents the experimental results of frost durability characteristics including freezing-thawing and de-icing salt scaling of the concrete used for gutter of the road. Mixtures were proportioned with the three level of water-binder ratio (W/B), 0.58, 0.53, and 0.48, and two binder compositions corresponding to Type I cement without any supplementary cementitious materials (OPC) and Type I cement with 30% blast-furnace slag replacement (Slag30). Also, two different solutions of calcium chloride and water that contains 0 and 8g of anhydrous calcium chloride in each 100 mL of solution, respectively, were used to evaluate their effect on the frost durability resistance. Test results showed that the Slag30 mixture exhibited higher durability factor and lower mass loss values than those made with OPC. Among the mixture tested in this work, the mixtures (OPC and Slag30) made with a relatively higher W/B of 0.58 exhibited large amount of the de-icing salt scaling regardless of calcium chloride concentration. Finally, the use of slag can be used effectively in terms of economy and frost durability of the concrete designated for gutter.

The durability of reinforced concrete structures is severely degraded by mainly corrosion due to seawater attack and chloride ion diffusion in concrete. The deterioration of durability causes high repair cost for maintenance of marine concrete structure. In this paper, high-durability materials for prevention of rebar corrosion are investigated to promote the durability in marine concrete structures. For these, the effect of the mineral materials addition(SF, FA and BFS), the modified steel(stainless and coating steel). and corrosion inhibitors are compared.

This paper presents experimental results for durability performance of GFRP composite exposed to the $80^{\circ}C$ alkali solution. A total of 280 specimens for 4 types of additive and 7 cases of immersion time were prepared and tested. Additives used in this study were PVA, kaolin clay, and alumina powder. Specimens were immerged up to 30 days and tested for tensile strength for each immersion time. The results indicate that it is important to fill the inner space of GFRP composite densely to avoid the decrease of tensile strength. In this study, PVA additive showed better performance than other additives.

The durability of concrete involves resistance to freeze-thaw action, corrosion, permeation, carbonation, chemical attack and so on. Generally, properties of concrete have been well understood under the separate action of these deterioration mechanisms. However, in practice, the degradation of concrete usually is the result of combined action of physical and chemical attack and can be accelerated by the combined action of several deterioration mechanisms. In the present study, to evaluate the combined deterioration by freeze-thaw action and seawater attack, ground granulated blast-furnace slag or silica fume concrete with water or seawater as mixing water was exposed to 300 cycles of freeze-thaw action. Tests were conducted to determined the relative dynamic modulus of elasticity and compressive strength. Furthermore, The MIP analysis were performed on the deteriorated part of concrete due to freeze-thaw action and seawater attack.

Recently, as it has greatly increased the demand on the serviceability of subway, cable tunnel, the stability of the tunnel structures has been attracting the concern of engineers and researchers. The purpose of this study is to idently the various characteristics of lining concrete in subway structures. The nondestructive technique such as the surface hardness method and the extend of carbonation by phenolphthalein indicator and chemical analysis due to XRD are considered. Also, the concrete core was cut in three pieces per tunnel for the exact evaluation of strength.

In this study, field survey of carbonation for RC column in city is carried out and carbonation behavior in sound, joint, and cracked concrete is also analyzed. Futhermore, probability of durability failure with time is calculated through considering probability variables such as concrete cover depth and carbonation depth which are obtained from field survey. The probability of durability failure in cracked concrete with considering crack width and time is also calculated and service life is predicted based on intended failure probability in domestic specification. Through this study, it is known that service life in a RC column is evaluated differently for local conditions and each service life is rapidly decreased with decrease in cover depth and increase in crack width.

Reinforcement corrosion is the most important durability problem of reinforced concrete structures. One of the important factors affecting the steel corrosion is carbonation. However, existing carbonation test takes several months to obtain the results. Therefore, in this study, new rapid carbonation test equipment for concrete was developed and its applicability was investigated. The testing period can be reduced by increasing $CO_2$ concentration up to 100% in the equipment. It is found from the test results that the carbonation depth of concrete specimens tested for 2 weeks was $3{\sim}5$ times greater than that of specimens tested by existing test method. In conclusion, it would be possible to get the reliable test results enough to evaluate the durability of concrete structures in a short-period.

This paper presents experimental results for durability performance of GFRP composite exposed to various environmental conditions. Specimens were conditioned for 7 environmental cases and immerged up to 150 days. A total of 720 specimens were prepared and tested for tensile strength for each immersion time. The results indicate that the tensile strength of the conditioned specimens was significantly reduced, regardless of the environmental factors considered, due to the degradation of GFRP.

Concrete structures in the seashore are greatly affected by salt attack primarily due to airborne chlorides like it can be seen through the corrosion of rebar. This study intends to investigate characteristics on the salinity of the airborne chlorides in terms of areas. Salinity measurement devices were installed at 27 areas along with seashore throughout the country. The area index for airborne chlorides were established according to the measurements. In Gochang and Taean area showed higher value of area index over 10. In addition, the Eastern coast showed higher index compared to the Western and Southern coast.

The purpose of the this study of to define the critical corrosion amount of the steel cause the cracking of concrete cover. The major variables of the critical corrosion amount are concrete strength and thick of the concrete cover. In this experiment, the constant of stress concentration is added by a new variable. As a result of the experiment, it is confirmed to less decrease in the critical corrosion amount following the constants of stress concentration increased. Besides, electric currents were measured through a generator of constant voltage. When connecting constant voltage with corrosion circuit, it was discovered that magnitude of the change come out similarly between displacement on the concrete cover and electric current according to time.

The EVA polymer is used as a modifier in the repair mortar, which contains various admixtures and mineral admixtures. It has been reported that the effect of polymer in cement mortar by the cement-polymer ratio only, but effect of admixtures over the polymer mortar was unknown. In this study, the fresh and mechanical properties of polymer cement mortar influenced by the range of silica fume ratio were investigated. It was found that with increasing the ratio of silica fume, mechanical properties(compressive strength, flexural strength, adhesive strength) of repair mortar is improved and drying shrinkage is increased.

In this study, the repair method using PVA fiber reinforced mortar evaluated on durability performance. Test of salt injury, carbonation, freezing-thawing, chemical attack, permeability was performed As for the test results, it was found that durability performance of the repair method using PVA fiber mortar showed more better than the existing repair method. Therefore, appling on the repair method using PVA fiber reinforced mortar, the repaired concrete structures can be increased to service life.

In this study, the beam which is repaired as high toughness cementitious composites evaluated on flexural performance. As for the test results, it was found that high toughness performance of beams of the repair as high toughness cementitious composites showed more better than the existing repair method and demonstrated about 95% semi-reinforcement to compare with reinforcement of carbon fiber sheets of one layer without interface and brittle failure. Therefore, appling on using PVA fiber reinforced high toughness cementitious composites, the repaired concrete structures can be increased to flexural performance.

The various rib geometry of hybrid fiber reinforced polymer (FRP) reinforcing bars were analyzed by finite element method. From the analysis result, two types of hybrid FRP reinforcing bars such as spiral and cross type with the same dimension of rib geometry were fabricated in this study. To evaluate the bond properties of them, direct pull-out test was performed. All testing procedures including specimens preparation, set-up of test equipments and measuring devices were made in accordance with the recommendations of CSA Standard S806-02. From the test results, it was found that cross type hybrid FRP reinforcing bars showed the highest bond strength than that of the others due to the higher relative rib area.

High-rise and large size buildings require high strength concrete and steel structure as a necessity. However, high strength concrete and steel structure are strong material but have a weakness to high temperature. Therefore, fire protection is a matter that must be considered very importantly in design for structure of high strength concrete and steel. Fire proof board that is existing method for fire proof has relatively low performance in fire protection emphasizes the need of new fire protection material due to the using of in numerable inflammables like plastics. The objective of this study is to understand the fire-resisting performance of newly developed fire protection material for building. This paper describes the results of fire tests using ISO curve that is fire protection regulation for buildings of the newly developed cementitious fire protection coating material applied concrete tunnel lining specimens.

Due to contaminated environment many concrete structures are carbonated. It causes the corrosion of rebar and induces the cracks of concrete, eventually. This study investigates the mechanism and properties of the alkali recovery agents(ARA) which are currently applied for repairing concrete structures on sites. The results indicate that the ARAs are not sufficiently effective to the realkalization of concrete structures.

Recently, fiber cementitious composite has been researched due to its good ductility. In this paper, Ductile Fiber Reinforcement Cementitious Coposite (DFRCC) is applied as reinforcement in concrete to prove its better performance. Compare to ordinary concrete, DFRCC has higher ductility which helps control the propagation of cracking without decreasing the elastic modulus and ultimate strength. In this research, experiments of different mixture ratios have been implemented to find a suitable mixture ratio value to produce high performance DFRCC material.

Normally, deterioration in the concrete structure is due to carbonation and chloride ion attack. Therefore, concrete structure is needed to surface protection for increase durability using impregnant. Impregnant classify into two large groups in polymeric and silicate materials. Silicate impregnant is included silicate and alkali silicate(sodium and lithium silicate). Thus, this study is concerned with self cleaning hydrophilic property of concrete structure using silicate impregnant. From the experimental test result, TEOS and lithium silicate make good use of hydrophilic impregnant.

The exist waterproofing membrane cause not to assure proper thickness in constructing. It become a serious problem which as decreasing of durability, waterproofing membrane to be tom and break down. Therefore, it is necessary that the expert have to construct waterproof works,, if not, it can be frost and thawing or chemical corrosion called one of the reason in maintaining the safety of concrete structure. In summarize, for this paper, it would be understand that exposed and compound experimental study of waterproofing sheet using coat material filling into the protuberance to improve the durability for concrete structure can widely apply to field to solve the these significant problem.

High performance fiber-reinforced cementitious composite(HPFRCC) encompass a wide variety of cementitious composites whose behavior in tension is significantly more ductile than that of traditional fiber-reinforced concrete. Fibers in HPFRCC are increasingly being used for the reinforcement of cementitious matrix to enhance the toughness and energy absorption capacity and to reduce the cracking sensitivity of the matrix. In the past decade, HPFRCC have evolved with intensified research. HPFRCC for structural applications has been developed under the performance driven design approach. It is the aim of this study to obtain development of HPFRCC using polyvinyl-alcohol fiber(PVA). It was targeted a requirement of economic mixing and apply to structure member.

HPFRCCs(High performance fiber reinforced cementitious composites) exhibit characteristics of strain harding and multiple crack. These lead to improvement in ductility, toughness, and deformation capacity under compressive and tensile stress. These properties of HPFRCCs are affected by type of fiber, size of sand. Furthermore these influence compress strength and flexural strength. Therefore experimental study on the mechanical properties of HPFRCCs using PVA fiber was carried out. In this paper, HPFRCCs made of PVA fiber were tested with size of sand, strength of concrete to evaluate characteristics of compressive strength and flexural strength.

Recently, various concrete reinforcing fibers have been used to reduce the plastic shrinkage cracking which occurs before the concrete hardens. In this study, the physical properties of nylon fiber reinforced concrete such as slump, air content, compressive strength and tensile strength were investigated. In addition, the performance of nylon fiber in the plastic shrinkage cracking reduction of concrete has been estimated in comparison with polypropylene, poly vinyl alcohol fiber and cellulose fiber. Nylon fiber showed considerable advantages in terms of the workability of concrete and the plastic shrinkage cracking reduction of concrete compared with polypropylene fiber and cellulose fiber.

Concrete secondary product that use cement is increasing application from reason of shortening etc.. of construction period in construction site. Manufacture method of construction of this concrete secondary product there is hot-check method, direct spray method, press method, extrusion molding method etc.. Also, I am using reinforcement boating certainly in this process. In most case, We have used asbestos by reinforcement fiber until early 90s but use from human body hurtfulness controversy is felt constraint. Therefore, application of principal parts fiber is increasing. But, to replace asbestos, because must satisfy all lubricating ability, productivity etc.. class, it is the very difficult matter to replace asbestos. In this study, I wished to do Test about asbestos principal parts possibility at extrusion process to charge shape or form making test piece because mixs polypropylene fiber etc. by plan that replace asbestos in cement extrusion molding product and measures bending strength and elasticity.

Recently, large efforts have been made to develop and understand the behavior of Fiber Reinforced Concrete. As in the static loading cases, many researches have been done. However, a few studies have been conducted in cyclic behaviors of FRC. The main objective of the present work is to investigate the cyclic behavior of fiber reinforced concrete with theoretical method. First, cyclic constitutive relations which describe the crack bridging stress considering non-uniform interfacial bond degradation in short randomly oriented fiber reinforced matrix composites under uniaxial cyclic tension were considered. A cyclic degradation model of single fiber based on micromechanics also taken into consideration. As an example, fatigue analysis for ECC with PVA fiber was conducted using proposed equations. Results shows that proposed method can establish a basis for analyzing cyclic behavior of fiber reinforced composites.

Steel FibreReinforced Shotcrete(SFRS) is one of the main tunnel support along with the rock bolt during the excavation and after the completion of the tunnel. In the standard qualification of the SFRS defined by Korea Highway Corporation, 28 day core specimen has to meet the compressive strength of 19.6 MPa and over 90 % fibre contents. Furthermore, for the 28 days brick shaped specimen made by shooting, flexural strength should be over 4.4 MPa and flexural toughness ratio which can be calculated from flexural toughness factor has to meet more than 68% of flexural strength. In shotcrete, accelerating agent is added for the rapid strength development. Silicate and aluminate type agents are known to develop shotcrete strength rapidly, however, has such problem to degrade the middle and long term strength. Hence, using poly carboxylic super plasticizer, it was aimed to enhance the quality of the shotcrete with the lower water-cement ratio and the same level of workability. The present paper shows the part of the field test result and its analysis.

Tensile as well as flexural strengths of concrete can be substantially increased by introducing closely spaced fibers that would obstruct the propagation of microcracks, therefore delaying the onset of tension cracks and increasing the tensile strength of the material. Fibers of various shapes and sizes produced from steel, plastic, glass and natural materials are being used. In this study, we used cellulose chip fiber to decrease the shrinkage crack in mortar and concrete. Specially, we have studied the dispersion characteristic of cellulose chip fiber. As a result, it was assumed that the slurry type of cellulose chip fiber is very effective to disperse the fiber in mortar and concrete.

Control of the temperature difference across a section is an effective way to minimize the hydration-heat-induced cracks for the structures where internal restraint is dominant. However, surface temperature may not be easily measured in situ due to the difficulty in maintaining the correct location during casting. A prediction equation for the temperature difference is proposed which can be applied without directly measuring the surface temperature if the curing condition and ambient temperature are known. Some strategies to control the temperature difference are revisited and a reasonable range of the temperature difference to minimize the crack is discussed.

As the concrete structure being large-sized and/or high-strengthened, the control of the hydration and curing temperature is made much account. This study, analysing the concrete temperature history from cylindric specimen and mock-up structures, investigates the effect of the early age curing condition and the optimum method of curing temperature control on mass concrete.

The crack of concrete induced by the heat of hydration is a serious problem, particularly in massive concrete structures. In order to control the temperature crack of massive concrete, the selection of appropriate materials like low heat cement, mixture materials, etc. is essential. In tills study, mix proportion using low heat portland cement and lime stone powder was designed and the best mix proportion, B-1, was selected. When bottom slab of the #219 LNG tank in Incheon was constructed, concrete temperature was measured. And thermal stress was analyzed about bottom slab of the LNG tank. As results of the thermal analysis, crack index was 1.60 in bottom slab and satisfied with construction specifications(over 1.0).

In massive hardening concrete structures, early age thermal cracking due to the heat of hydration may occur. There are many massive structures in Incheon bridge project and they have to be carefully treated to prevent thermal cracking. In this paper, an example of analyzed and measured results of hydration heat of pile caps in the Incheon bridge project was represented. Finite element simulations were carried out before casting and curing method was determined using the analyzed result. Sensors were installed before casting and temperature and strain of concrete was measured during curing. Gathered data were compared with the analyzed data and selected control method to prevent cracking was verified. Analyzed result gave good agreement and very few cracking could be found.

The unique technology was developed to control the hydration heat of mass concrete by adding the Phase Change Material(PCM) to concrete. The PCM was designed to liquefy at 60 degrees and its size was limited under $10{\sim}30$ micro meters to be put in pores and to have no effect on compressive strength. In the hydration heat test, center temperature of the PCM specimen was reduced by 10 degrees without any difference in the strength. Even in the adiabatic temperature rise test, the final adiabatic temperature rise amount was reduced as much as 25% in comparison with the standard value in Korean Concrete Standard Specification.

Recently, the attention is paid to the problem of thermal crack by hydration heat according to the increase of high strength and mass concrete structures. At this point, various research has been carried out for the control of hydration heat in high strength and mass concrete. As a part of the research, the application of Low Heat Technology (LHT) for the control of thermal crack by hydration heat was investigated in this study. To investigate the application, it was selected LHT which can reduce hydration heat of concrete with effect in series I and II. Also, it was investigated the characteristics of hydration heat generation of low heat concrete using LHT with binder types in seriesIII.

The bigger of concrete structures by a construct technique improvement, and the increase of the cement quantity which is caused by with use of the high-strength concrete for the load-carrying-capacity and a durability cause temperature cracks by a heat of hydration. The temperature crack due to the heat of hydration classified a nonstructural crack. but it has a bad effect on durability of concrete structures. especially, in case of a subway concrete box structure, when a water-proof facilities is beaked on an outer-wall, the water leakage occurs through a penetration crack generated from a wall of the concrete structure too. This paper, for the subway concrete box structure, which is located in chloride attack region, the use of blended cement, the temperature of air and concrete, was considered and analysed by a three dimensional finite element method.

It is necessary to develop a new technology for controling thermal cracking by hydration heat according to the increase construction of massive concrete structures, high strength concrete and early strength concrete. Therefore, it was investigated the characteristics of hydration heat generation of low heat concrete using hydration heat reducing admixtures in this study. To investigate the performance of hydration heat reducing admixtures, it was evaluated hydration heat according to the kind and replacement ratio of phase change material series I, II and the way of using hydration heat reducing admixtures in series III.

The main purpose of this research was to enhance the durability in both the design and construction of dams. Especially, in case of rockfill dams, the durability of tunnel concrete in a concrete-faced rockfill dam(CFRD) is achieved by optimizing the fly ash replacement for cement and application of steel fiber. The effect on durability and thermal property corresponding to the increasing replacement of fly ash and application of steel fiber was evaluated, and the optimum value of fly ash replacement and steel fiber application was recommended. The results show that 15% of fly ash replacement and $20kg/m^3$ of steel fiber application was found to be an optimum level and demonstrated excellent performance in durability and thermal property.

The Yang Pyeong bridge is high the occurred possibility of temperature crack by means of hydration Heat when the foundation of is constructed. Therefore, a pipe-cooling method was applied for reducing the temperature crack. Using the measured temperature curve when construction was carried out, the measured value and different facts were analyzed. In this paper, cause and analysis with respect to a mentioned above is to discuss firstly, and thermal characteristics of concrete and construction method hereafter is also discussed.

In this study, particle size distribution of cement powder system were adjusted using the blast furnace slag powder, Blaine $2250cm^2/g\;and\;8300cm^2/g$, which easy to adjust particle size distribution to examine how particle size distribution of the binder has an effect on rheological properties of the cement paste. In addition, the relationship between n-value of Rosin-Rammler function and plastic viscosity were discussed. All measured flow curves represented thixotropy behavior and the hysteresis area was smaller for the more added coarse particle. When the combination was based on a ratio of $20{\sim}25vol%$ fine particles, $30{\sim}40vol%$ OPC and $40{\sim}45vol%$ coarse particles of the total volume, a high fluidity and low yield strength was achieved.

This research investigates the characteristics of chloride fixation in non-sintering cement(NSC) matrix. NSC was manufactured by adding phosphogypsum and slack lime to granulated blast furnace slag as sulfate and alkali activators. As a result, the concentration of chloride ion in pore solution of NSC-solidified matrix is more low than that of OPC-solidified matrix containing the same chloride content in cement paste. Also, the concentration of chloride ion in pore solution of NSC-solidified matrix is similar with that of BSC-solidified matrix containing the same chloride content in cement paste.

Portland cement is presently the most widely used construction material. The process of manufacture of cement consists essentially of grinding the raw materials, mixing them intimately proportions and burning in a rotary kiln at a temperature of up to about $1450^{\circ}C$. Raw materials have used limestone, clay, silica, and iron oxide and fuel have used bituminous coal. Recently, A standpoint of the recycling of material resources, the production of cement use of industrial waste and residual products. Therefore, the final product of cement were included heavy metals such as $Cr^{+6}$ and Pb. The purpose of this study is standardization for $Cr^{+6}$ analysis in cement and concrete. From the comparative study of the examination method of $Cr^{+6}$ analysis, Japan cement association standard of $Cr^{+6}$ analysis is most suitable for the real state of affairs in korea.

In the many kind of construct-material, the concrete which has the high-strength and a durability is sufficient to use with structure-material. But the color of concrete is very monotony so generally concrete isn't used the out surface. although color concrete is a method of expressing surface, the combination of pigment and cement cause many Physical problem such as efflorescence phenomenon, strength degradation and so on. In this study, It attempt to develop the black mortar using the industrial by-product and to evaluate basic physical properties compare with general color concrete to solve the color concrete problem. The result of experiment showed that Black NSC which was made by-product has more visible black color than any mortar.

A cement which is used in construction and a concrete which is a hydration product of cement is considered anti-environmental materials because of lots of $CO_2$ emission in progress of producing and making them. But a concrete absorbs the $CO_2$ gas in atmosphere after hydration and in its lifetime. Based on Papadakis' theses, this research is carried on calculation of the $CO_2$ absorption quantity in concrete. Also, the emission of $CO_2$ was calculated by cement manufacture. As a result, It is said that the $CO_2$ which was emitted during cement manufacturing, was absorbed the 53% of emission quantity by the carbonation of concrete.

The study focuses on the mixture of materials for the development of porous concrete with unsaturated polyester resin. The materials used in the mixture include the coarse aggregates unsaturated polyester resin as binder, calcium carbonate and sand as a filler. An experimental procedure has been carried out to select the best combination of the materials that satisfy both the required permeability and compressive strength.

This study investigates the fundamental properties and examines spalling appearances and residual compressive strength of high strength concrete containing hybrid organic fibers subjected to fire. Test showed that overall, an increase of fiber content decreased the fluidity of concrete, but specimens containing polyvinyl alcoho(PVA)+polypropylene(PP) fiber and nylon(NY)+PP fiber had improved flow. In addition, the air content of all specimens was properly ranged in target value, regardless of fiber content. As for the spalling properties when completed the fire test, control concrete exhibited spalling occurrence due to sudden elevated temperature. However, specimens containing more than 0.1 vol% of PP fiber prevented the spalling, while specimens containing PP+CL and PVA+PP fiber can protected from fire in more than 0.15vol% of the fiber content. Importantly, a specimen containing only 0.05vol% of NY+PP showed the favorable spalling resistance performance.

Autoclaved lightweight concrete (ALC) have high water absorption, low compressive strength and popout the origin of the low surface strength in its properties. These properties make troubles under construction such as cracking and popout. Thus, this study is to improve the fundamental strength by control of $SO_3$ ratio's and Sand Sulrry grain size. From the test result, Improved ALC have a good fundamental properties. Compressive strength, and abrasion's ratio were improved depending on increasing $SO_3$ ratio's and Sand Sulrry grain size control.

This paper discussed pozzolanic reaction properties of classified fly ashes by using of electrostatic precipitator. Blaine values of fly ashes at hoppers are respectively about 3000(ordinary), 5000(fine) and 8000cm2/g(super-fine). The pozzolanic reactivity of fly ash at early stage and at later stage are respectively related to the related to the fineness and the glass content of fly ash. But the early hydration of cement was retarded by addition of super fine fly ashes. the adiabatic temperature rise of mortar containing fly ash is increased with the fineness of fly ashes.

This study aims to manufacture ultra fine cement(UFC) with a multi air-classifier of the dry-type. The classifier employed and devised for materials refining was a cyclone type fitted with an air suction device. This study also investigates the basic physical properties and quality of UFC and evaluates its utilizable possibility as a construction material. The basic properties of the UFC containing granulated blast furnace slag were analyzed and examined through recovery ratio, particle size distribution, scanning electron microscopy and compressive strength. Results obtained from the analysis of ultra fine cement have shown that there are possibilities for manufacturing UFC, which could compensate the weak properties of ordinary Portland cement.

Nowadays, It is openly reported that concrete structures have been attacted by freez and thaw. However, it is not clearly defined how to understand & measure the test method of freez and thaw of concrete structures. Thus, in this strudy, We performed the research with the test results using provision of ASTM C672 of freez and thaw durability of concrete. Also, it is identified suitable test method to measure of freez and thaw.

This paper investigates the properties of light weight foamed concrete with variances in adding ratio of stability agent(PS). Test showed that an increase of PS adding ratio decreased fluidity due to higher viscosity and increased unit weight of specimens. A sinking depth declined as the adding ratio of PS inclines, but all specimens including control concrete was ranging in KS; 0.5 to 10mm. Compressive strength value of specimens increased as PS adding ratio inclines. As for the tensile strength, any significant feature was not observed, compared with control concrete, but the ratios of camp. to tens. increased. Appearance density of concrete increased, and thermal conductivity was satisfied in KS, except for a specimen adding 0.07 percent of PS.

The effects of high temperature on strength, elastic modulus and strain at peak stress of concrete were experimentally investigated. The type of test was the stressed test that a preload was applied to the specimen prior to heating and the load was sustained during the heating period. In this study, the level of preload was 25% of compressive strength at room temperature. All tests were conducted at various temperatures(20,100, 200, 300, 400, 500, 600 and $700^{\circ}C$) for concretes made with W/B ratios 46% and 32%. Test results showed that on the whole, the relative values of strength and elastic modulus, and the real strain value at peak stress were not influenced by the W/B ratio.

This experimental study is the fundamental report to use the ternary concrete. This study performed to know physical properties of ternary concrete according to replacement ratio of pozzolanic admixtures and curing temperature conjugation. To investigate Strength development properties of according to replacement ratio of pozzolanic admixtures, both fly ash replaced on portland cement in 5, 10 and 15% weight ratios and blast furnace slag replaced on the portland cement in 5, 15, 20, 30 and 40% weigt ratios was used. Also this is studied fresh and hardened concrete properties in condition of curing temperature $10^{\circ}C\;and\;20^{\circ}C$. The followings are the summary of which concluded in this study. Considering the concrete cured over 28 days compressive strength, most replacement ratios of pozzolanic admixtures were higher than plain concrete that. Compressive strength development properties of ternary concrete according to curing temperature conjugation were similar except for early age.

Recently, owing to the development of industry and the improvement of building techniques, the concrete structure is becoming larger and higher. In hardening these large concrete, the heat of hydration gives rise to considerable thermal stress depending on the size and environmental condition of concrete, which might cause thermal cracking. Especially, the crack may cause severe damage to the safety and the durability of concrete structure. This study is investigated the thermal properties of concrete according to several binder conditions, such as OPC, Belite Rich Cement(BRC), Low-Heat-Mixed Cement(LHC), Fly ash added cement. As a result of this study, the Flowability of concrete was beetter with BRC and LHC than FA(25) and OPC. On the other hand, LHC gets superior effect in the control of heat hydration, it's caused by the volume of OPC.

This paper investigates the fundamental properties of light weight foamed concrete with the variances in unit weight of concrete and adding ratio of stability agent(SA). Test showed that concrete adding SA slightly decreased fluidity but secured stable flow appearances without segregation of concrete components. All specimens in a standard condition represented that a sinking depth was not observed, while, in the wet condition, a specimen adding SA decreased the sinking depth $2{\sim}4mm$ more than control concrete. Compressive strength values of control concrete showed $0.03{\sim}0.3MPa$ higher than the concrete adding SA. As for the tensile strength, the specimen adding SA also had lower value, while the ratios of comp. to tens. strength presented $0.43{\sim}0.62$, which is relatively higher than ordinary concrete.

This paper investigates the temperature history of slab mock-up specimens with various surface curing sheets, in order to determine a favorable surface curing method in hot weather condition. Test showed that insulating double bubble sheets+aluminum foil simultaneously on the upper section of a specimen prevented an increase of sudden temperature and a decrease of vaporization when placed during the hot weather condition. It also secured the high strength in early age. Therefore it is found that using the double bubble sheets+aluminum foil on concrete surface declined the plastic and drying shrinkage and inclined the early strength, thus improving the concrete quality.

The purpose of this study is to investigation the fundamental properties of alkali activated slag of type and concentration of alkali activator. In this paper sodium silicate, sodium carbonate and sodium hydroxide were used as alkaline activator and their concentration were 1, 3, 5 and 7 $Na_2O$ weight percent. The physical properties of alkali activated blast furnace slag cement mortar (AAS) were investigated by flow test and compressive strength. And the hydration properties of AAS characterized by X-ray diffraction and scanning electron microscope. Result show that Alkali activated slag mortar strengths were continuously increased with adding amount and ages. C-S-H were formed to be the main products up to 28days of hydration.

In this study, the rheological properties of fresh concrete of fresh mortar and concrete were investigated experimentally by shear box test. The pore water pressure in fresh mortar was measured as an influence factor of shear deformation of fresh mortar. As the result, it was clarified that the rheological properties is affected by the pore water pressure in fresh mortar and, the correcting method of shear stress in case of shear box test was obtained.

Normally, Structural light-weight aggregate concrete(LWC) has been main used in high rise building with the object of wight loss. In spite of LWC have the advantage of light-weight, limit the use of strength restrictions by reason that explosive spalling in fire. Especially, LWC is occurred serious fire performance deterioration by explosive spalling. Thus, this study is concerned with fire performance of LWC for the purpose of using PP fibers prevent to explosive spalling. From the experimental test result, LWC is happened explosive spalling.

Polycarboxylate type superplasticizers(PC) have got widely used for making not only high performance concrete but low grade concrete as well. It is known that fluidity of cement with PC is affected by the characteristics of cement especially sulphate ion concentration and hydration activity. But the characteristics of PC also affect the fluidity. The fluidity of cement mortar with various types of PC was measured and critical dosage(CD) and dispersing ability(DA) was calculated. CD and DA is strongly dependent on the type of PC. And the variation of fluidity on time was affected by the type of PC also. So, it is advisable to investigate the property of PC before production of concrete and adjust it to meet the requirements of concrete depending on the materials, the time of transport and so on.

At the present time, as part of the movement of natural resource conservation, there have been doing many recycling research works for wasted concrete, etc. In this study, we carried out an experiment for using crushed waste glass as a binder. It dealt with comparative analysis of the engineering properties of mortar containing crushed waste glass through a physical experiment. The experimental variables are the crushed waste glass powder substitution ratio(C-type : $0{\sim}25%$, B-type : $0{\sim}50%$, F-type : $0{\sim}100%$). According to this study, As the substitute of waste glass powder increases, air content and unit weight, the compressive strength decreases exactly proportion to the substitute ratio of waste glass powder. if, when waste glass is substituted as the binder, it is necessary to use an admixture.

This paper presents the results of tensile characteristics for developing FRP tendon with strand type. The performance targets were decided to compare the tensile characteristics of developing FRP tendon. Test specimens were manufactured by applying some improvements to enhance the tensile characteristics. The influence factors on the tensile characteristics have been found from the test results. Those are the fiber weight fraction, the pitch, the FRP cross sectional area, and the type of external fibers. The tensile characteristics were satisfactory compared to the performance targets.

Recently, improvements in the standard of living in industrial area require the establishment of a convenient residential environment in order to enhance the quality of living. To achieve such an environment, it is necessary to effectively reduce or prevent various environmental problems occurring in and around residential areas. Although conventional concrete has been regarded as a destroyer of nature, water and air can pass freely through concrete when it is made porous concrete by forming continuous void. In view of the harmony between nature and concrete, various research paths are being taken focusing on coarse aggregates to make porous concrete having continuous voids so as to improve water and air permeability, acoustic absorption, water purification, and applicability to vegetation. In this study, the Physical and Mechanical Properties of porous concrete according to compaction method analyzed by void ratio, coefficient of permeability and compressive strength.

This study investigated on the differentiation of microstructure of blast furnace slag concrete(BBSC) using Mercury Intrusion Porosimetry(MIP). From the test result, it was found that the BBSC did not show shortcomings of high temperature curing. The BBSC gives more fineness microstructure than that of plain concrete when it is cured same curing condition. The curing age making stable structure to poor surroundings was 28, 14, 7 days for blast furnace concrete cured at 5, 20, $30^{\circ}C$, respectively.

As this study is to estimate long term resistance of cement mortars using crushed sand under chemical attacks. Besides tests have been carried out with cement mortars by river sand and crushed sand by fine sand, cement mortars mix various proportions of silica fume and fly ash(up to 15% and 50% by weight for cement) were prepared and immersed in pure water, sodium sulfate solution, magnesium sulfate solution, seawater for 28days, 90days, 180days, 365days. Test on the change in the weight and compressive strength of cement mortars according to the duration of immersion time and the content of silica fume and fly ash was performed.

In this paper, experimental studies are performed to find out properties of crack according to the change of curing conditions of flyash concrete. To study the effect of curing conditions on flyash concrete, slump, bleeding, air content and hydration temperature of fresh concrete are measured according to various curing conditions. In addition, the effect of caring conditions on compressive strength, tensile strength and Plastic drying shrinkage cracking of hardened concrete is also considered.

The river environments of many streams in korea have been deteriorate through the rapid industrialization and urbanization since the 1960s. In korea, on the other hand, much efforts on the research and project have been made for the restoration of the deteriorated streams to close-to-nature. in order to restore the deteriorated streams, therefore, it is necessary to investigate such advanced technologies and materials. In view of this requirement, various research paths are being taken focusing on coarse aggregates to make multi-functional porous concrete having continuous voids so as to improve water and air permeability, acoustic absorption, water purification, and applicability to vegetation. The Purpose of this study is to investigate the method for recovery of the environment in the streams area using porous concrete painting block. the P.O.C block applies for test in the kyungan-cheon have been monitored planting during six month. after 6 months, plant grows flourishing and reconstructed in state such as nature rivers.

The purpose of study is to develope for lightweight concrete panel which have high quality with insulation performance of sound. The use of lightweight concrete products has been increased at a recently high structures. Also, the gathering of nature aggregate is limited, so that lack of fine aggregate is appearing. Statistical analysis is practiced on the properties of EPS concrete according to the variation of mix design. As a result saturated density is affected by amount of Bottom ash.Also compressive strength is affected by W/B ratio at the early age and amount of Bottom ash at the latter age.

This paper presents the experimental results on the development length of FRP tendons by direct pullout test. Two types of FRP tendons, namely, CFCC tendon and KICT tendon, and PS tendon were investigated. The development length defined as the minimum embedment length required to develop the ultimate tensile strength was suggested using the test results. It was found that the development length from the direct pullout test was greater than those of various standards. This may result from the fact that the wedge effect does not exist because there is no prestressing force in the direct pullout test. Further study and experiment are necessary to derive the reasonable development length for FRP tendon.

Recently, tunnels being constructed in korea with the increased construction of highways, high-speed railways and hydro structure. shotcrete and spray is one of the major processes in that construction. So general Shotcrete and spray has many problems on strength property, environmental pollution and human body noxiousness as the use of accelerater. However, In this paper using HES-LMS(High Early Strength Latex Modified Spray) without accelerater can solve problems which are mentioned above. problems that the hish early cement has can be solved by modifying material with latex. Therefore HES-LMS mortar is Classify by High performance and High ability. Analysis according to the variables such as W/C, Latex content and sand content is conducted. Studied about mechanical characteristic of material such as each parameter characteristic, and rebound characteristic is completed.

This study sought to investigate the characteristics of cellular concrete, such as porosity, strength and density, according to the cell addition rate. Based on the result, it examined the application to a cellular concrete panel. Porosity was found to increase according to the cell addition rate, measuring continuous porosity of 42% and 47%, and total porosity of 61% and 66%. In terms of cell addition rate, measurements were 7% and 11% respectively. Compressive strength represented 5.0MPa, 3.8MPa and 2.8 MPa in terms of 7%, 9% and 11% respectively, decreasing 1 MPa of strength according to every 2% increase of cell addition rate. Density showed 0.55, 0.44 and 0.36 in terms of 7%, 9% and 11% respectively, decreasing 1.0 MPa according to every 2% increase of cell addition rate proportionally. In addition the sandwich panel of cellular concrete which was fabricated during this research was found to be relatively heavy and non-flammable with an excellent strength of 4.0 MPa. Compared with a light concrete panel, considering the compressive strength that accountsfor 10 MPa, it appeared relatively low in strength. However it would be excellent for application due to the light density of only 0.4 MPa.

The lightweight foamed concrete is superior to properties of insulation and light-weight because it is included in many inner pore. So, lightweight foamed concrete used to construction field that need to property of insulation. The property of insulation of lightweight foamed concrete is varied with density. Also, Density is varied with hardening matrix and pore rate. The purpose of the experiment is to know thermal properties of specimen according to the change of density when heating the specimen. As a result of this experiment, the higher density, the lower temperature of mold. this tendency isn't same as ordinary lightweight foamed concrete, and then density 0.9 is expressed most low temperature result also the discontinuity of shape of mold was efficient for the prevention of the temperature rise.

It is known that cement production not only consumes large amount of energy but also contributes substantially to the green house gas emission. Therefore, there is a demand to develope a new technology to produce energy efficient and environmental conscious cements. The most recent, wood wool ceramic board is being applied in various building material field, for example thermal insulating and acoustic absorption material. This paper focused on improvement of the physical properties for wood wool ceramic board applied inorganic polymer binder. As the result of this experiment, what we could obtain better wood wool ceramic board's properties such as density, water contests, water resistance and band strength, was 0.46, $10{\sim}12%$, 1.9% and $40kgf/cm^2$. This result can be applicable to commercial wood wool ceramic board.

In the present study, the method and procedure for analysis of impact damage behavior for concrete under penetration and perforation of projectile is investigated. Conservation law, equation of motion, initial and boundary conditions, and FEM formulation are introduced and derived respectively. Specially, the constitutive equation which rate-dependent damage combined with rate-dependent plasticity within the appropriate framework of theory of thermodynamics is examined. This paper aimed at the review with respect to impact damage models for concrete to develop that model. This paper is a basis research for the development of impact damage model for concrete.

This study investigates the properties of light weight foamed concrete with variances in incorporating ratio of cement kiln dust(CKD). Test showed that an increase of CKD incorporating ratio decreased the fluidity of fresh concrete and increased the unit weight. A sinking depth of specimens incorporating CKD decreased, compared with that of control. As for the compressive strength, it firstly increased and then slightly decreased when incorporated CKD. Tensile strength values were similar to the values of compressive strength, but the ratio of comp. to tens. strength increased. Appearances density of specimens were all raged in KS and the thermal conductivity was also satisfied in KS; less than 0.05-0.160W/($m{\cdot}k$).

An experimental investigation was carried out to evaluate the transient strain of concrete at high temperature. Two level of W/B ratio were selected as 46% and 32%. Four level of preload were adopted as 0, 15, 30, 45% of compressive strength. The entire temperature range was between room temperature and $700^{\circ}C$. Based on the test results, transient strain of concrete at high temperature was affected by the compressive strength as well as the preload level.

By this time, various shapes and materials are used in Artificial Reef. A function of Artificial Reef is leading of fishes by adhesion of seaweeds, however, this effect was not enough. In this study, porous concrete containing function materials (protein, carbohydrates, and fat etc.) are investigated to maximize leading effect of fishes. For these, the mechanical characteristics of porous concrete are investigated with void contents and function materials. Also, the diffusion of function materials are compared to suggest the suitable content of functional material.

At the green roof on the concrete structure, root penetration can be the most problem to water leakage. Root occur cracks due to penetrate to concrete which have porous organization by itself. Crack on the concrete structure would be constantly shrinks and expands, it occur to water leakage and decrease durability of concrete structure. Therefore, in this paper, the result of the root penetration test for waterproofing which protect concrete structure from the water leakage or other environment conditions would be apply to understand the reason of root penetration.

The stochastic nature of the tensile strength of concrete is investigated theoretically and experimentally. The tensile strength of concrete was modeled by a theory based on the failure probability of a crack arbitrarily oriented within a concrete body. According to this model, the stochastic nature of the tensile strength depend on the current stress state. This aspect was checked experimentally using a classical three point bend specimen and a rectangular plate specimen loaded at the center. It has been known that the biaxial strength is no different from the uniaxial strength. However, if the region where the tensile strength is constant gets small, the biaxial tensile strength increases and its stochastical variation decreases.

Wasted phosphogypsum is a by-product from the phosphoric acid process of manufacturing fertilizers. It consists mainly of $CaSO_4{\cdot}2H_2O$ and contains some impurities. The purpose of this study is to utilize wasted phosphogypsum into an admixture for concrete products cured by steam This paper is to investigate the strength properties of cement composites containing high volume phosphogypsum. The cement composites were composed of OPC, phosphogypsum, fly-ash and granulated blast-furnace slag with activators. As a result, the strength of cement composites containing high volume wasted phosphogypsum were shown high level when granulated blast-furnace slag was mixed. Therefore, PG could be used as a steam curing admixture for concrete 2th production with reduction of OPC.

Nowaday, High strength concrete(HSC) has been mainly used in high rise building. HSC have superior property as well as improvement in durability compared with ordinary strength concrete. In spite of durability of HSC, explosive spalling in concrete front surface near the source of fire occurs serious problem in structural safety. Thus, this study is concerned with experimentally investigation fire resistance of the inorganic fire protection materials at high temperatures up to $800^{\circ}C$. From the test result, developed inorganic binder becomes general that with rising temperature the compressive strength of the material increases in tendency. Therefore, the results indicate that it is possible to fireproof panels, fire protection of materials, etc.

In this study, we compared and analysed the early strength properties of mortar according to the kinds and replacement ratio of mineral admixture to select the kinds and replacement ratio of mineral admixture of high early strength concrete. For this purpose, mortar mixtures according to the kinds(FA, MK, ZR, BFS, DM) and replacement ratio(0, 2, 4% by volume of sand) of mineral admixture were selected. From our test data, early-age compressive strength decreased in accordance with the increase of replacement ratio of fly-ash(FA) & blast furnace slag powder(BSF) and, in case of addintion admixture, early-age compressive strength of with containing ZR & BFS appeared higher compared with containing other mineral admixture.

This study examined plant adhesion characteristics of the porous concrete that used specially treated granular fertilizer for field application, which was used for the restoration of the marine ecosystem. The results of the experiment showed that nutrient eruption amount, the destruction and dissolution ratio tended to decrease when the coating thickness was increased. The void ratio and compressive strength tended to decrease when the specially treated granular fertilizer mixing ratio was increased. According to these results, the appropriate thickness of coating for cement coated granular fertilizer was 1.0mm. The adhesion ability of marine plant to porous concrete was superior when the cement coated granular fertilizer was mixed. Therefore, the appropriate cement coated granular fertilizer mixing ratio of 20% with a coating thickness of 1.0mm is thought to be a factor when considering the strength of the porous concrete for marine ecosystem restoration and the adhesion characteristics of marine plant.

This study concerned the quantification of environmental aggressiveness of concrete structure building up and applied to design of concrete structure. Only the content of carbon dioxide evacuated in the process of fabricating concrete structure was taken as an environmental load and various parameters, for example, material production, transportation, building-up, destruction and reuse were considered. Also, the life span of a concrete structure was taken into account in evaluating the carbon dioxide evolution. Consequently a single equation for the environmental load was obtained, which were subsequently used to assess the effect of high strength/durable concrete structures.

The government makes efforts to expand the recycling activities of construction waste soil and to increase the usage of recycled aggregate. Accordingly, it has defined the compulsory usage and quality standard by usage of recycled aggregate. To satisfy these efforts requires both technology to produce recycled aggregate which meets the required quality and companies with the technology. Therefore, it requires to review a current status of facilities at the companies which deal with construction wastes. The companies dealing with construction wastes gradually produce the high quality of recycled aggregate. In particular, companies which has over 3-stage processing system for waste concrete continue to increase and means to remove foreign substances are gradually improved.

In this study examines physical and mechanical properties the use of domestic low grade meta-kaolin in light weight porous concrete. For this purpose light weight porous concrete incorporating low grade meta-kaolin admixture, was tested for tensile strength and acoustic characteristics. Checking tensile strength of cement and low grade meta-kaolin mixture was used to determine the optimum mix proportion of the low grade meta-kaolin admixture. In this paper sound absorbing material has been investigated by using the light weight porous concrete.

This paper examined the applicability of convex hull, which is defined as the minimal convex polygon including all points, to assessment model for effective region. In order to validate the applicability of the convex hull to assessment model for effective region, a genetic algorithm was adopted as a optimum technique, and an artificial neural network was adopted as a prediction model for material properties. The mix-proportion obtained from the proposed technique is more reasonable than that obtained from previous work.

In this study, we conducted machinery analysis, such as differential thermal analysis, X-ray diffraction analysis and scanning electron microscope analysis, in order to predict fire temperature and to analyze fire damage in the case of fire on concrete structure. according to the machinery analysis and differential thermal analysis, concrete bought big creak over $300^{\circ}C$. these result can be utilized as good data in design for repair and reinforcement through rationally evaluating fire damage on concrete structure exposed to high heat or fire in the future.

This paper reports a comparative study for performance evaluation guidelines for bridge bearings. Guidelines for bridge bearings such as KS, EN1337, AASHTO LRFD, and Japanese code were analyzed. In addition, fatigue tests of elastomeric bearing are being conducted for allowable shear deformation and compressive stress. Based on literature survey and tests, the innovative concept of performance evaluation guidelines for bridge bearings is suggested.

현재 국내에서는 기존에 사용되었던 안정성 위주인 사양중심의 설계(prescriptive code)에서 구조물의 성능을 고려하여, 인명피해 뿐 아니라 구조물의 기능도 설계의 감안요소로 하는 성능 기반 설계기준(Performance-based design)이 도입되고 있는 추세이다. 본 연구에서는 일본 토목학회(JSCE), 캘리포니아 도로연방국(Caltrans), 유럽코드(Eurocode 8), 뉴질랜드 교량설계(NZ code)에서 어떤 식으로 성능기반 설계기준을 제시하고 있으며, 각 국가 간의 성능(performance)과 레벨(performance level)에 대한 접근 방식을 비교하고 국내의 성능기반 설계 도입의 필요성에 대해 논하는데 그 목적이 있다.

The effects of polymer-binder ratio, antifoamer content and shrinkage-reducing agent content on the air content and strengths of high-fluidity polymer-modified pastes are examined. As a result, the air content of the polymer-modified pastes tends to decrease with increasing polymer-binder ratio and antifoamer content. Irrespective of the antifoamer content, the flexural and tensile strengths of the high-fluidity polymer-modified pastes tends to increase with increasing polymer-binder ratio, and tend to decrease with increasing shrinkage-reducing agent content. However, the compressive strength of the polymer-modified pastes decreases with increasing polymer-binder ratio and shrinkage-reducing agent content.

The effects of polymer-binder ratio, antifoamer content and shrinkage-reducing agent content on the setting time and drying shrinkage of high-fluidity polymer-modified pastes are examined. As a result, the setting time of the high-fluidity polymer-modified pastes tends to delayed with increasing polymer-binder ratio. Irrespective of the antifoamer content, the drying shrinkage of the high-fluidity polymer-modified pastes tend to decrease with increasing polymer-cement ratio and shrinkage-reducing agent content.

Many non-destructive inspection methods have recently been developed for concrete structures. However, these methods can obtain only physical information of concrete, such as crack depth, delamination or position of reinforcement etc. near its surface. If chemical information is required, sampling and componential analyses may be earned out. Non-destructive method that can detect deterioration factors such as carbonation, chloride content or sulfate attack would be an outstanding innovation in inspection methodologies. In this research, near-infrared spectroscopy and X-ray fluorescence analysis were applied for componential analysis for concrete. These methods are very effective compared to traditional methods, therefore, working efficiency and maintenance cost will be improved.

According to the analysis of tension failure mechanism of UHSC specimen, one modified model based on ACK model by the introduction of partial debonding energy of non-first cracks and by the application of steel fiber number on unit area is presented in this paper. It can be used to explain the evolution mechanism of multiple cracking and pseudo strain hardening of UHSC. From the numerical results, to increase steel fiber length and to reduce steel fiber diameter in some region all can reduce the fiber volume fraction with the same multiple cracks for economic design of UHSC.

Construction industry is one of the fastest growing sectors in the world. Rapid construction activity and growing demand of houses have led traditional building materials. In order to satisfy that purpose, the researchers need to vary new and innovative building materials. This paper describes the experiment carried out to investigate the elastic coefficient of loess due to compressive strength.

Chloride penetration into concrete is a hot issue of concern all over the world, notwithstanding, very few attempts have been conducted to explore the effect of cracks on choride penetration. Cracks provoke to lose a main function of watertightness of concrete and lead to reduce the service life of concrete. For this reason, it is necessary to define a critical crack width to prevent a quick chloride penetration through crack. In this study, experiment is focused on establishing a critical crack width in terms of chloride penetration. Concrete specimens with different crack widths I crack lengths have been subjected to rapid chloride migration testing. In a side of analytical solution, a simple approach to quantify the chloride diffusion coefficient of only crack zone excluding sound concrete was proposed. The result clearly showed a critical crack width of 0.03 mm. Based on the experimental results, a phenomenological model was proposed to explain the meaning of critical crack width in practical engineering. In this model, cracked concrete zone was divided into three zones. These zones corresponded to a wide crack, a zone with micro-cracks and an uncracked zone.

An understanding of rheological property on cement paste is one of the important factor to design concrete such as High-fluidity Concrete (HFC) for a specific application. The HFC is a specially proportioned hydraulic cement concrete that enables the fresh concrete to flow easily into the forms and around the reinforcement and prestressing steel without vibration and segregation. Use of this type of concrete for the concrete building construction, manufacture of precast, prestressed bridge elements provides the benefits of increased rate of production and safety, reduced labor needs, and lower noise levels. This paper presents the performance of rheological properties of cement paste incorporating domestic high-water-reduced-admixture (HWRA) for an Ultra-high-fluidity concrete (UHFC). Investigation was carried out on cement pastes with combinations of various dosages of HWRA and water/cement ratios.

Sulfate resistance of mortar specimens with or without alkali-free accelerator exposed to sulfate solutions for 360 days was investigated. Test results confirms a negative effect of alkali-free accelerator on the sulfate deterioration, irrespective of attacking sources. Based on the ASTM C1012 expansion test, the experimental findings demonstrated that higher $C_3A$ content in cement led to the higher expansion, especially in the mortar specimens with alkali-free accelerator.

In order to predict the accumulated damages by cyclic freeze-thaw, a regression analysis by the Response Surface Method (RSM) is used. RSM has merits when the other probabilistic simulation techniques can not guarantee the convergence of probability of occurrence or when the others can not differentiate the derivative terms of limit state functions, which are composed of random design variables in the model of complex system or the system having higher reliability. For composing limit state function, the important parameters for cyclic freeze-thaw-deterioration of concrete structures, such as water to cement ratio, entrained air pores, and the number of cycles of freezing and thawing, are used as input parameters of RSM. The predicted results of relative dynamic modulus and residual strains after 300 cycles of freeze-thaw for specimens show very good agreements with the experimental results. The RSM result can be used to predict the probability of occurrence for designer specified critical values. Therefore, it is possible to evaluate the life cycle management of concrete structures considering the accumulated damages by the cyclic freeze-thaw by the use of proposed prediction method.