RC column bent piers represent one of the most popular piers used in highway bridges. Seismic performance of reinforced concrete (RC) column-bent piers under bidirectional seismic loadings was experimentally investigated. Six column bent piers were constructed with two circular supporting columns. Test parameters are different transverse reinforcement and loading pattern. Three specimens were loaded with bidirectional lateral forces which were main cyclic loads in the longitudinal direction and subcyclic loads in the transverse direction. Other three specimens were loaded in the opposite way. Test results indicated that lateral strength and ductility of the latter specimens were bigger than those of the former specimens. Plastic hinge was formed with the spall of cover concrete and the fracture of the longitudinal reinforcing steels in the bottom part of two supporting columns for the former three specimens. Similar behavior was observed in the top and bottom parts of two supporting columns for the latter three specimens.

In order to investigate the effect of the height of application point of lateral loads and reinforcing steel bars in walls and columns in improving the seismic behavior of confined concrete block masonry walls, an experimental research program is conducted. A total of four one-half scale specimens are tested under repeated lateral loads. Specimens are tested to failure with increasing maximum lateral drifts while a vertical axial load was applied and maintained constant. The constant vertical axial stresses applied are 0, 0.84 and 1.80MPa, while the amount of reinforcements in horizontal and vertical directions are $0\%,\;0.08\%\;and\;0.18\%$ respectively. Test results obtained for each specimen include cracking patterns, load-deflection data, and strains in reinforcement and walls in critical locations. Analysis of test data showed that above parameters generate a considerable effect on the seismic performance of confined concrete block masonry walls.

Coupling beams subject to cyclic loads exhibit different behavioral characteristics and energy dissipation capacity varying with re-bar layouts. In the present study, nonlinear analysis method was developed using analogous truss model. Using the numerical method, parametric studies were performed to investigate the behavioral characteristics and the energy dissipation mechanism of coupling beams with various re-bar layouts subject to cyclic loading. Based on the investigation, a simple and practical method for evaluating the energy dissipation capacity of coupling beams was developed and verified by experiments. The proposed method accurately predicted the dissipated energy during cyclic loading addressing design parameters such as re-bar layouts, re-bar ratio, and deformation. The proposed method can be easily applied to nonlinear static and dynamic methods for seismic analysis and design.

The PCS system, which consists of precast concrete column and steel beam, has been developed. The system is expected to achieve the effectiveness in the constructability and improve the structural performance under earthquake. New types of joint system for the panel zon and column connection has been developed in order to improve the shear strength capacity and rigidity of the of the system. The cyclic seismic test recommended by ACI was conducted to verify the structural performance of the system. As a test results, it is observed that the system satisfy most of the requirements by ACI criteria.

FRP strengthening system that bonds FRP sheet or laminate underneath structure has been used popularly thesedays. The failure of this bonding system occurs mainly at the interface of bonded surface abruptly. So it is difficult to expect the failure and FRP can't show its full material capacity that makes it uneconomically. By that reason, KICT proposed a system to install FRP aminate to structure for strengthening not by bondging but by unbonding. It is to install both ends of FRP laminate by anchoring underneath structure without bonding. Then, the failure is not an interfacial problem any more, it is governed by mechanical anchoring. This paper includes an experimental study about anchoring system for prestressing CFRP laminate.

Structural performance of the seismic devices made by steel bar and high performance fiber reinforced cement composites(HPFRCCs) was experimentally observed. These dampers will be applied for reducing damage as well as seismic response. The advantages of the HPFRCCs damper is selective structural performance, strength, stiffness, and ductility by changing configuration, bar arrangements and type of materials used. The experimental results indicate that elemental ductility is much increased with decreasing damage when the HPFRCCs are applied to the damper. It means cementitious damper for structural control is available which has much merit in performance and cost.

Many highway bridges in Korea need seismic retrofit because only one decade has passed since the seismic design criteria was introduced. In this experimental study, the effectiveness of base isolation bearings was discussed for the seismic retrofit of the highway bridges. Four real scale RC pier specimens were constructed for the test. These RC piers didn't have seismic details. Except for one RC pier for the pilot test, three types of bearings such as Pot bearing, Rubber bearing (RB), Lead-rubber bearing (LRB) were applied to the other RC piers respectively. The RC pier with Pot bearing means current state of the prototype bridge that is not retrofitted seismically. And two RC piers with RB or LRB mean assumed states of the prototype bridge that are retrofitted seismically. To simulate dynamic behavior of these RC piers under earthquake loads, Pseudo-dynamic test method was used.

An experimental investigation of the behavior of steel cords(SC) and SC and Polyethylene(PE) hybrid fiber reinforced cementitious material under compressive and tensile loading is presented. In this experimental research, the tensile and compressive strength and strain capacity of high performance fiber-reinforced cementitious composites(HPFRCC) were selected using the cylindrical specimens. Uniaxial compressive and tensile tests have also been carried out at varying strain rates to better understand the behavior of. HPFRCC and propose the standard loading rate for compressive and tensile tests of new HPFRCC materials. The results show that there is a substantial increase in the ultimate compressive and tensile strength with increasing strain rate.

The current Korea bridge design specifications have no provisions about concrete Barrier. And there are no test results of registence strength of the concrete barrier at the vehicle collision sites. This paper reports experimental results of concrete barrier on bridge deck conctructed by standard drawing of SB5 grade. Eight specimens were tested under static test. The specimens are divided by two groups (D-series and B-series). D-series is to show failure pattern of bridge deck. B-series is to show failure pattern of concrete Barrier. The test results compared with calculation results using Yield-Line theory of AASHTO LRFD Bridge Design Specifications.

An experimental study was conducted to investigate the stress-strain behavior of confined concrete columns according to transverse reinforcement volumetric ratio. Uniaxial loading tests of eleven column specimens$(250\times100\times500mm)$ with rectangular section were conducted to study effect of confinement. The main variables in this test are transverse reinforcement volumetric ratio and cross tie arrangement. the results indicate that the strength and the ductility of confined concrete columns are subjected to transverse reinforcement volumetric ration and cross tie arrangement.

This experimental investigation was conducted to examine the behaviour of eight one-third scale columns made of high-strength concrete (HSC). The columns were subjected to a constant axial load corresponding to 30 per cent of the column axial load capacity and a cyclic horizontal load-inducing reversed bending moment. The variables studied in this research are the volumetric ratio of transverse reinforcement, tie configuration and tie yield strength. Columns with 42 per cent higher amounts of transverse reinforcement than that required by seismic provisions of ACI 318-02 showed ductile behaviour. Relationships between the calculated damage index and the observed damage such as initial crack, spalling of concrete, buckling of longitudinal bar, and crushing of concrete are propose.

This paper aimed at the development of hydrophilic carbon fiber with improved tensile strength and ductility, numerous single fiber pullout tests from different cement matrices were performed. Fiber debonding and pullout have a large influence on the tensile stress - crack opening behavior of fiber concrete. Both debonding and pullout depend on the quality of the matrix, as well as on the embedded length of the carbon fiber. In this paper, all fiber pullout tests were carried out using high strength carbon fibers, both without fluorinationed and with fluorinationed carbon fiber.

In this studies, Dapped End Beams(DEB) having disturbed regions were designed by using strut tie model, and the main purpose of this paper is that whether T-headed bars and Steel fibers will be present or not. The ability of DEB with T-headed bars have a superior performance rather than others, such as improved ductility, larger energy adsorption and enhanced post-peak load carrying capability. The capacity of DEB with steel fibers also show increase of ductility, shear strength, fatigue strength and crack. Each DEB with both headed bars and steel fibers, headed bars, and steel fibers as a substitute reinforced steel in the disturbed regions and a DEB with only stirrup and tie reinforced steel were comparable. In contrast, the headed bar stirrups, the tie headed bars and the reinforced steel fibers did not lose their anchorage and hence were able to develop strain hardening and also served to delay buckling of the flexural compression steel. Excellent load-deflection predictions were obtained by increasing the tension stiffening effect to account for high load effects.

Recently, post tension flat plate slab system is widely used for a new slab structural system. Slab-column connections may fail in brittle manner by punching shear. Flat plate slabs have been widely used for gravity load resisting system in buildings. Lateral resistance usually provided by shear walls or moment resisting frames. Since plat plates move together with lateral loading system during earthquake or wind, it is important to evaluate the gravity resistance under a drift experienced by lateral force resisting system during either design earthquake or wind. Thus, this study investigated post tension flat plate slab systems whether they have sufficient strength and deformability to resist gravity loads during specified drift levels. Experimental research was carried out.

Recently, Many researchers are interested in ultra-high performance cementitious compostie characterized by high strength and high durability and trying to apply for structural members. In this paper, twelves fiber-reinforced UHPCC with high compressive strength over 150MPa I shaped beam without stirrups were tested under various conditicns to investigate the mechanical behavior of UHPCC I shaped beam without stirrups. Variables considered in this study includes steel fiber volume fraction, reinforcememt steel ratio, and shear spar ratio.

This study presents results from an experimental work for two normal prestressed concrete beams and three dual prestressed concrete beams. The dual prestressed concrete beams made with normal concrete in compression zone and high performance steel fiber reinforced concrete in partial depth of tension zone. Through cyclic loading test under low frequency, structural behavior and resistance to dynamic loading for dual prestressed concrete beams are investigated. Considerable increase of crack and yield load capacity of Dual prestressed concrete beam is shown compared with normal prestressed concrete beam. In addition, re-loading and un-loading rigidity of dual prestressed concrete beam under cyclic loading are increased comparing with normal prestressed concrete beam.

In the seismical capacity evaluation for RC structure wall-slab joint is very important factor. Because lateral load is resistance element and gravity load resistance element are acted mutually in the wall-slab joint. In this paper, to improve the seismic capacity of the wall-slab joint in the existing wall type apartments experiment which improve and retrofit a seismic capacity by unequal angle bracing and carbon sheet attachment are carried out. These methods are also economic and simple in mitigating seismic hazard, improve earthquake-resistance performance, and reduce risk level of building occupants. From the experimental results, the change of strength, degration of stiffness, and energy dissipation are evaluated. It can be concluded that these methods are effective in improving the seismic performance.

The short piers of bridge which is constructed by cantilever method may not be flexible enough to accommodate longitudinal movement of box girders. The constraint effects of longitudinal movement of box girders can introduce large stresses, and consequently large moments into short piers. This study is aimed at proposing a method to reduce moment of short piers in bridge constructed by cantilever method. Numerical analyses are carried out depending on the parameters such as control force and height of piers. Numerical results of the study represent that long-term moment of piers can be controlled effectively by employing the proposed method.

In bridge deck systems, deflections and cracking can be controlled by longitudinal and transverse prestressing, There are some benefits, longitudinal cracking control, the thickness reduction of deck slab, the widening of deck width and the reduction of the cross section area, in transversely post-tensioned concrete box girder bridges. However, it has been not sufficient to study the structural behaviors of transversely post-tensioned concrete box girder. Therefore, It is needed to predict the structural behaviors by prestressing and static loading. In this study, the analytical and experimental load tests are carried out to study the effect of transverse prestressing on concrete box girder. For these objectives, four test specimens are fabricated with various tendon spacing and steel ratio of top slab. The analytical and experimental studies are performed to estimate effects of the prestressing and failure tests.

Prestressing tendons in a nuclear containment building dome are non-axisymmetrically arranged in most cases. However, simple axisymmetric modeling of the containment has been often employed in practice, which requires the axisymmetric approximation of the actual tendon arrangements in the dome. A procedure was previously proposed that can implement the actual 3D tendon stiffness and prestressing effect into the axisymmetric model for CANDU type. This paper further verifies and compares some methodologies adopted in the proposed scheme through some numerical examples.

In this study, a simple moment-resisting precast concrete beam-column connection is proposed for highly seismic zone using dywidag ductile rod [DDC]. DDC is superior system for ductility, energy dissipation capacity, connection strength, and drift capacity. A study was carried out to investigate the connection behavior subjected to cyclic inelastic loading. Four Precast beam-column interior connections and one monolithic connection will be tested. The variables will be examined were the strength relationship between joint's ductile rod and beam reinforcement for gain energy dissipation capacity. The specimens will be tested only reverse cyclic loading in accordance with a prescribed displacement history. Connection performance is evaluated on the basis of ductility, energy dissipation capacity, connection strength, and drift capacity. the precast connection using DDC is capable of matching of exceeding the performance of the monolithic connection and thereby provides moment-resisting behavior.

Precast Segmental method was developed in germany 1950's. This method has been adoptted in long span girder mainly owing to easy construction effect. But, so far, The limit exists that this method is constructed in a portion of span and hard conveyance and foundation. This study was performed to analysis behavior difference of two rectangular section girder, spliced girder that was jointed 5-sliced 0.8m segment and monolithic girder that was produced in one body 4m span.

Since a ductile coupled shear wall system is the primary seismic load resisting systems of many structures, a coupling beams of these system must exhibit excellent ductility and energy absorption capacity. In this paper, the seismic response of coupled shear wall system is discussed. The cyclic response of steel coupling beams embedded into reinforced concrete boundary elements was studied. Three half-scale subassemblies representing a portion of a prototype structure were designed. constructed, and tested. The main test variables were the connection details of hybrid coupled shear wall. These efforts have resulted in details for increasing the seismic capacity of steel coupling beam in the seismic behavior of buildings.

Steel encased composite columns are widely used due to their excellent structural performance in terms of stiffness, strength, and ductility. However, experimental studies were usually for the columns having higher steel ratio $(3-4\%)$. There are two different design concepts for SRC columns. ACI-318 specifies the design strength of the column using the same concept of reinforced concrete columns. AISC-LRFD specifies the P-M diagram using the concept of steel column. In this paper, SRC columns have the steel ratio of $0.53\%\;and\;1.06\%$. From the test results, ACI-318 specifications showed better evaluation of SRC columns having low steel ratio. H beam and steel tube partially filled with concrete were embedded in concrete. Flexural tests showed considerably high ductility.

Composite beams are generally known to possess higher flexural stiffness and strength under the positive bending moments than the normal steel beams. However the these beams also exhibit large differences in flexural stiffness and strength when both positive and negative bending moments are applied. As observed during the 1995 Kobe Earthquake, these beams tend to be fractured on the bottom flanges under repeated cyclic loadings. The objective of this study is to develop and evaluate the composite beam detail, which is able to effectively resist the seismic loadings. The proposed system is composed of the slit on concrete slab around column. A limited experimental program was designed and conducted to investigate the hysteretic behavior of the proposed composite beam system. From the experimental data obtained from the testing of three specimens, the proposed composite beam detail is found to possess large beam rotation than normal steel beams.

In general, the nonlinear behavior of composite structures composing of steel and concrete is analyzed on the basis of the assumption of the perfect bond actions in steel-concrete interface in which the interface slip or separation is not allowed. The assumption is based on the fact that the full interface bond behavior is provided with the mechanical connectors of studs. However, since the number and spacing of the studs are determined by the stress resultants calculated in the interface area, the interface analysis is required to evaluate the stress resultants. This paper describes the nonlinear steel-concrete interface behavior considering the two interface failure mechanisms of slip and separation. Elastoplastic constitutive relation is developed. thru the formulation framework using the two energy dissipation mechanisms. As the result, the steel plate push-out tests sandwitched between concrete blocks are analyzed and compared with the test results with which the good agreements are observed.

It was found from the previous experimental studies that the long-term deformation of SRC columns was quite different from that of RC columns. A new approach method is needed to quantitatively predict the long-term deformation of SRC columns. In this study, the causes of the difference between the behaviors of RC and SRC columns are investigated and discussed. SRC columns exhibit a time-dependent relative humidity distribution in a cross section differently from that of RC columns due to the presence of a flange, which interferes with the moisture diffusion of concrete. This different relative humidity distribution may reduce the drying shrinkage and the drying creep in comparison with RC columns.

No specific guidelines are for computing the shear strength of steel coupling beam connections embedded in the reinforced concrete shear wall. In this paper, a theoretical study of the strength of hybrid coupled shear wall connections is achieved. The bearing stress at failure in the concrete below the steel coupling beam section is related to the concrete compressive strength and the ratio of the width of the steel coupling beam section to the thickness of the hybrid coupled shear wall. To revise factor affecting shear transfer strength across connections between coupled shear walls and steel coupling beam, experimental studies are achieved. The main test variables were auxiliary details of stud bolts. In this studies, these proposed equations are shown to be in good agreement with the test results reported in the paper and with other test data in the literature.

Up to now, many researches have been performed md verified that many properties of concrete can be improved by using mineral admixtures such as blast furnace slag, silica fume, and expansive admixture. But it is not clear whether there is any need for entraining air to make a high strength concrete using expansive admixture and mineral admixtures to insure enough freeze-thaw resistance. this paper presents the strength and durability properties of high strength concrete using expasive admixtures and industrial by-products. It was observed from the test results that very high strength concrete$(W/B=20\%)$ is not needed to be air entrained and high strength concrete$(W/B=30\%)$ using expansive admixture and mineral admixtures is needed to be entrained $2\~4\%$ air.

In this paper, a series of fracture tests are performed for the chemically prestressed steel fiber reinforced concrete (SFRC) manufactured with addition of expansive additives for the study of fracture behavior and characteristics. Cracking loads of the chemically prestressed SFRC are greater than that of normal concrete and those are also increased by increasing of steel fiber volume. Thus, it is necessary to obtain optimum steel fiber volume to induce chemically prestressing effectively to concrete members. The result of three-points bending tests shows that early-cracking resistance of the chemically prestressed SFRC is increased without increase of fracture energy. From the test, the tension softening curves are also obtained by poly-linear approximation method and simulated behaviors by using the determined tension softening curves agree with experimental results. And it is confirmed that cracking and ultimate behaviors of chemically prestressed SFRC can be predicted by using obtained fracture characteristics.

This study concerns the new estimated strength equation of concrete by penetration test. There are not only few estimate strength equations of concrete, but also many problems to apply them because of time, cost, easiness, structural damage, reliability and so on. In this study, there performed a series of penetration test with in 730days' concrete structures and proposed equations as follows; $$Linear\;:\;f_{ck}=2.95d-80.0(r^2= 69.8\%)$$ $$Quadratic\;:\;f_{ck}=0.204d^2-12.15d+193.2(r^2=83.6\%)$$ here, fck : Estimated compressive strength of concrete by MPa d: exposed probe length by mm.

This study concerns the new strength equation of concrete by ultrasonic pulse velocity test. There are not only few estimate strength equations of concrete by ultrasonic pulse velocity test, but also many problems to apply them because of time, cost, easiness, structural damage, reliability and so on. For this study, there performed a series of test and proposed equations as follows; $$Linear\;:\;f_{kc}=65.43Vp-207.18\;r^2=80.8\%$$ $$Quadratic\;:\;f_{ck}=42.35Vp^2-250.71Vp+378.8\;r^2=83.7\%$$ here, fck : Estimated compressive strength of concrete by MPa Vp: Ultrasonic Pulse Velocity of concrete by km/sec.

This study concerns the. new equation of concrete strength by schmidt hammer test. There are not only few estimate strength equations of concrete by schmidt hammer test, but also many problems to apply them because of time, cost, easiness, structural damage, reliability and so on. For this study, there performed a series of schmidt hammer test with in existing 730days' concrete structures and proposed equations as follows; $$Linear\;:\;f_{ck}=2.18R-40.54\;(r^2=77.7\%)$$ $$Quadratic\;:\;f_{ck}=0.076R^2-2.92R+40.04\;(R^2= 85.5\%)$$ here, fck : Estimated compressive strength of concrete by MPa, R : Rebound index of concrete.

Hydraulic structures have been constructed with low cost concrete so as to increase the investment efficiency. As the construction of agricultural irrigation and drainage project is concentrated on off-farming season and come to construction less than 28-day strength in quality control. As we are aware the major thrust construction of short period is now in hydraulic structures rather then the large- scale. This paper will propose the relationship between the 7-day and 28-day compressive strength of concrete be investigated. Test will be carried out on nine different concrete mixes and 180 core drilled form the hydraulic structures with 7-day and 28-day compressive strengths ranging approximately from 24 to 30Mpa.

Nowadays, there has been substantial interest in whether there is an association between electromagnetic field exposure and living environment. It is increased the demand that electromagnetic wave environment and its countermeasure. In the present study, we has applied the electromagnetic absorbent inorganic paint of 'I' corporations, and measured electromagnetic waves generated in new apartment before occupancy using the standard field electromagnetic wave generating device we developed. The measurement before occupancy was $100\~131V/m$, but the measurement after occupancy was $6.9\~8.0V/m$ less than 10V/m, the comprehensive electromagnetic wave limit allowed by TCO in Sweden. The implication is that domestic apartment are exposed to extremely poor electromagnetic wave environment. Nevertheless, there have been neither serious efforts to overcome this problem, nor its alternatives and related standards. Therefore, it is necessary to continue research of related fields to establish standards and plans to improve the situation.

The purpose is to prove the newly established 'UNBONDED CAPPING' method for Concrete Strength Tests. Day by day, concrete buildings and structure became high-rising and magnificently vast scheduled, as contributed from the development of improved equipments that suitable to specific construction works and high qualitied Admixture, the qualities of the concrete was highly improved. It is very important that the concrete strength tests and evaluation should be carried out in the manner that as soon as the concrete is placed so that dismantling form works can be done in time and that may enabling reducing construction period directly related with the costs of the project. However, the conventional capping method of concrete specimen requires more manpower and consuming times, As for the Sulfur capping, there may be incurred accidential fire and generation of Gas, what is more there stands limitation in precise evaluation of strength test results because of variation in capping method results may vary in concrete strength test results. Not necessarily emphasize, the compression strength of the concrete is the most valuable basic data essential to control the qualities of the concrete and that should be carried out accurately. in this study evaluation of the compressive strength test results comparing stabilized concrete capping method for Cement Paste capping, Sulfur-paste capping ,High Gypsum capping and recently flowing the Grinding with the UNBONDED CAPPING' method to provide reliable and economical concrete strength testing.

This paper reports the results of experimental study on the effects of replacement level of hwangtoh or slag on the flexural behavior of reinforced hwangtoh-concrete beams. All the beams were singly reinforced with longitudinal bar ratio p=0.5pb and were tested under two-point top loading. The flexural strengths obtained from tests, such as initial cracking strength, serviceability strength, maximum strength, were compared with ACI 318-02.

Most concrete is recently made of an aggregate which is properly absorbed. and carried in it in order to do capability at every fields. We have been close to demand new capability of high flowing and enduring for specific concretes. That is difficult to cope with claiming the efficiency on deterioration from lack of a high quality aggregate. Therefore. For solving the problems we apply to a packing method for using dried materials. That is to say it is a kind of making into an instant. In this study. There is a purpose to present fundamental data. comparing and analyzing a phenomenon about aggregate's absorption following the rate of adding water. for using existing materials.

If concrete structure is exposed to high temperature such as long-term fire, damages affecting partial or whole structure system may occur. Therefore accurate diagnosis of deterioration is needed based on mechanism of fire deterioration in general concrete structures. Fundamental information and data on the properties of concrete exposed to high temperature are necessary. Especially, the amount of fire damage done to concrete depends on the materials, the standard design compressive strength of concrete, and heated temperature. So, the object of this study is to present data for supposed heated Temperature of deteriorated concrete by fire.

The object of this study is vibrating compaction and curing method in the production process of Design concrete for precast concrete(Design-PC) product. From change of vibrating compaction time and pre-curing time, curing temperature which would be factors of product quality in Design-PC concrete production, and research of optimized steam curing condition from relations between curing condition and strength development, basic data of vibrating compaction time and concrete steam curing method for Design-PC will be presented.

Due to the demolition of old structures, primarily buildings, an amount of discharged construction wastes are increased. From the construction wastes, recycled aggregate can be used as a useful resource for concrete. However, its application to structural member is very limited. In this experimental study, the compressive strength of spun-concrete using recycled aggregate was investigated. Coarse aggregate was replaced with $100\%$ of the recycled coarse aggregate, and recycled fine aggregate was replaced with various amount. According to the test results, the specimen of spun-concrete showed uniform compressive strength regardless the amount of replaced recycled fine aggregate.

Recently, because of the shortage of natural aggregate and the environment regulation of government, the application of recycled aggregate by solution method is observed according as the concern for the reuse of waste concrete. But because the quality of recycled aggregate is poor and quantitative quality judgment standard of recycled aggregate is fluffy, construction field application is difficult. Therefore, this study compares and investigates effect that quality of recycled aggregate influencing recycled concrete. As the result of this study, the more quality of aggregate increases, the more recycled concrete quality increased and high quality recycled aggregate generally displayed performance of similar level with nature aggregate. But, durability of recycled concrete using recycled aggregate appeared lower than concrete using natural aggregate without reference to aggregate quality.

This study is contents about the method which separates ASCON, the tiles and the reds bricks in recycled aggregates. The method of separation used difference of specific gravity.

In these days the exhaustion of natural sand has been highlighted with the environmental damages due to excavating sea-sand. Many researchers and engineers have investigated some materials to replace natural sand with, and were interested in using the basic oxygen furnace-slag, the industrial by-product, as fine aggregate. One of the drawbacks to using BOF-slag as a aggregate is to be gradually expanded, and needed the time-consuming process, but some engineers in Korea tackled it recently. In this study, the stabilized BOF-slag was used for lean concrete under the laboratory condition. After testing the several properties - dry density, compressive strength, and young's modulus-, it was found that the dry density was proportionally governed by BOF-slag content and the 7-day compressive-strength was $110\~120\%$ of the natural sand-made. Therefore, BOF-slag is applicable to the lean concrete because they greatly satisfied the required strength, $50kgf/cm^2$.

The objective of this experimental study is to grasp the effect of replacement level of high-quality recycled aggregate on the properties of high-performance concrete. The mixing types were divided into two series based on containing $0\%\;and\;15\%$ fly-ash. Replacement level of recycled aggregate ranged from $0\%\;to\;100\%$. Test results showed that the initial slump and the fluid velocity were independent on the replacement level of recycled aggregate, and the loss of compressive strength was almost $20\%$ with the recycled aggregate only.

The effect of fly ash to prevent detrimental expansion due to alkali -silica reaction was investigated through the ASTM C 1260 method that is one of the most commonly used method because results can be obtained within about 16 days. Reactive aggregate used is a netamorphic rock and sedimentary rock. The replacement proportions of portland cement by fly ash were respectively 0, 5, 10, 15, 25 and 35 percent. Expansion of mortar bars due to alkali-silica reaction decreased with the increase of fly ash content. The results show that the expansion due to alkali-silica reaction is dramatically reduced in the presence of high volume fly ash. When the fly ash content examine from all angles (strength and a flow), the replacement proportions of fly ash is about $25\%$ in order to control on expansion.

This study bases on showing the pictures of how to keep a recycled fine aggregate well (quality control) and how to invent the measurement of mortar's quantities which largely effect on basic properties of matter: strength, durability and so on. As a result of the experiment by immersion, quantities of adhesive cement takes 7 to 8 days to stabilize by sulfuric. However, by hydrochloric acid, it takes a little quicker due to the first quick reaction, aggregate of the measurement of adhesive mortar by immersion used acid liquids are likely applicable following a suitable inspection and complementarity.

The objective of in this study makes investigation into the characteristics of concrete as to properties and blended ratio of crushed aggregates through experimental researches. In this research observed crushed quality characteristic of crushed aggregates that is produced in representative stony mountains of Busan suburbs (Yang-san, Kim-hea, Jin-hea). And wished to investigate the quality change and characteristics of concrete with variation of blend ratio of crushed sand(50, 60, 70, 80, 90, $100\%$). Measured the air contents and slump to investigate properties of fresh concrete, and unit weight and compressive strength in age of 7, 28, 60, 90 days to investigate properties of hardened concrete.

The increase of the use of recycled aggregate is necessary for the decrease of building waste, but it is not possible to use concrete because of the various range of quality. Therefore, the quality grade and application method of recycled aggregate should be prescribed before the site application so in that this study we investigated the effect of the quality of recycled aggregate on the compressive strength, resistance freezing and thawing. As results of this study, the compressive strength of recycled aggregate concrete used recycled aggregate, as if it had high quality recycled aggregate is similar or higher to that of crushed stone. Also, this high quality recycled aggregate affect the increase of resistance freezing and thawing.

The purpose of this study is recycling of sewage sludge and fly-ash. In this experiment, green aggregates, which is a mixture of sewage sludge and clay and fly-ash, with different content of sewage sludge (up to $80wt\%$). Then they were burned in different soak temperatures from $1190^{\circ}C\;to\;1290^{\circ}C$ with changed soak time and heating rate at 5, 7, 10 minutes and $20^{\circ}C/min$, $30^{\circ}C/min$ respectively in order to produce lightweight aggregate (LWA). Data of both experiment series were generated to evaluate the quality of LWA as well as the relationship between burning condition and product's quality.

The purpose of this study is to recycle waste concrete and reuse reclaimed asphalt concrete as a concrete coarse aggregate. In this experiment, recycled coarse aggregate was substitute for natural crushed aggregate at the rate of 0, 30, $50\%$, and reclaimed asphalt concrete was substitute for recycled coarse aggregate at the rate of 0, 10, 20, $30\%$. According to the experimental results, as the reclaimed asphalt concrete content has influence on the properties of recycled aggregate concrete such as compressive and tensile strength, the criteria for the substitute ratio should be required to be set.

Recent economic development caused a vast use of mineral resources in Korea. Consequently, a supply of poor quality course aggregate (poor particle shape as well as poor gradation) in construction material become a social problem. In this study, an effect of aggregate particle shape on property of concrete was evaluated. The flat and elongation ratio of crushed aggregate was controled to 8, 15, 25, 35, and $47\%$ in order to evaluate fresh concrete behavior as well as physical properties in hardened concrete. Test result shows a poor aggregate particle shape cause a significant increase in entrapped air in fresh concrete, while no significant effect on hardened concrete property, such as strength as well as stiffness. This increase in entrapped air, however, believed to cause a significant decrease in concrete durability.

Aggregate occupies about 70 to 80 percent by volume in concrete as skeleton of concrete, but recently, it has been insufficient in quantity to collect good natural aggregate because of exhaustion of aggregate resources. In case of Korea, in 2002, the using ratio of crushed stone occupies about $97\%$ of whole coarse aggregate, and ratio of crushed sand occupies about $18.3\%$ of whole fine aggregate. This is an experimental study to compare and analyze the properties of concrete according to the grading of crushed stone to improve quality and mix design of concrete using crushed stone. According to results, it was found that grading level of crushed stone in the range of G42 to G60 was better than any other grading level in terms of fluidity and compressive strength. And it is considered to be in the range of 6.52 to 6.85 in terms of FM.

Metakaolin is a cementitious material for producing high-strength concrete. This material is now used as substitute for silica-fume. In this paper, we did the durability test such as chloride ion diffusion, chemical attack. repeated freezing and thawing, carbonation. In the chloride ion diffusion test, according to the increase of substitute of metakaolin & silica-fume for binder, the diffusion coefficient is more reduced. And in the chemical attack test, according to the increase of substitute, the resistance is more excellent. In the other durability test, the concrete using metakaolin is also compared with those of the portland cement concrete and silica fume concrete. According to these tests, we recognized that metakaolin is able to be used as a substitute for silica-fume.

Several factors of concrete durability decline factor are acted as complex deterioration and is happened not that happen by simplicity deterioration. Specially, in case of sea construction, as complex salt damage, carbonation and freezing & thawing, concrete surface and pore structure is deteriorated. Therefore, analyzing concrete carbonation and pore structure after freezing and thawing test by fresh water and sea water in this research, we wish to study about acceleration of decline of durability and complex deterioration by concrete surface deterioration in sea environment.

In order to estimate the chloride ion penetration, the model, which considers diffusion and sorption, is proposed on the basis of Finite Element Method (FEM). The FEM program provides the estimation of chloride concentration according to cyclic humidity and sorption. After the humidity diffusion analysis is carried out, the chloride ion diffusion and sorption analysis are conducted on the basis of the preestimated humidity data in each element. Each element has different analysis variables at different ages and locations. At early ages and constant outer humidity, the difference between inner and outer relative humidity causes the chloride ion penetration by sorption. As the humidity diffusion reduces the difference with age, the effect of sorption on the chloride ion penetration decreases. By the way, the cyclic humidity increases the effect of sorption on the chloride ion penetration at early ages, and the quantity of chloride ion around steel at later ages. Therefore, the in-situ analysis of chloride ion penetration for marine concrete structures must be performed considering the cyclic humidity condition and the long term sorption.

In order to ensure the construction of sustainable reinforced concrete structures, durability evaluation of RC structures before construction should be carried out. In this paper, a service life evaluation technique using a safety factor determined by a reliability theory for RC structures subjected to chloride attack is proposed. The life safety factor and the service life evaluation .proposed in this paper can be applied consistently for the durability evaluation of recently developed Korean standard specification for durability of concrete structures which be used effectively for the evaluation before construction and maintenance for RC structures under chloride attack.

The purpose of this paper is to evaluate performance on reducing the chloride diffusion of surface treatment systems with elapsed time, treatment thickness, treatment frequency, and the types of surface treatment - coating, penetrator, and both all. Based on this paper, the guideline to applicate surface treatment systems will be established and comprehended how effective the resistance of chloride diffusion is. The selection of surface treatment materials and thickness to acquire service life of target will be possible. It is also expected to select optimum surface treatment system groups to resist chloride diffusion effectively and to estimate increased service life as the effect of durability enhancement.

When the concrete structures are in contact with seawater, concentration of chloride for estimating chloride diffusion coefficient can be defined as the chloride concentration of sea water. However, in case the concrete structures, constructed in the seashore, aren't directly in contact with seawater, it is difficult to establish the interface concentration of chloride. In addition, marine concrete structures are greatly affected by salt attack such as rebar corrosion, among the cause of salt attack, airborne sea salt is primary factor. Therefore, in this study, salt attack environment by airborne sea salt was investigated in terms of a seasonal distribution at 33 spots, 6 areas in the East, West, South coast for 1 year. Results indicated that in the South coast, the amount of the airborne sea salt is comparatively higher in summer. in the West coast. higher in winter. On the other hand, in the East coast, the amount of the airborne sea salt is rarely affected by a season.

The evaluation of Single or multi-degregation of concrete coated by high performance surface penetration agency was examined through various tests, i.e., carbonation, absorption, carbonation + chloride ion and carbonation + chemical solution according to various high performance surface penetration agencies and various compressive strengths of base concrete. The 2 types of high performance surface penetration agencies were used i.e., inorganic and alcohol soluble. And 2 types of compressive strength of base concrete were used such as 21 30. MPa. The characteristics of concrete coated high performance surface penetration agency was more improved than that of non-coated concrete, and especially, water soluble inorganic agency was most effective. And if compressive strength of base concrete was low, the improved effects would be larger.

The prediction of the strength of cold weather concrete and the analysis of the insulating material effect were performed to apply the prediction function with maturity concept for quality control of them in this study. The several results driven from above processes were summarized as followings. First, the difference between the temperature of cylinder covered with insulating materials and that of cylinder without them was $4.5\~6.0^{\circ}C$. Second, the maturity of concrete was suggested to be keep higher than $96\~115^{\circ}C{\cdot}D$ until at least 7-day and the temperature of fresh concrete was suggested to be keep above $10^{\circ}C$ directly after set.

Chloride ion diffusion is the most important thing of occuring deterioration in RC structure. According to establish data, the curing time in concrete reduce the chloride ion diffusion coefficient. The purpose of this study is to make clear through experience on the effect of curing time on the chloride ion diffusion coefficient in concrete with Portland cement and ground granulated blast-furnance slag and a propose the standard of chloride ion diffusion coefficient in concrete.

Recently, construction works of scale are getting larger with economic growth. Shotcreting is one of major processes in tunnels construction. Accelerator is used in tunnel and underground structures to ensure early strength of shotcrete. Silicate based accelerator and aluminate based accelerator is getting widely in the field. But these accelerators have many problems due to decesase of long-term strength and low quality of the hardened shotcrete. in order to solve these problems, recently developed powder types cement mineral accelerator. In this study, we tested chloride permeability, freezing and thawing and accelerated carbonation of shotcrete. As a result of the test, wet-mixed shotcrete with powder types cement mineral accelerator exhibited durability improvement compared to the conventional shotcrete accelerator.

The durability and water - resisting capability of nuclear concrete structures can be greatly improved as the density of concrete surface increases. Applying the surface penetration sealer to the concrete surface can increase the surface density. Therefore, the objective of this study is to identify the most suitable surface penetration sealer based on lab test. The considered parameters rate and water resistance and absorbance rate of the concrete specimen after the penetration sealer are applied. The experimental study resulted in the identification of the two most suitable surface penetration sealer based on their performance.

In this study, the experiment was carried out to investigate and analyze the strenth properties and flowability of ultra-high strength concrete accroding to types of mineral admixtures and cements. The main experimental variables were water/binder ratio $25.0\%$, water content $160kg/m^3$ and mineral admixtures such as fly ash, silica fume and meta kaolin. According to the test results, the principle conclusions are summarized as follows 1) In case of using admixtures, superplasticizer amount need more than plain concrete. 2) According to kinds of admixtures and cements, the viscosity of concrete show much difference. 3) The autogeneous shrinkage of ultra-high strength concrete is profitable that use admixture, and heat of hydration is desirable that apply considering countermeasure enough in the advance. 4) Meta kaolin is excellent in side but has viscosity enlargement efficiency a little. But, problem estimates that is not to make design strength to and $70N/mm^2$ if use mixing condition with water-binder ratio properly.

Plastic shrinkage cracking is a major concern for concrete, especially for flat structures as highway pavement, bridge deck slabs, and bridge deck pavement. LMC(Latex Modified Concrete) be used mainly for bridge deck overlays, so occurrence possibility of plastic shrinkage cracking is very high. But LMC is form a close-packed layer of polymer particles in very early time from the time of adds the latex and water. So plastic shrinkage cracking compare with normal concrete is not occur at final setting time. Results indicates that LMC is advantage to prevent occurrence of plastic shrinkage crack and it's possible co construction for bridge deck overlay effectively.

After concrete casts, temperature decent and shrinkage bring volume changes of concrete pavement. Microcracking and cracking in concrete pavement are caused by these volume changes. As a result, durability of concrete pavement is deteriorated. Recently, Very-Early Strength Latex Modified concrete(below:VESLMC) from the beginning of High-Way is used as urgent repair material for bridge deck. The advantage of VESLMC is that compressive and flexural strength at 3 hours age are 4.5MPa and 21MPa respectively. It allows the traffic to open in 3 hours. But, this material has the problem which is early-age shrinkage cracking caused by water self-dissipation with rapid hydration reaction and water evaporation with body dry. Unfortunately, until now, the research about early-age shrinkage of VESLMC leaves something to be desired. Therefore, the purpose of this study is to present the early-age shrinkage of VESLMC respect to latex contents and shrinkage ratio to maximum length change that can help field engineers' skill. Latex contents of 0, 5, 10, 15, $20\%$ in standard of same workability in VESLMC are selected by experimental variables. After initial set, shrinkage value was measured with 10mm LVDT for 3 days. The results of maximum shrinkage ratio were 0.019, 0.017, 0.023, $0.027\%$ respectively.

Recently. cold weather constructions were popularized because of the importance of construction term. The special method about mix design and curing of concrete was being planned to conduct cold weather constructions, but these method were not considered in a low temperature time. A Strength revelation of concrete is delayed in a curing condition of low temperature. If a construction was loaded in this case, cracks or remaining deformations are generated in a construction. So, a strength revelation characteristic in early age was investigated to secure early strength of concrete in curing condition of a low temperature. In this study, the method about concrete mix design was presented to secure construction safety in a low temperature time.

Recently, as structure is more higher and bigger, we need high strength and high performance concrete. Therefore it is necessary superplasticizer for high strength and high performance concrete. In this study, it is examined the properties of flow, air content and strength of concrete with polycarboxylate superplasticizer in comparison with existing superplasticizer. First, The slump loss of concrete used polycarboxylate superplasticizer showed 2cm until 120 minutes. Second, The air content loss of concrete used polycarboxylate superplasticizer showed $1\%$ until 120 minutes. Third, It is possible to manufacture $1000kgf/cm^2$ strength concrete using polycarboxylate superplasticizer with $806kg/m^3$ cement content, $18\%$ water-binder ratio, $15\%$ silica fume, $10\%$ fly-ash content.

The most important reason of using of ultra high strength concrete in super tall building is that ultra high strength concrete can reduce the section of members and control side sway effectively. However, the practical utilization of ultra high strength concrete is dependent not only on the production techniques, but also the overall preparation including proper code provisions, construction technique. The purpose of this study is to evaluate of mechanical properties of UHSC, such as modulus of elasticity, stress-strain behavior, modulus of rupture and tensile splitting strength. It is similar to normal or high strength concrete but necessary to discern the difference between normal or high strength concrete and ultra high strength concrete and modify existed equations. And in this study another important factor is to discern the difference according to member size, curing method in ultra high strength concrete experimentally.

Generally, the autogenous shrinkage of high performance concrete is important in that it can lead the early cracks in concrete structures. In the previous study, The. autogenous shrinakge of HPC was found to decrease with incresing expansive additive and shrinakge reduction agent. In case of combined use, the autogenous shrinakge was more reduction than in case separate use. The purpose of this study is to derive a realistic equation to estimate the autogenous shrinakge model of high performance concrete with exapnsive agent and shrinakge reduction agent. investigated the durability of high performance concrete using expansive additive and shrinkage reducing agent. The proposed equation showed reasonably good correlation with test data on autogenous shrinakge of high performance concrete with material for shrinkage reduction.

This study was performed to know effective control of crack occurred by hydration heat, restraint of multiplication of hydration heat, through mechanical test, strength test and crack control test using fluosilicate salt based anti-crack agent made from by-product during phosphoric acid manufacturing process. Mix proportions for experiment were modulated at 0.495 of water to cement ratio and addition amount of fluosilicate salt based anti-crack agent to $1.0\%$. Condensation time was late and compressive strength of hardened concrete cured at several days was executed to evaluate characteristics of crack control for concrete. It is ascertained that characteristics of crack control for concrete could be improved by an adequate addition of fluosilicate salt based anti-crack agent.

In this study, to investigate autogenous shrinkage behavior of 120MPa UHSC at early ages, free and restrained shrinkage tests are performed for various strength levels(50MPa, 80MPa, 120MPa). For 120MPa, the effect of fly ash on autogenous shrinkage was also investigated. In order to assess the potential for early-age cracking in concrete and a mixtures susceptibility to shrinkage cracking, restrained ring test was carried out. Test results show that autogenous shrinkage of UHSC was much higher than that of HSC, VHSC and fly ash delayed cracking age in UHSC by decreasing autogenous shrinkage.

The purpose of this study reutilization of waste fine tailing as admixture for cement. We observe tailing's basic properties such as shape, physical and chemical basic features. Also, various admixtures were made of 2 Types of tailings, OPC, fly-ash and blast furnace slag. The basic properties of the cement mortars incorporation with these admixtures were examined and analyzed under a verity of experimental conditions. This work showed that the tailing separated coarse materials could be effectively utilized as replacement materials of cement without any decrease in the strength if we can control the blaine of materials like OPC, slag and fly ash.

The objective of this study is to evaluate the physical properties of ultra fine-ground cement for grouting materials. This study investigates the compressive strength of cement paste, homogenized gel and solidified soil matrix with ultra fine-ground cement. Also It is estimated the injection properties of ultra fine-ground cement. From the test results, the compressive strength of ultra fine-ground cement is higher than that of portland cement. The injection properties are sufficient to apply silt-sand soil and minute-cracked rock bed. Also the properties of soil stability like water permeability coefficient are enough to be adapted various grouting specification.

Cold weather concrete is the concrete which is used during construction under low-temperature' environment, and this kind of concrete has to be taken care not to be frozen in early ages of setting-hardening, It is specified in the Concrete Standard Specification(2003) as 'the cold weather concrete must be used on the weather condition under the average daily outdoor temperature below $4^{\circ}C$.' In this research, the mechanical characteristics and hydration heat on the cold weather concrete using high early strength portland cement were studied. As a result, the excellent quality was obtained and high early strength portland cement is expected to be used widely as the cold weather concrete.

The hydraulic structure of the hydroelectric power plant such as aqueduct tunnels and the drainage canal became old. Therefore, because the concrete surface of the aqueduct tunnel has received severe damage by wear-out and the crack etc the repair is demanded. This research examined the applicability of the repair mortar which mixed the fly ash and an artificial aggregate by using the very high early strength cement. As a result, good Quality repair mortar which satisfied the demand performance more than self-flow 270mm and compressive strength $50N/mm^2$ (age of 28days) adjusting of water cement ratio by using the MTX cement be able to be manufactured.

In this paper, it was assessed durability of ultra-high strength cementitious composites(UHSCC) with the range of 180MPa of compressive strength through the test method of chloride ion resistance, carbonation, freezing-thawing resistance, permeability. In order to compare with ultra-high strength cementitious composites, normal concrete and high-strength concrete were also tested. As the experimental result, it showed that UHSCC was cleary superior to the durability performance of normal concrete and high-strength concrete.

The setting time is very important factor affecting the quality of tunnel lining and reinforcement of sloped slope etc. Currently, however, the quality criteria of accelerating admixture to improve it is not established well. In this study, evaluation on setting time measuring methods of a cement accelerating admixture was performed. Six types of measuring methods were checked and a proper measuring method of the admixture were proposed as fellows: (1) the temperature of materials used shall be controlled exactly and (2) to evaluate the properties of it, an admixture usage of $5\%$ (ratio of cement weight) is recommended.

The discharge of fly ash that is produced by coal-fired electric power plants is rapidly increasing in Korea. The utilization of fly ash in the raw materials would contribute to the elimination of an environmental problem and to the development of new high-performance materials. So it is needed to study the binder obtained by chemically activation of pozzolanic materials by means of a substitute for the exiting cement. This paper concentrated on the strength development according to the kind of chemical activators, the curing temperature, the heat curing time. Also Scanning electron microscopy and X-Ray diffraction analysis show what the reaction products of the alkali activated fly ash are.

According to demand the increase of the rate of strength development for rapid constructions and repairs, many efforts have progressed to improve on performance of concrete. The use of regulated set cement helps make it possible to increase the rate of strength development. However it has some problems as like increasing its permeability and accelerate its long-term deterioration caused by internal and external factors. The purpose of this study is to improve the performance of regulated set cement, which mixed with the mineral admixtures. In this paper, setting time, compressive/flexural strength and chloride permeability of mortar according to the substitute ratio of SF, FA and BS in the range of $5\~20\%$ were conducted. Based on the test results, 5% substitute of silica fume for binder was showed good performance.

This study aims to manufacture non-sintering cement(NSC) by adding phosphogypsum(PG) and waste lime(WL) to granulated blast furnace slag(GBFS) as sulfate and alkali activators. This study also investigates the pore structure of NSC Matrix. The result of experiment of pore structure properties, showed no considerable difference for total pore volume by cement mixing ratio but shows a large distinction in distribution of pore diameter. On the whole, pore-diameter of paste of NSC show that occupation ratio of pore diameter below 10mm is larger and is smaller than OPC and BFSC at pore diameter of over 10nm. Such a reason is that the hydrate like CSH gel and ettringite formed dense pore structure of NSC matrix.

In this study focuses on bond properties of hybrid FRP rebar after chemical environmental exposure. Hybrid FRP rebar bond specimens were subjected to four type of exposure conditions. Bond properties were investigated by direct bond test. Bond test results, hybrid FRP rebars were found to have better bond strength with concrete than currently using GFRP rebar. Also, hybrid FRP rebar had more than about $80\%$ in bond strength of steel rebar.

In recent days, the beneficial effects of using fiber reinforced concrete, especially Steel Fiber Reinforced Concrete, have been on the rise. However, few studies on long-term behavior of SFRC are executed in spite of great demand of SFRC. The fact that SFRC is far better than NRC in various properties such as tensile strength, ductility, flexural toughness has been certified by many researchers. And, those advantages can be also applied to decrease the structures deterioration induced by creep and shrinkage. Furthermore, even though it is fact that SFRC is generally used in joint members to distribute concentrated stresses by fibers, SFRC is treated as NRC in designing especially for long-term behavior of structures. So this paper is about a study on the long-term response of SFRC applied to HPC about 40MPa. Therefore, in this paper, the test results of eighteen high-strength concrete specimens and steel fiber-reinforced concrete specimens, with steel fiber content of $1\%$ by volume were presented. The test result shows that SFRC is advantageous rather than NRC in long-term response.

In the present research, slump, modulus of rupture (MOR) and flexural toughness $(I_{30})$ of high performance hybrid fiber reinforced concrete (HPHFRC) mixed with micro-fiber (carbon fiber) and macro-fiber (steel fiber) and replaced with silica fume were assessed with the analysis of variance (ANOVA). Steel fiber was a considerable significant factor in aspect of the response values of MOR and boo Based on the significance of factors related to response values from ANOVA, following assessments were available; Slump decrease: carbon fiber >> steel fiber > silica fume; MOR: steel fiber > silica fume > carbon fiber; $I_{30}$: steel fiber > carbon fiber > silica fume. Steel fiber $1.0\%$, carbon fiber $0.25\%$ and silica fume $5.0\%$, and Steel fiber $1.0\%$, carbon fiber $0.25\%$ and silica fume $2.5\%$ were obtained as the most optimum mixture.

In this study, an effect of fiber blending on material property of hybrid fiber reinforced concrete (HFRC) was evaluated. Also, optimized association and the mixing rate of fiber for HFRC was determined. Test result shows, in the case of mono fiber reinforced concrete, use of steel fiber in concrete caused increment in tensile and bending strength as the blended ratio increases, while use of carbon fiber and glass fiber caused increment in compressive strength. Use of hybrid fiber reinforcement in concrete caused a significant influence on its fracture behavior; consequently, caused increase by mixing rate of steel fiber and contributed by carbon fiber, glass fiber, celluloid fiber in reinforcement effect in order.

In this study, a strut-and-tie models for the coupling beam based on deformations are presented. To design shear-dominated R/C coupling beams, it is important to consider shear strength deterioration with required deformations. This study proposes the method of estimating shear strength of the reinforced concrete coupling beams. The proposed method determines the strain states from target displacements based on the nonlinear truss analysis. The estimated horizontal strain of beam is then used in calculating the strength of the diagonal strut with compatibility conditions. The deterioration of shear strength of the coupling beam depends on the strength degradation of struts due to plastic deformations.

Nonlinear numerical analysis was performed to investigate the behavioral characteristics and failure mechanism of flexure -dominated structural walls with partially confined boundary elements. Based on the results, deformability of walls with partially confined boundary elements was evaluated, and a design method which can determine depth of confined boundary element according to given ductility demand, was developed. Also, effective details of laterally confining re-bars were proposed for boundary elements with rectangular cross-section. The design method can be used to choose the spacing of confining re-bars assuring the confining effect and constructability.

Estimation of deformation capacity of non-flexural reinforced concrete members is proposed using basic concepts of limit analysis and the virtual work method. This new approach starts with construction of admissible stress field as for an equilibrium set. Failure mechanisms compatible with admissible stress fields are postulated as for displacement set. It is assumed that the ultimate deformations as result of failure mechanisms are controlled by ultimate strain of concrete in compression. The derived formula for deformability of deep beams in shear shows reasonable range of ultimate displacement.

This paper predicts the shear stress-strain relationship of reinforced concrete columns using Transformation Angle Truss Model (TATM) considered bending moment and axial force effects. Nine columns with various shear span-to-depth ratios and axial force ratios were tested to verify the theoretical results obtained from TATM. Shear stress-strain relationship obtained from TATM was agreed well with test results conducted by bis study than other truss models.

This paper deals with the verification of the new truss model that has been conceptually derived and formulated in preceding research. Since the model includes the arch $coefficient-\alpha$, the characteristics of this coefficient are examined, and it appears that the $coefficient-\alpha$ is a function of a/d, $\rho$ and $\rho_v$. The arch $coefficient-\alpha$ is applied to the test specimens available in literatures, and the predicted values are shown to be in excellent agreement with the experimental results.

The design process of RC Slab includes multiple procedures such as structural analysis, member design, the production of calculation sheets, CAD, and itemized statements of quantities. The objective of this study is to develope an integrated design system that includes all the steps needed for RC Slab design, and as a result, to improve the quality and efficiency of the design process. In this study, the design steps are divided into structural modules and database, and each module and database is systematically combined for the complete design process. The developed design system is based on Web environment. Therefore it can be used in real time and reduces the design work time and space.

The designer has difficulty due to inadequacy of provisions in the domestic design code and lack of understanding for behavior of D-region. The rectangular shaped corbel consist 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, rectangular shaped corbel 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. The results show that strut-tie model can be a rational and an economical design than current conventional design methods.

Reinforced concrete deep beams are commonly used in many structural applications, including transfer girders. pile caps, foundation walls. and offshore structures. In this paper. the shear behavior and reinforcement effects of simply supported reinforced concrete deep beam with variable depth subject to concentrated loads have been scrutinized using strut-and-tie model to verify the effects of variable depth. The analysis results show that strut-and-tie Model of ACI 318-02 code is very effective method to design of simply supported reinforced concrete deep beam with variable depth.

Delaying and objection for the construction of storage spent-fuel disposal has prompted to consider expanding on-site storage of spent reactor fuel since it can eliminate the need for costly and difficult shipping and control of the spent fuel completely under the direction of the owner-utility. The dry storage unit developed in Canada can accommodate Korea heavy water reactor fuel elements and become a candidate for the Korean market. In this paper, finite element analyses were carried out in order to investigate the structural behavior of the nuclear spent fuel dry storage system, which is subjected to impact loads such as collision of a truck load and dropping of flask under the irregular operation.

To understand of size effect in high-strength reinforced concrete continuous deep beams, 6 specimens with section overall depth ranging from 400 to 720mm were tested. Test results indicated that the size effect of continuous deep beams is slightly greater than in simply supported deep beams.

An accurate and rational analytical proposal for determining the shear strengths of interior beam-column joints is presented in this paper. The proposed equation is derived using a compatiblity aided truss model theory. The accuracy of the proposed equation was checked by comparing calculated shear strength of joints with experimental results reported papers in literature. The comparison showed that the proposed equation predicted the experimental shear strength of joints with reasonable agreement.

The objective of this experimental study is to understand the shear behavior of reinforced concrete continuous deep beams. The main variables considered were concrete strength and shear span-to-depth ratio. Specimens of 4 two-span continuous deep beams were tested and compared with the strength of simple span beams. The results show that the influence of concrete strength on the shear strength of continuous deep beams is comparable to that on simple span deep beams. However, the effect of span-to-depth ratio is significantly greater than simple span deep beams.

This research aims to estimate the shear strength of the composition of prestressed hollow-core slab and steel beam. The shear strength of prestressed hollow-core slab combined with the steel beam decreases, as the beam deflection increases to a considerable extent. Existing studies on the shear strength of prestressed hollow-core slab are mostly limited to 265mrn- and larger thickness slab on concrete beam. This study investigates the slab of 100mm-thickness combined with steel beam instead of concrete beam. Five shear connector methods are proposed and the shear strength is estimated with or without the beam deflection for each composition method, respectively. Finally the reduction coefficient $(\beta)$ for the transverse shear stress$(\tau_{zx})$, which is critical for the failure of prestressed hollow-core slab, is proposed.

In recent years, the use of fiber reinforced polymer (FRP) composites to repair or strengthen existing reinforced concrete (RC) structures is increasing In order to evaluate the shear strengths of RC structures strengthened by FRP composites, it is needed to understand the shear failure modes of these structures. This paper presents a rational equation to distinguish the shear fail modes of RC structures strengthened by FRP composites using the compatibility aided truss models.

The current design procedures of ACI 318-02, CE3-FIP and NZS 3101 for interior beam-column joints do not provide engineers with a clear understanding of the physical behavior of beam-column joints. In this paper, the failure strengths of the interior beam-column joint specimens tested to failure were evaluated using the 3-dimensional strut-tie model approach, design criteria of ACI 318-02, ACI-ASCE committee 352 and Park and paulay, and softened strut-tie model approach. The analysis results obtained from the 3-dimensional strut-tie model approach were compared with those obtained from the other approaches, and the validity of the approach implementing a 3-dimensional strut-tie model was examined.

Over last decade extensive researches have been undertaken on the strength behaviour of Fiber Reinforced Concrete(FRC) structures. But the use of Ultra-High Strength Steel Fiber Cementitious Concrete Composites is in its infancy and there is a few experiments, analysis method and design criteria on the structural elements constructed with this new generation material which compressive strength is over 150 MPa and characteristic behaviour on the failure status is ductile. The objective of this paper is to investigate and analyze the behaviour of reinforced rectangular structural members constructed with ultra high performance cementitious composites (UHPCC). This material is known as reactive powder concrete (RPC) mixed with domestic materials and its compressive strength is over 150MP. The variables of test specimens were shear span ratio, reinforcement ratio and fiber quantity. Even if there were no shear stirrups in test specimens, most influential variable to determine the failure mode between shear and flexural action was proved to be shear span ratio. The characteristics of ultra high-strength concrete is basically brittle, but due to the steel fiber reinforcement behaviour of this structure member became ductile after the peak load. As a result of the test, the stress block of compressive zone could be defined. The proposed analytical calculation of internal force capacity based by plastic analysis gave a good prediction for the shear and flexural strength of specimens. The numerical verification of the finite element model which constitutive law developed for Mode I fracture of fiber reinforced concrete correctly captured the overall behaviour of the specimens tested.

This paper describes a proposal for crack width and deflection in RC flexural members. Because the serviceability provisions of the current codes are mainly based on only empirical relationships developed from test result and effective moment of inertia, crack width and deflections are contrary to the actual values. Based on nonlinear bond characteristics, tension stiffening effect, arch action and effective concrete tensile area. Then an equation is developed for predicting crack width and deflection in flexural members. The predicted results shows that as proposed model employed, crack width and deflections are different from estimated by the current KCI, MC 90 and EC 2 provisons, and the values predicted are in good agreement with experimentally measured values.

The Prestressed concrete girder bridges(PSC girder bridges), consisting of prestressed concrete girders and cast-in-place deck slabs, are sensitive to creep and shrinkage of concrete. Shrinkage and creep produce additional internal forces md deformations in PSC girder bridges. The long-term behavior of the PSC girder bridges depends on time-dependent properties of materials, amount of prestressing, methods and sequences of construction and age at loading. The purpose of this study is to predict the long-term behavior of PSC girder bridge. For this purpose, Computer program for Time-dependent analysis of PSC girder bridge has been developed. thereafter, Time-dependent analysis using developed computer program was carried out about 3-span continuous PSC girder bridges. Various construction timing sequences were used for parametric study.

Model updating is a very active research field, in which significant efforts has been invested in recent years. Model updating methodologies are invariably successful when used on noise-free simulated data, but tend to be unpredictable when presented with real experimental data that are-unavoidably-corrupted with uncorrelated noise content. In this paper, Reanalysis using frequency response functions for correlating and updating dynamic systems is presented. A transformation matrix is obtained from the relationship between the complex and the normal frequency response functions of a structure. The transformation matrix is employed to calculate the modified damping matrix of the system. The modified mass and stiffness matrices are identified from the normal frequency response functions by using the least squares method. Full scale pseudo dynamic pier test is employed to illustrate the applicability of the proposed method. The result indicate that the damping matrix of correlated finite element model can be identified accurately by the proposed method. In addition, the robustness of the new approach uniformly distributed measurement noise is also addressed.

Nonlinear finite element analysis is conducted to predict the structural behavior of precast concrete column and steel beam connected by using bolted connections. The Nonlinear FEM program is based on the modified compression field theory which has good accuracy in the concrete structures. The link element is properly used to model the discontinuity between precast concrete column and steel beam. Predictions from the proposed model are compared with experimental results and it is concluded that structural behaviors of the composite structures, such as strength capacity, crack pattern and failure mode, can be predicted quite successfully.

This paper discussed finite element method(FEM) models of the reinforced concrete rectangular shear walls with opening configuration and analysed under constant axial and monotonic lateral load using ABAQUS. The research comprises constitutive models to represent behavior of the materials that compose a wall on the basis of experimental data, development of techniques that are appropriate for analysis of reinforced concrete structures, verification, and calibration of the global model for reinforced concrete shear walls of increasing complexity. Results from the analyses of these FEM models offers significant insight into the flexural behavior of benchmark data.

The safety of buildings is generally estimated by analyzing a plane frame ignoring a minor bending moment. In this paper, uncertainties of reinforced concrete shear wall subjected to a biaxial bending are considered. First, major parameters are selected from all parameters of general shear wall design to perform a reliability analysis in their practical ranges, means and standard derivations of selected design parameters for the reliability analysis are calculated by a data mining as a simulation method. The bi-section method is used to find inclined neutral axis and its limit state using MATLAB subjected to the concept on strength design method. The reliability index $\beta$ as a safety index is calculated based on AFOSM(Advanced First-Order Second Moment) method. Also, if target reliability index $\beta_T$ is decided by an engineer an amount of reinforcement can be calculated by subtracting the reliability index $\beta$ from the target reliability index $\beta_T$.

In this study, dual composites concrete beam(DCC beam) partially superseded with steel fiber reinforced concrete in tensional part and normal strength concrete in compressive and remaining part is proposed. Based on flexural test under static loads, structural behaviors under repeated loads are investigated.

This paper presnets the tensile behavior of 8 high performance fiber-reinforced cementitious composites (HPFRCCs) members, each reinforced with one deformed bar 16mm in diameter. The variables included HPFRCC(Ductal, steel cord and polyethylene hybrid fiber, PE fiber) versus normal concrete. Fibers used in HPFRCC significantly increased tensile strength, ductility, and tension stiffening of cementitious materials. For HPFRCC, after first cracking, tensile load continue to rise without fracture localization. Sequentially developed parallel cracks contributed to the inelastic strain at increasing stress level. After yielding of the reinforcing bars, HPFRCC showed increases in loads with increasing strains.

Recently, bridge deck overlay with latex modified concrete is widely applied in domestic. the capacity of bridge deck overlay depends on bond state on the surface. factors that have an effect on bond state are clean condition on the surface, absence of surface microcracking, absence of laitance, overlay curing. In this study, it is researched that characteristic of bond strength according to moisture condition on the surface and the removal method of concrete. As a result, it shows high bond strength in dry condition when w/c is $31\%$ and in moisture condition when w/c is $38\%$ respectively. characteristic of bond strength according to the removal method of concrete shows high bond strength when using water-jets rather than jackhammers.

The lap splice lengths of deformed steel reinforcing bars and GFRP bars with two different to surface type were experimentally compared using beam specimens. The purpose was to evaluate the length required of the GFRP bar to develop strength equivalent to the conventional steel reinforcing bar. The main test variable was the lap splice length. Two different GFRP bar surfaces were tested: (1) spiral-type GFRP bars and (2) sand coated GFRP bars. For the conventional steel bars (SD400 grade), strength over 400 MPa in tension was reached using the lap splice length of $30d_b$. Splice failure was observed in the specimen with the lap splice length of $20d_b$. For the spiral-type and sand coated GFRP bars, the tensile strength developed in the GFRP bars decreased with decreasing splice lengths. Development of the cracks on beam surfaces was clearly visible for the beams reinforced with the GFRP bars. Mid-span deflections, however, were significantly smaller than the comparable beams with conventional steel bars indicating potential ductility problem.

RC frames built prior to the advent of the philosophy of ductile concrete is one type of existing construction susceptible to damage. Strengthening and stiffening of such frames has been accomplished by infilled frames with cast-in-place, reinforced concrete walls. Placement of CIP shear walls within strategic bays of a structure appears to be a logical and economical method to strengthen a reinforced concrete frame and to stiffen a building in order to reduce architectural and mechanical damage. This study investigates the seismic performance of cast-in place infilled shear wall within existing frames. The object of this study is to clarify the seismic capacity and characteristics in the hysteretic behavior of bare frame, CIP infilled shear wall and CIP infilled wall reinforced diagonal bars.

This study is an experimental study to investigate the shear behavior of reinforced concrete shear walls with openings and to determine the shear strength of those walls. This paper compares rigidities of walls with opening by different opening types. The experimental results, as expected, show that the crack load, yield load, and limited load are inferior for specimen with larger opening area. The magnitude of axial stress and shear stress had a significant effect on the deformability of shear walls with opening.

External prestressing method is the most papular method to strengthen concrete structures. The key parts of external prestressing method is an anchoring device which holds the prestressing cables. The most popular anchoring devices is an end bearing type, which has to be welded at site to assamble the anchor. The welding at site has a significant Quality problem. In this paper, new anchoring system has been developed, which needs no site welding. A design method for the new anchor has been proposed and developed to optimize the anchoring system. The developed anchors are very efficient, small, and compact, which have two types, one for abutment section and the other one for pier section. The anchors are expected to be used very widely, because of its convinience.

The first thing in remodelling of an apartment is the enlargement of living area, which is usually attained through extending balcony or corridor to the outside of the building. As a reasonable solution to the extension of floor a method of rigid connection in which steel bars are injected into the existing slab and concrete of newly building slab is installed with proper reinforcement is proposed in this research. To verify the structural performance of the method bending tests have been carried out for seven slab specimens.

This paper presents test results to prevent debonding failure of reinforced concrete beams strengthened with near-surface mounted(NSM) CFRP. Beams strengthened with different strengthening systems with externally bonded CFRP, NSM CFRP and NSM CFRP with mechanical interlocking. Test results indicated that using NSM CFRP is improved the stiffness and increased the flexural capacity of RC beams and NSM CFRP with mechanical interlocking prevented debonding failure of RC beams.

Carbon Fiber Reinforced Polymer(CFRP) composites are widely applied to strengthen deteriorated concrete structures. This paper presents the experimental results of the performance of reinforced concrete(RC) beams strengthened with Near Surface Mounted T-shape CFRP. Simple beams with 3m span length were tested to investigate the effect of CFRP reinforcement shapes on the flexural behavior of strengthened RC beams. The test results were analyzed with the special emphasis on the failure mode and the maximum load.

This paper present test result to develop wedge-type anchor system for external prestressing method with CFRP. The test results indicated that the lower a slope angle and elastic of wedge are, the higher ultimate strengths are for plate types. Bar types showed premature failure because of local high stress in FRP of anchor system. Therefore, to improve the strength for bar types needs further work of strengthening sleeves, slope angles of wedge and materials.

This study was performed to analyze effect of cyclic load during CFS curing on the behavior of RC beam strengthened with CFS. In the experiment, five different beginning times of cyclic load and two different strengthening amounts of CFS were chosen for experiment parameters. From the experimental results, it could be known that the cyclic load during CFS curing might give detrimental effects to the CFS strengthening effects compared to without cyclic load cases.

Steel encased composite columns have been used for buildings and piers of bridges. Since column section for pier is relatively larger than that of building columns, economical steel ratio need to be investigated for the required performance. Composite action between concrete and embedded steel sections can be obtained by bonding and friction. However, the behavior. of the column depends on the load introduction mechanism. Compression can be applied to concrete section, steel section and composite section. In this paper, experiments on shear strength of the steel encased composite column were performed to study the effect of confinement by transverse reinforcements, mechanical interlock by holes, and shear connectors. Shear strength obtained from the tests showed considerably higher than the design value. Confinement, mechanical interlock and stud connectors increased the shear strength and these values can be used effectively to obtain composite action of SRC columns.

Compressive strength of self-compacting concrete with waste concrete powder(SCCWCP) linearly decreased as the containing ratio of WCP increas. When granulated blast furnace slag(SG) was contained for improving the rheological properties of SCCWCP, compressive strength of concrete with $15\%$ SG and $15\%$ WCP was increased in comparison with that of concrete with $30\%$ WCP. Splitting tensile strength of SCCWCP higher increased than that of CEB-FIP at same compressive strength. Relationship between compressive strength and elastic modulus of SCCWCP indicated a similar function with CEB-FIP fuction.

The change of creep deformation mechanism due to the persistent change of stress conditions requires the constitutive relation for the analysis of long tenn behaviors considering age dependent material properties of concrete. In the present research, the process of time dependent behaviors in structure is divided into two stages; the non-mechanical deforming level which causes creep and shrinkage deformations, and the mechanical deforming level which causes mechanical deformations by the restraints of non-mechanical deformations due to internal or external factors. The incremental constitutive relation is derived by expanding the total stress-strain relation on the present time, with respect to the reference time using the Taylor series, and the modulus of elasticity in early ages of concrete was defined thru this process.

Recently, the use of structure compound waterproof agent (hereinafter referred to as 'SCWA') that is used when manufacturing concrete for concrete structures, increases in quantity. However, while it is expected that the SCWA that is mixed in the concrete inside can significantly affect the change of physical properties that lift the internal force of a structure. This study has been conducted through an experiment for the effects of cement hardener on the formation of microscopic texture, and newly generated hydrates from that result were not confirmed in the present experiment. It was found that at the hydrate reaction it has the property that can be hardened within the limit of pore diameterar a specific size rather than there is the internal gap filling capacity due to generating other hydrates.

This paper proposes degree of hydration based shrinkage prediction model of 40MPa HPC. This model shows degree of hydration which is defined as the ratio between the hydrated cement mass and the initial mass of cement is very closely related to shrinkage deformation. In this study, degree of hydration was determined by CEMHYD-3D program of NIST. Verification of the predicted degree of hydration is performed by comparison between test results of compressive strength and estimated one by CEMHYD-3D. Proposed model is determined by statistical nonlinear analysis using the program Origin of Origin Lab. Co. To get coefficients of the model, drying shrinkage tests of four specimen series were followed with basic material tests. Testes were performed in constant temperature /humidity chamber, with difference moisture curing ages to know initial curing time effect. Verification with another specimen, collected construction field of FCM bridge, was given in the same condition as pre-tested specimens. Finally, all test results were compared to propose degree of hydration based model and other code models; AASHTO, ACI, CEB-FIP, JSCE, etc.

This paper investigated the setting and compressive strength of concrete with the combination of mineral and chemical admixture. According to test results, plain concrete with high early strength development type AE water reducing agent(HEAEWRA) and $10\%$ of CKD respectively had earlier setting time than concrete with AE water reducing agent by $0.5\~1.5$ hours. Setting time of concrete with retarding type AE water reducing agent(RAEWRA) and FA $30\%$, BS $60\%$ respectively retarded by as much as $4\~7.5$ hours compared with plain concrete. Plain concrete with HEA WRA, $10\%$ of CKD and RAEWRA had higher strength than that of AE water reducing agent by as much as 5MPa at 28days. From the result of the paper, it is found that the combination of mineral admixture and setting accelerating or retarding agent can reduce the hydration heat cracks by setting time difference and hydration heat reduction effects.

This research is targeting that estimate the effect on cement concrete pavement with type of chloride deicers. In order to this study objective, when chloride deicers were spread on road surface, thermal characteristics test was conducted. Also, skid resistance test according to types and concentration of chloride deicier, road surface conditions were investigated. As a test results, thermal characteristics with kind of chloride deicier could know that sodium chloride(NaCl) is exothermic reactive material, calcium chloride$(CaCl_2)$ is endothermic reactive material. And, in case of mixed salt of the calcium and sodium chloride, it could know that can change to the exothermic or endothermic reaction according to dosage ratios. Skid value by British Pendulum Tester(BPT) has shown that it is seldom difference between the types($CaCl_2$, NaCl, mixed salt) and solution concentrations(0.5, 0.8, 1.0, 4.0, $10\%$) of chloride deicier comparing with tap water except mixed salt($10\%$ solution concentration).

The purpose of this study is to investigate properties of porous concrete according to volume of binder and compaction energy. The result of this study, as compaction energy goes on increasing, the actual measured void ratio is decreased according as a change of compaction energy and volume of binder. The compaction energy has a very near value by target void ratio on the whole when it is $50kN{\cdot}m/m^2,\;50\~75kN{\cdot}m/m^2$ in case of target void ratio is $15\%\;and\;25\%$. As compaction energy goes on increasing, compressive strength of specimens picked up when target void ratio is $20\%\;and\;25\%$. Also, compressive strength of specimens bluntly picked up when compaction energy is over $50\~75kN{\cdot}m/m^2$.

Concrete Filled steel Tube pipe structure is a rational type of structure that maximizes performance by combining the strong points of steel frame and concrete. In the structure, the confining effect of steel pipes increases the bearing power of infilled concrete and the strengthening of local bucking of steel pipes by infilled concrete increases the bearing power of members. and these result in the reduction of cross-sectional area and high transformation capacity. Moreover. the structure is economically efficient and widely applicable that it is used from super-high buildings to residential, business and apartment buildings. It enables the construction of multi-story buildings with long spans using columns of small cross-sectional area. In case of diaphragm, however, it is difficult to confirm the compactness of the closed inside of steel pipes. The present study examined the properties of super-high strength concrete over 80MPa by comparing it with 40MPa concrete through heat conductivity and length change tests based on a mixture ratio satisfying the mixture goal presented in the guideline for the design and construction of concrete-filled steel pipe structure. and evaluated the performance of super-high strength concrete according to the shape and size of the aperture ratio of diaphragm.

The Purpose of this study is to develope the method for early recovery of the biodiversity in the oligotrophical costal area, it is important in the recovery of the biodiversity to make kelp forest grow in the concerned area. In order for it, sufficient nutrient is required as well as the proper seedbed, Hence in this study, granulated fertilizer, which contains nutrient, such as nitrogen, phosphorus and etc, is coated by cement paste, and then is mixed in to the porous concrete in order to provide seedbed and nutrient simultaneously. The physical and mechanical properties, such as water permeability, void ratio, compressive strength of porous concrete with granulated fertilizer are discussed.

The annual consumption of coal by coal-fired power plants is increasing. Also a large amount of ash is produced. The disposal of this large amount of ash makes the serious environmental problems and economical loss. Fly ash among the ash produced is used in building industries as a substitute to cement in concrete. But bottom ash is not used because of its poor properties. This study is aimed at the production of foamed concrete using bottom ash, to examine the physical properties of foamed concrete is manufactured by autoc1aving, and to exhibit the fundamental data to use it in site.

As the purpose of this study is a research of series to obtain fundamental data on the development of the product of foamed concrete using bottom ash for various applications in the field, the main purpose is the light weight of product of concrete. In this experiment, method of mixing of foam is very important because it control specific gravity and strength of the product. As the test results, it was found that regardless of mixing method the grower the concentration of foaming agent the lower the specific gravity and the compressive strength of the specimen especially pre-foaming method. From a strength point of view, we knew that mix-foaming method and steam curing is efficient to obtain a adequate compressive strength of foamed concrete.

This study aims to manufacture and to evaluate lightweight cement composite using lightweight aggregate and expanded perlite. The expanded perlite and lightweight aggregates were mixed with cement, water, SP(superplasticizer), forming-agent and poly-propylene fiber. The specimens were cured at $20^{\circ}C$ for 24h and then at steam curing of $60^{\circ}C$, RH $100\%$ for 12h. As a result, We could make lightweight cement composite of satisfaction about ALC properties. However it is need to improve the properties of density and water absorption.

Recently, for industrial development period, concrete structures in domestics have been increased. They were deteriorated by attack of carbonation, freeze-thaw and corrosion etc. In hence they were demolished and reconstructed, resulted in waste concrete particles. In this paper, waste concrete particles (WCP) by product from different crushing and selecting process were used in soil cement-based pavement in the various recycling. For using WCP in soil cement-based pavement, the Qualities, physical and chemical properties, of WCP should be researched. In the first step, the specified compressive strength of mortar for two types of clay sand soil and clay soil respectively was experimented to be 15 Mpa and then optimum mixing ratio of chemical solidification agent were decided in the range of $1.5\~3.0\%$ in the replacement with cement weight content. In the second step, based on the prior experimental results, recycling possibility of WCP in soil cement-based pavement was studied. In the result of experiment the mixing ratio of WCP were 5, 10, 15 and $20\%$ in the replacement with soil weight and the compressive strength of mortar was somewhat decreased according to the increase of the mixing ratio of WCP.

The purpose of this study is to examine the antibiotic and physical properties of antibiotic concrete added inorganic liquor-type antibiotic agent(as named for Antibio-C) as the basic data for the development of antibiotic concrete. The main experimental variables were the types of antibiotic agents and it is tested for the properties of antibiotic, flow, compressive strength, crack-resistance and durability of concrete. As results, concrete containing antibiotic agent presented the strong antibiotic activities compared with non-added concrete. Also antibiotic concrete showed the higher or equality properties than non-added concrete with respect to compressive strength, crack resistance and durability such as neutralization depth.

This paper is to investigate the shrinkage properties of high performance concrete (HPC) with mixture adjustment by using mock-up specimens. HPC with mixture adjustment needed a higher dosage of SP agent due to fluidity reduction and a larger dosage of AE agent due to the reduction of air content. Setting time of HPC with mixture adjustment exhibited earlier than that of control HPC by as much as 6 hours. HPC with mixture adjustment gained more than 70MPa of compressive strength. Autogenous shrinkage of Control HPC was found to be $-340\times40^{-6}$ at 49days when the expansion value by thermal effect was excluded and HPC with mixture adjustment $-175\times10^{-6}$, which was the half of the value of control HPC. Drying shrinkage of center section of HPC with mixture adjustment showed similar tendency with autogenous shrinkage because of no internal moisture movement, while surface section had larger drying shrinkage. The specimen embedded with reinforcing bar had smaller deformation caused by confinement of reinforcing bar.

This paper investigated the drying and autogenous shrinkage of high performance concrete(HPC) with mixture adjustment under various specimen size. For fresh concrete properties, HPC with mixture adjustment need a higher dosage of SP agent due to fluidity reduction, and a larger dosage of AE agent due to the reduction of air content. HPC with mixture adjustment exhibited a smaller strength development than control HPC. For drying shrinkage, an increase in specimen size occurred with small expansion during water curing and at air curing, less drying shrinkage was observed. Autogenous shrinkage was not affected by specimen size. Autogenous shrinkage of HPC with mixture adjustment exhibited less than half of control HPC.

This paper is to investigate the spalling and fire endurance of high performance RC column member with PP fiber and lateral confinement of metal lath and non fire resistance removal type form. According to test results, combination of PP fiber and metal lath as well as use fire resistance non removal type form had favorable fire resistance by discharging internal vapour pressure and lateral confining. After fire endurance test, compressive strength decreased markedly caused by internal expansion pressure and crack. Residual strength of plain concrete was decreased to $22\%$. The use of PP fiber and lateral confinement of metal lath and non removal type form enhanced the residual strength above $40\%$. Especially, the combination of $0.1\%$ of PP fiber and lateral confinement with the level of 2.3T exhibited more than $51\%$ of residual strength. Therefore, to improve fire endurance and spalling resistance, the combination of $0.1\%$ of PP fiber and metal lath with 2.3T can be the proper measure.

This paper is to investigate the fire endurance of high performance concrete with the contents of cellulose fiber. According to test results, the use of CL lead to decrease in fluidity. For compressive strength, the use of CL had no influence on compressive strength. For spalling properties, plain concrete showed a severe spalling failure. The use of CL protected from spalling of concrete, but most specimens had scale failure and partial destruction of specimens. This is due to the insufficient fiber length and diameter of CL fiber, which was unable to discharging the internal vapour pressure. For this reason, CL fiber can not be used to protect from spalling oh high performance concrete. Residual strength was observed to $5\~7\%$ of original strength.

In this study, the properties of autogenous shrinkage and dry shrinkage for high performance concrete using Type I and Type IV cement were discussed. According to experimental results, autogenous shrinkage of SN30(the high performance concrete using type I cement) shows values higher than SL30( the high performance concrete using type IV cement). But the dry shrinkage of SN30 is almost the same as SL30. It is observed that the total shrinkage strain of SN30 is higher than that of SL30, because the ratio of autogenous shrinkage of the total shrinkage is relatively large. Therefore, SL30 is more effective to control or minimize the cracking of the high performance concrete, compared with SN30.

Properties examination of concrete using blast-furnace slag instead of cement is necessary, so it is planed that: basic data for utilization and performance management of blast-furnace slag by means of cement replacement is presented with experimental comparison and investigation of engineering properties of concrete according to the replacement ratio and fineness of blast-furnace slag.

This study was performed to investigate evaluation of workability from the application in construction site for watertightness concrete used in anti-crack agent. This study compares plain concrete test with field test was carried out at mat foundation(thickness a.8m) of newly constructed apartments of Noen Dong. Conducted tests show that the anti-crack agent was effective to progress compressive strength and control the crack and durability in a construction field.

High performance SFRC composed of mira-sized ultra fine particles is characterized by high strength, high ductility and excellent durability. therefore many researches about materials based on new composition like this are performed recently. many researchers have reported that adding steel fiber to concrete improved its tensile and flexural strength significantly. the main objective of this research is to examine the effect of adding steel fiber on the tensile strength of high performance SFRC. variables considered in this study are w/c ratio and fiber volume fraction.

Recently, DFRCCs (Ductile Fiber Reinforced Cementitious Composites), materials with remarkable ductility when compared to ordinary fiber-reinforced concrete (FRC), have been developed and studied actively in the US, Japan, and many European countries. The transformation of failure behavior from brittle to ductile is achieved by incorporating with fracture mechanics concept especially micro-mechanical models approach of cementitious composite materials in manufacturing ordinary fiber-reinforced composites. The purpose of this study is to accurately understand the shear behavior of DFRCC repaired RC beams. Using a four-point bending test, the shear strengths and shear stress-deflection relations of DFRCC repaired RC specimens are obtained. The results show that DFRCC can be effectively used for repairing materials for concrete structures.

High ductile fiber reinforced mortar suitable for wet-mix shotcreting (sprayable ductile mortar) 10 the fresh state, while maintaining tensile strain-hardening behavior in the hardened state, has been developed based on micromechanics and workability control. In the development concept of sprayable ductile mortar, micromechanics is adopted to properly select the matrix, fiber, and interface properties to exhibit strain hardening and multiple cracking behaviors in the composites. Within the pre-determined micromechanical constraints, the workability is controlled by optimizing mix proportions. A series of spray tests show the excellent pumpability and sprayability of the sprayable ductile mortar. Subsequent direct tensile tests demonstrate that the tensile performance of sprayed mortar is comparable to that of cast mortar, for the same mix design.

An analytical method is proposed for the analysis of the reinforced concrete flexural beam subjected to high temperature. The analysis procedure for the material properties, in this study, is subdivided into two types; thermal properties for temperature distribution analysis and mechanical properties for structural analysis. Using F.D.M. and segmentation method, the program was made to predict the thermal behavior of RC beams during heating. In previous studies, the structural behavior of fire damaged RC beams was investigated though experiments. Comparing the result by program to the one by experiment, the comparison indicated that the proposed segmentation method for the thermal respose analysis present fairly a good agreement with experiment.

Recently, a tendency for development of seismic approach of foreign countries is capacity design development. Capacity design is rational seismic design concept of capacity protection considering not only earthquake magnitude, but also behavior of structure. For that reason, the most bridge seismic design specifications contain capacity protection provisions explicitly or implicitly. The capacity protection is normally related with slenderness effect of the columns, force transfer in connections between columns and adjacent elements, and shear design of columns. It intends to prevent brittle failure of the structural components of bridges, so that the whole bridge system may show ductile behavior and failure during earthquake events. The objectives of this paper are to deduce needed provisions for the moderate seismicity regions such as Korea after studying current seismic design codes and to establish rational criteria provisions of seismic design for future revision of seismic design specifications.

In this study, the roughness of fracture surfaces in cementitious material has been characterized by roughness number (RN). A systematic experimental investigation was carried out to examine the dependency of fracture parameters on the aggregate sizes as well as the loading rates. Three aggregate sizes (0.1875 in, 0.5 in, and 0.75 in) and two loading rates (slow and fast loading rate) were used. A total of 52 compression tests and 53 tension tests were performed. All fracture parameters exhibited an increase, to varying degrees, when aggregates were added to the mortar matrix. The fracture surfaces of the specimens were digitized and analyzed. Fracture roughness was monotonically increased as maximum aggregate sizes increase.

The paper analyzes a scheme of decontamination of radionuclides from concrete structures, in which rapid microwave heating is used to spall off a thin contaminated surface layer. The analysis is split in two parts: (1) The hygrothermal part of the problem, which consists in calculating the evolution of the temperature and pore pressure fields, and (2) the fracturing part, which consists in predicting the stresses, deformations and fracturing. The rate of the distributed source of heat due to microwaves in concrete is calculated on the basis of the standing wave normally incident to the concrete wall with averaging over both the time period and the wavelength because of the very short time period of microwaves compared to the period of temperature waves and the heterogeneity of concrete. The reinforcing bars parallel to the surface arc treated as a smeared steel layer. The microplane model M4 is used as the constitutive model for nonlinear deformation and distributed fracturing of concrete. The aim of this study is to determine the required microwave power and predict whether and when the contaminated surface layer of concrete spalls off. The effects of wall thickness, reinforcing bars, microwave frequencies and power are studied numerically. As a byproduct of this analysis, the mechanism of spalling of rapidly heated concrete is clarified.

An economic analysis is one of the most dominant factors to determine the project feasibility of super tall building. In economic considerations, it is very important toadopt optimum structural floor systems because these are dependent on both the cost and the duration of construction. The economics affected by structural floor systems are more distinct athigher story. As the story increases, the construction cost of floor system. is accumulated linearly, while the cost of lateral resisting system is increased geometrically. The purpose of this study is to investigate the economical effects of super tall buildings through application of optimum structural floor systems. Three types of structural systems(RC beam-column frame, RC flat plate frame, and Steel frame) of super tall buildings having 50-stories are considered in this study and compared to RC flat plate slab with other systems. Analytical result shows that RC flat plate slab using lightweight concrete ismost effective in both the cost and the duration of construction.

The primary role of fibers in High performance fiber reinforced cement composites(HPFRCCs) is to improve the toughness, or energy absorption capacity, of the composite material, However, there is still no general agreement as to how this toughness should be characterized, or how it might be used in the design of structures containing HPFRCCs. In this paper, therefore, we focus on test techniques for measuring flexural toughness. For mechanical properties, HPFRCCs can be tested in the same way as fiber reinforced concrete(FRC). Both the significance and the limitations of somewhat different national and industrial standards of FRC are discussed. For flexural toughness, with depend on the presence of fibers, new test methods was developed and verified. We also suggest evaluation method of tensile toughness indices using the moment curvature relationship in flexural tests.

In this study, a moment resisting precast concrete beam-column connection is proposed. An experimental study was carried out to investigate the connection behavior subjected to cyclic loading. Three precast beam-column interior connections and one monolithic connection were tested. Variable included the detailing used at the joint to achieve structural constructability and the location of mild steel reinforcement and high strength bar. During specimen fabrication, the joint details enables ease and speed of construction. Connection performance is evaluated on the basis of ductility, energy dissipation capacity, connection strength, and drift capacity. Based on test results, the precast concrete beam-column connection is capable of matching or exceeding the performance of the monolithic connection.

The purpose of this paper is to study the effect of longitudinal reinforcement for anchoring in the wide beam column joint as wall as the contribution of depth of spandrel beam to hysteretic behavior of the wide beam column joint. From the test it was shown that the specimen with anchorage in the joint had higher strength than the specimen with normal hook anchorage. Specimen with debonded reinforcement at out of Id from column face failed showing moved plastic hinge and less strength than normal specimen. However, the dissipated energy was increased $11\%$.

This paper investigates a study on the bending behavior of beam strengthened with CFS under repeated loading. The test specimen consisted of 20cm in width, 40cm in depth, and 15cm in CFS width. We find the strength decrease under repeated loading test comparing with the monotonic incremental loading test.

An experimental investigation on the strength and behaviour of reinforced concrete columns using high performance fiber reinforced cement composites has been carried out. The columns were subjected to monotonic axial compression until failure. The variables in this study are the combination ratio of steel cord(SCI) and polypropylene(PP), and the volumetric ratio of transverse reinforcement Test results showed that the fibers, when used in a hybrid form, could result in superior composite performance compared to their individual fiber reinforced cement composites.

External bonding of steel plates has been used to strengthen deficient reinforced-concrete structures since the 1960s. In recent years, fiber-reinforcde polymer(FRP) plates have been increasingly used to replace steel plates due to their superior properties. This paper is concerned with anchorage failure due to crack propagation parallel to the boned plated near or along the adhesive/concrete interface, staring from the critically stressed position toward the anchored end of the plates. Factor of bond-slip interface model is average bond stress, effective length, slip volume and fracture energy. The aim of the present paper is to provide a comprehensive assessment of bond-slip interface model with concrete and CFRP plates.

Lately outmoded and functionally obsolete buildings are often remodelled and restored. When existing reinforced concrete(RC) apartments are remodelled, one of main reasons of the remodelling is to expand dwelling space. The experimental or theoretical research on plane expansion of RC apartments is quite scare. In this research, 9 RC slabs connected by hinged joints were tested. The test results indicated that the shear strength of the RC test slabs having various types of dowel bars was about twice that calculated by the ACI 318-02 code.

The posttensioning system of nuclear containment have to be verified its structural integrity by the periodic inspection because the structural behavior of the containment is changed by the variation of the physical property of concrete and tendon as time passes. In this study a program 'SAPONC-CANDU' which is able to monitor and analysis the micro structural behavior of the domestic CANDU type containment at all times was developed. The readings of vibrating-wire strain gauges embedded into the concrete of containment were used as input data for operating the program. This program provides the long-term prediction values and bands of the concrete strain due to the time dependent factors of the concrete and tendon of the domestic CANDU type containment.

This paper deals with the damage assessment of the concrete beam using Damage-area concept and the modulus of elasticity reduction of the beam was evaluated. Simply supported concrete beams were loaded at the mid-span. When the displacements from the tests were increased more than $10\%$ of the initial values, flexural cracks occured. Judging from the observed cracks, damaged area of the beams were assumed and the modulus of elasticity reduction using the smeared-cracking concept was estimated to minimize the error between the test results and analytical results. Main parameters for the assessment were height of the crack area, length of the crack area, position of the crack area and the modulus of elastic reduction ratio. In each stage, damaged elements and their stiffness reduction were estimated to minimized the error.

In the research for giving self-diagnosing capability, conductive mortar intermixed with cokes and milled carbon fiber was produced. Then after examining change in the value of electric resistance dsand AE characteristics before and after the occurrence of cracks at each weight-stage, the correlations of each factors were analyzed.

This study was performed to verify the possibility of the integrity estimation of the bridge substructure focusing on the dynamic property change of concrete pier with penetration depths using experimental modal analysis. As a result of the impact vibration test, it is found that scour reduces the stiffness of the foundation, and measurement the accelerance residue and natural frequency can be used for the estimation of the integrity index.

An analysis of the AF is performed for each bridge pier exposed to ship collision. From this analysis, the impact lateral resistance can be determined for each pier. The bridge pier impact resistance is selected using a probability-based analysis procedure in which the predicted AF, from the ship collision risk assessment is compared to an acceptance criterion. In this study, the acceptance criterion is allocated to each pier using allocation weights based on the previous predictions. To determine the design impact lateral resistance of bridge components such pylon and pier, the numerical analysis is performed iteratively with the analysis variable of impact resistance ratio of pylon to pier. The design impact lateral resistance can vary greatly among the components of the same bridge, depending upon the waterway geometry, available water depth, bridge geometry, and vessel traffic characteristics.

An analysis of the annual frequency of collapse(AF) is performed for each bridge pier exposed to ship collision. AF is computed for each bridge component and vessel classification. The summation of AFs computed over all of the vessel classification intervals for a specific component should equal the annual frequency of collapse of the component. The designer should use judgment in developing a distribution of the vessel frequency data based on discrete groupings or categories of vessel size by DWT. In the present study the effect of vessel classification on the annual frequency of collapse in the ship collision risk assessment is investigated by illustrative numerical examples based on the vessel frequency data of the domestic harbor. The DWT interval for larger vessels has more effect on the ship collision risk. Therefore the expert judgement in determining the larger DWT interval is required because the design impact lateral resistances of bridge components depend on the ship collision risk.

This study describes a practical method of measurement of the sustained stress in concrete structures. In most cases, the sustained stress was determined by various theoretical calculations. However, the theoretical calculations can not always provide sufficient informations about current stress state having lots of uncertainty. Therefore, the present study proposes a practical measuring method, Partial Sectioning Method.

In this study a program 'SAPONC-FRANCE' which is able to evaluate and analysis the elastic behavior property of the domestic FRANCE type containment under pressurization and depressurization in periodic structural integrity test (SIT) was developed. The readings of EAU system that is composed of the pendulum, invar-wire, leveling-pot, bench-mark, thermocouples and acoustic strain gauges were used as input data for operating the program. This program provides the prediction lines and bands of the pressure-strain(or displacement) relationship of concrete due to the changing of inner volume under pressurization and depressurization in SIT of the domestic FRANCE type containment.

The importance of predicting concrete compressive strength of in concrete structures is gradually increasing in construction industry. The estimation of concrete compressive strength of is a critical factor of the construction schedule and quality control. This study was performed to examine the relationship between concrete compressive strength and stress wave velocity which was determined by the impact echo method and SASW method.

Air void systems in hardened concrete has an important influence on concrete durability such as freeze-thaw resistance, water permeability, surface scaling resistance. Linear traverse method and point count method described at ASTM is the routine analysis of the air void system that have been widely used to estimate the spacing factor in hardened concrete. Recently, many concretes often have a spacing factor higher than the generally accepted $200-250{\mu}m$ limit for the usual range of air contents. This study is proposed to estimate the matrix spacing factor by calculation of simplicity. The matrix spacing factor needs two parameters that are air content and numbers of air voids in the hardened concrete. Those are obtained from the standard air-void system analysis of the ASTM C 457. The equation is valid for all values of paste-to-air ratio because the estimation of paste content is unnecessary at the using ASTM C 457. The matrix spacing factor yields a similar estimate of the standard spacing factor.

In recent years, some attention was particularly given to cracking sensitivity of high performance concrete. It has been argued and demonstrated experimentally that such concrete undergoes autogenous shrinkage due to self-desiccation at early age, and, as a result, internal tensile stress may develop, leading to micro cracking and macro cracking. One possible method to reduce cracking due to autogenous shrinkage is the addition of expansive additive. Tests conducted by many researches have shown the beneficial effects of addition of expansive additive for reducing the risk of shrinkage-introduced cracking. However, the research on hydration model of expansion additive has been hardly researched up to now. This paper presents a study of the hydration model of Ettringite-Gypsum type expansive additive. Result of comparing forecast values with experiment value, proposed model is shown to expressible of hydration of expansive additive.

The discharge of sewage sludge ash that is rapidly increasing in Korea. The utilization of sewage sludge ash would contribute to the elimination of an environmental problem and to the development of new high-performance materials. So the paper is focused on an experimental study in order to investigate the utilization of sewage sludge ash as the construction materials. It achieves leaching test, chemical composition and compressive strength test. As a result of tests, the sewage sludge ash has sufficient potential for use of pozzolanic raw material. However. it is judged to be available to construction material if research is continuously gone.

The effects of polymer-cement ratio and antifoamer content on the setting time and durability of high-fluidity polymer-modified mortars using redispersible polymer powder are examined. As a result, the setting time of the polymer-modified mortars using redispersible polymer powder tend to delayed with increasing polymer-cement ratio, regardless of the antifoamer content. The water absorption and chloride ion penetration depth of the high-fluidity polymer-modified mortars using redispersible polymer powder decrease with increasing polymer-cement ratio and antifoamer content. The water absorption and chloride ion penetration improvement is attributed to the improved bond between cement hydrates and aggregates because of the incorporation of redispersible polymer powder.

Recently, the usage of polymer concrete mortar gathering an interest as a new construction material rapidly increases inside and outside of the country because it is an environment-friendly and endurable material. However, up to these days, the researches about the polymer composite have not been satisfactorily conducted. The polymer concrete is superior to the general cement materials in the properties of strength and durability while it is inferior in elastic modulus. Because that the members using the polymer concrete have therefore higher strength and ductility than the members of general cement concrete, an analysis equation of high-strength cement concrete can be referenced but it is not applied for the researches about the polymer concrete members. In this study, the flexural properties of T-shaped beam of the steel- and GFRP-reinforced polymer concrete are analyzed to examine the suggested analysis equation. Results of this experimental researches are to be used as the basic data in a structural design of the polymer concrete.

Plastic shrindage cracking occurs at the exposed surfaces of freshly placed concrete due to consoilidation of the concrete mass and rapid evaporation of water from the surface. This so called shrindage craking is a major concern for concrete, especially for been performed to obtain the plastic shrindage porperties of cellolus fiber reinforced concrete. The results of tests of the cellolus fiber were compared with plain and polypropylene fibers. Test results indicated that cellolus fiber reinforcement showed an aility to reduce the total crack area and maximum crack width significantly.

This study is basic experiment for estimating influence of strength by curing temperature of concrete's heat of hydration and estimate relationship of compressive strength development by initial curing temperature factor, and then asume temperature factor which influence compressive strength development and for showing basic document of quality control. According to the result of cement mortar by the curing temperature factor high-curing temperature shows high strength on 3 day compare with low curing-temperature, shows higher strength than the piece of high curing temperature.

This paper reported the results of mock-up test on mass concrete for transfer girder using setting time difference of super retarding agent(SRA). According to test results, two mock-up structures were made. Plain concrete without placing layer reached maximum temperature after 24hours since placement and caused surface hydration cracks at top section. However, concrete with placing layer reached maximum temperature after 72hours and surface temperature was higher than center temperature, which did not cause surface crack. After form removing, no crack was observed at side surface of plain concrete, while concrete using SRA at mid section had surface scaling and settling crack. According to coring results, concrete with placing layer had a penetration crack from top section to bottom section. Therefore, the setting time difference method to reduce hydration heat will have difficulty in applying the mass concrete for transfer girder.

The setting and hardening of concrete is accompanied with nonlinear temperature distribution caused by development of hydration heat of cement. In order to predict the exact temperature history in concrete structures it is required to examine thermal properties of concrete. In this study, the coefficient of air convection, which presents thermal transfer between surface of concrete and air, was experimentally investigated with variables such as velocity of wind, boiling and layer effects. Finally, the prediction model for equivalent coefficient of air convection was theoretically proposed. The coefficient of air convection in the proposed model increases with velocity of wind, and its dependance on wind velocity is varied with types of form. For determining the initial coefficient of air convection, boiling effects must be considered. The coefficient of air convection is affected by boundary layer with respect to the distance from the surface.

The evaluation of durability of resin concrete was examined through various tests, i.e., compressive strength, absorption, abrasion, chemical attack resistance and bond between general and resin concrete. 2 types of concrete were used such as 40 MPa of general concrete and 90 MPa of resin concrete. The characteristics of resin concrete was more improved than that of general concrete, and especially, resin concrete was most effective on compressive strength, the resistance to $H_2SO_4$ solution attack and absorption. However, abrasion. is almost same between general concrete and resin concrete.

Resins using recycled PET offer the possibility of a lower source cost of materials for making useful polymer concrete products. The purposed of this paper is to form a part of reducing the damage of sulfuric acid, through investigating recycled PET polymer concrete, . immersed at sulfuric acid solution for 84 days. Recycled PET PC is excellent chemical resistance, resulting in the role of unsaturated polyester resin which consists of polymer chain structure accomplishes bond of aggregates and filler strongly. Also, Recycled PET PC, used fly-ash as filler, is stronger resistance of sulfuric acid corrosion than $CaCO_3$, because it is composed of $SiO_2$ and very strong glassy crystal structure. Therefore, Recycled PET PC, used fly-ash as filler, is available under corrosion circumstances like sewer pipe or waste disposal plant.

Porous polymer concrete can be applied to roads, sidewalks, river embankment, drain pipes, conduits, retaining walls, yards, parking lots, plazas, interlocking blocks, etc. This study is to examine a content ratio of polypropylene fiber to improve bending strength, impact resistance and freezing and thawing rssistance of porous polymer concrete. Also, this study is performed to develop the porous polymer concrete using recycled coarse aggregate and blast furnace slag for application of structures needed permeability. At 7 days of curing, compressive strength, flexural strength, water permeability and flexural load are in the ragge of $17\~21MPa,\;5\~7MPa,\;4.1\times10^{-2}\~7.7\times10^{-2}cm/s$, respectively. It is concluded that the recycled aggregate can be used in the porous polymer concretes.

The purpose of this study is to evaluate the fundamental properties of fine type cement grouts with redispersible polymer powders. Cement grouts with redispersible polymer powders are prepared with various polymer-cement ratios, and tested. for flow, water absorption, drying shrinkage, flexural and compressive strengths. From the test results, flow of the cement grouts with EVA and Va/VeoVa polymer powers decreased with increasing elapsed time. Regardless of polymer type, the flexural strength of the cement grouts tends to increase with increase in polymer-cement ratio. The maximum compressive strengths of the cement grouts are obtained at a polymer-cement ratio of $5\%$.

Admixture compounds for reducing setting time and accelerating early strength development of redispersible polymer powder-modified mortars were made by mixing various inorganic accelerating inorganic materials. Redispersible polymer powder-modified mortars are prepared with various accelerator contents, and it was tested for setting time, flexural and compressive strengths. As a result, the accelerators contribute to strength development of the mortars in the early curing age of 12h or less. In the viewpoint of early strength development of redispersible polymer powder-modified mortars, an accelerator content of $20\%$ is recommended.

In this study, it was founded to make the optimal mixture for producing concrete which is self-compacting, yet, and generates low heat of hydration by using fly ash, blast furnace slags and limestone powders as binders in addition to cement while using super-plasticizers and viscosity agents as admixture agents. The structural behaviors of the concrete produced with the selected mixture were compared with those of the concrete currently using for construction of nuclear power plants. The study shows that the blended high fluidity concrete including limestone is better in workability and durability than the concrete currently in use for nuclear power plants.

In this study, it was founded to make the optimal mixture for producing concrete which is self-compacting, yet, and generates low heat of hydration by using flyash, blast furnace slags and limestone powders as binders in addition to cement while using super-plasticizers and viscosity agents as admixture agents. The structural behaviors of the concrete produced with the selected mixture were compared with those of the concrete currently using for construction of nuclear power plants. The study shows that the blended high fluidity concrete including limestone is better in workability and durability than the concrete currently in use for nuclear power plants.

This research investigates experimentally an effect on the properties of the high flowing concrete according to variations of concrete materials and site conditions. Variations of sensitivity test are selected items as followings; (1)Concrete temperature, (2)Unit water(Surface moisture of fine aggregate), (3)Fineness modulus of fine aggregate, (4)Addition ratio of high-range water reducing agent. And fresh conditions of the high flowing concrete should be satisfied with required range including slump flow$(65{\pm}5cm)$, 50cm reaching time of slump flow$(4\~10sec)$, V-box flowing time$(10\~20sec)$, U-box height(min.300mm) and air content$(4{\pm}1\%)$. As results of sensitivity test, material variations and site conditions should be satisfied with the range as followings; (1)Concrete temperature is $10\~20^{\circ}C$ (below $30^{\circ}C$), (2)Surface moisture of fine aggregate is within ${\pm}0.6\%$, (3)Fineness modulus of fine aggregate is $2.6{\pm}0.2$ and (4)addition ratio of high range water reducing agent is within $1\%$ considered flow-ability, self-compaction and segregation resistance of the high flowing concrete.

Lightweight concrete is known for its advantage of reducing the self-weight of the structures, reducing the areas of sectional members as well as making the construction convenient. Thus the construction cost can be saved when applied. to . structures such as long-span bridge and high rise buildings. However, the lightweight concrete requires specific design mix method that is quite different from the typical concrete, since using the typical mix method would give rise the material segregation as well as lower the strength by the reduced weight of the aggregate. In order to avoid such problems, it is recommended to apply the design mix method of high performance self-compacting concrete for the lightweight concrete. Therefore, this study introduces a production of self-compacting concrete, PF-modified and improved version of Nan-Su's design mix method of self-compacting concrete. Through a series of test mixes conducted during the study, the quality of the concrete at its fresh condition has been evaluated per the 2nd class rating standards of self-compacting concrete published by JSCE, especially focused in its fluidity, segregation resistance ability, and filling ability.

There are many factors that affect on the flowing properties of high flowing concrete(HFC), which are fluidity, compactibility, non-segregation ability and fillingability. And because the aggregate which is one of the factors occupies high volume in concrete, it has a much effect on the properties of high flowing concrete according to its size, quality and quantity etc. This is an experimental study to analyze the effect of admixture and volume of coarse aggregate in concrete on the flowing properties of high flowing concrete. For this purpose, the kinds of admixture are fly-ash and blast furnace slag. Also volume of coarse aggregate in concrete are 280, 290, 300, 310, 320 $(\ell/m^3)$. The test of flowablity properties is slump-flow, Air content, V-lot, L-Flow. According to test results, it was found that the compactibility of HFC is more superior to use blast furnace slag than other, and according .to kind of admixture, most compatible volume of coarse are different. Also when used blast furnace slag, the volume of coarse are increased than used fly-ash.

Self-compactability is defined as a capability of concrete to be uniformly filled and compacted in every corners of formwork by its self-weight without vibration during placing. To evaluate the self compactability of self compacting concrete, the slump flow, the time of slump flow at 500mm and U-box apparatus testing methods are used. In this research, the fresh and hardened properties of self compacting concrete using ground granulated blast furnace slag as a part of cement were investigated for the volume contents of sand in the mortar. The workability, flowing characteristics, air content and compressive strength of concrete were tested and the results were compared with the different volume contents of sand in the mortar. In the experiment, we acquired satisfactory results at the point of flowing characteristics and strengths of self compacting concrete.

In this study, the experiment was carried out to investigate and analyze the ready-mixed concrete production of ultra-high strength concrete with mixing strength of $100N/mm^2$ according to types of mineral admixtures. The main experimental variables were water/binder ratio $25.0\%$, water content $160kg/m^3$ and mineral admixtures such as fly ash, silica fume and meta kaolin. According to the test results, the principle conclusions are summarized as follows. 1) even if it secures similar slump, the viscosity appear to difference by mixing condition relatively. 2) The autogeneous shrinkage of ultra-high strength concrete is profitable that use admixture, and heat of hydration is desirable that apply considering countermeasure enough in the advance. 3) The concrete that use SF10+MK10 on 56days could confirm that it is possible that achieve compressive strength more than $100N/mm^2$ under mixing conditions that is appearing by compressive strength $102.7N/mm^2$.

This study reports the site application of the early strength development technology for form stripping earlier than normal state in the apartment construction. It is a method of framework rationalization and it needs the technology of early strength development concrete and 6-day cycle process. We applied the method to the apartment construction to reduce the floor construction period and to maximize the economical effect by reduction of the period of total construction. As a result, we confirmed the superior property of the early strength development of the concrete and reliable success of 6-day cycle process.

Very-Early-Strength Latex-Modified Concrete(VESLMC) provides the repairing material with short curing time as well as excellent bond strength, flexural strength and impermeability against water and chloride. In 2001, VESLMC introduced in Korea and improved superior material through research and development on material properties and durability. In 2003, the field test progressed for study problems of VESLMC field application. This paper introduced equipment improvement for bridge deck repair save both repair time and labor, while producing quality VESLMC structures.

The so-called Life Cycle Cost (LCC) analysis on reinforced concrete bridge can provide useful information for initial design and maintenance plan of the RC bridge. This paper proposes an LCC prediction equation and a sensitivity analysis method for RC bridges. An LCC equation for the RC bridge which includes initial investment cost, maintenance cost, and demolition cost was derived and verified from the data for design and construction of an RC slab bridge. In order to solve uncertainty problem on actual discount rate and material characteristics in the analysis of LCC of concrete bridges, a sensitivity analysis method on the LCC using the Monte Carlo simulation technique was suggested.

Recently, the use of structure compound waterproof agent (hereinafter referred to as 'SCWA') that is used when manufacturing concrete for concrete structures, increases in quantity. However, while it is expected that the SCWA that is mixed in the concrete inside can significantly affect the change of physical properties that lift the internal force of a structure. This study has been conducted through an experiment for the effects of cement hardener on the formation of microscopic texture, and newly generated hydrates from that result were not confirmed in the. present experiment. It was found that at the hydrate reaction it has the property that can be hardened within the limit of pore diameterar a specific size rather than there is the internal gap filling capacity due to generating other hydrates.

Method of Steel plate reinforced by fiber sheet is advantageous in the secure loading facility. For this method are a light weight and a high strength, the thickness of steel can be reduced Effects of composite system are depreciated when the thickness of steel is thin. This is the result of the difference of ductility ratio with steel plate. Steel plate reinforced by fiber sheets confirms the ability of transformation. This is the result of the property of steel materials Steel plate reinforced by fiber sheet didn't display an enough performance when theadhesives are epoxy rosin. This is the result of the slide of the surface of stee1. The adhesive ability is varied by the number and span of anchor bolts. There wasn't happening the separation between steel and epoxy. Thus the method used in combination with anchor and epoxy is best excellent. This is the result of the upward of accumulation effects Shearing force is in proportion to the number of bolts. But the ability of shearing force per one bolt is reducing. Thickness of steel plate reinforced by fiber sheet must be designed so that steel is endure before concrete is wreck.

In order for concrete as a basic material constituting reinforced concrete structure to meet the required performance, it is necessary to satisfy various requirements in concrete construction. Among them, form work has significant effects not only on the process of molding fresh concrete but also on the quality and performance of hardened concrete. Recently, the decrease and aging of form workers is becoming a great problem in the construction industry and, as a result, it is required to rationalize form works and reduce labor costs for employing form workers.

This study aims to detect only voids and estimate the cross-sectional size and thickness of voids using radar. A new method based on radar image processing is carried out with various void sizes and depths. The regression relationship between void size which has different depth and the amplitude characteristics of the radar return is considered in a new method of this research. For the purpose of examining; this regression relationship, experiments with change of void depth, surface area and thickness were carried out. Finally, the threshold value for image processing which aims to represent only voids to be fitted size (width) can be obtained. As the results, a proposed method in this study has a possibility of detecting only voids and estimating void size and thickness with good accuracy.

In domestic, various repair materials and method systems to keep up with these reinforced concrete deteriorated due to salt damage, carbonation. chemical decay et. being developed and applied. However, present polymer cement mortar applied to section restoration system cause the problem of long-term working and economica] efficiency. because that is divided into two process of liquid corrosion prevention agent and polymer cement mortar. In this background, accelerated test with due regard to $3\%$ NaCl soaking and autoclave cure was performed to confirm steel bar corrosion prevention properties of polymer cement mortar mixed with corrosion prevention agent of powdered type. In conclusion. we confirmed application possibility and excellency of steel bar corrosion prevention properties of polymer cement mortar mixed with corrosion prevention agent of powdered type comparing general polymer cement mortar applied to section restoration system of present study.

Some test results indicated that the current ASTM grip adapter of GFRP rebar was not successful in developing the design tensile strength of GFRP rebar with reasonable accuracy. It is because the current ASTM grip adapter of GFRP rebar does not take into account the various geometric characteristics of GFRP rebar such as surface treatment, shape of bar cross section, bar deformation as well as physical characteristics such as poisson effect, elastic modulus in the transverse direction and so on. The research reported in this paper is to provide how to proportion an adequate grip adapter to develop design tensile properties of GFRP rebar. The proposed grip adapter is derived from the equilibrium or compatibility equations. From the preliminary test results for rounded GFRP rebar, it was found that the grip adapter with specific size proportioned by proposed method shows the highest tensile strength among them.

It should be noted that the critical chloride threshold level is not considered to be a unique value for all conditions. This value is dependent on concrete mixture proportions, cement type and constituents, presence of admixtures, environmental factors, steel reinforcement surface conditions, and other factors. In this study, the accelerated corrosion test for reinforcing steel was conducted by electrochemical and sea water-circulated method, respectively and during the test, corrosion monitoring by half cell potential method was carried out to estimate the critical chloride threshold value when corrosion for reinforcing steel in concrete was perceived. For this purpose, lollypop and beam test specimens were made for $31.4\%,\;41.5\%\;and\;49.7\%$ of w/c. respectively and then the accelerated corrosion test for reinforcing steel was executed. It was observed from the test that the time to initiation of corrosion was found to be different with water-cement ratio and the critical chloride threshold value was found to range from 0.91 to $1.27kg/m^3$.

In this study, several properties are improved when high efficient inorganic type agent and organic-inorganic type agent are applied. Especially high efficient inorganic type agent can improve the properties of concrete such as water-resisting capability more effect than organic-inorganic type agent applied.

The evaluation of characteristics of concrete coated by high performance surface penetration agency was examined through various tests, i.e., compressive strength, penetration depth, water and air permeability, absorption according to various high performance surface penetration agencies and various compressive strengths of base concrete. The 4 types of high performance surface penetration agencies were used i.e., organic, inorganic, water soluble, and alcohol soluble. And 3 types of compressive strength of base concrete were used such as 21, 24 and 30 MPa. The characteristics of concrete coated high performance surface penetration agency was more improved than that of non-coated concrete, and especially, water soluble inorganic agency was most effective. And if compressive strength of base concrete was low, the improved effects would be larger.

This study was performed to investigate bonding performance of epoxy resins for repairing of cracks in concrete, as a part of project to establish quality control standard for epoxy resins. In the slant shear strength test for hard and soft type epoxy, hard type was higher about 3 times than soft one. From the results, it is thought that hard type is suitable for load carrying. Injection of epoxy resin in the notch made flexural strength increase about $47\%$ over the specimen that epoxy resin is not injected. There were no differences in bonding performances with viscosity. Application of epoxy resin on the wet concrete surface made slant shear strength decrease about $46\%$, but similar performance to the case of application on the dry surface appeared by using epoxy resin for wet condition.

Our country was much developments in change of construction environment along with fast economy development. But, various problems that must think in problem of safety and quality were appeared. Constructions which build through rapid economy development are getting many social criticisms to problem of crack and water leakage at use process. Is situation that huge repair expense to cure this is engaged. Safety problem of construction is indicated socially through various media mediums again.

For nuclear concrete structures on the coast, the prevention and management against salt damage is needed because they are being under the influence of the sea water at all times. In general, the deterioration of the concrete is generated in concrete surface firstly and then extended into concrete gradually as its service life increases. Therefore, the protective layer on the concrete surface is needed to establish and manage the durability of concrete. To enhance the durability performance of the existing and new concrete, the development and application of a high-performance penetration sealer is needed. The sealer has to have the functions that are able to prevent the attack of the moisture, carbon dioxide, and harmful substance from the outside. Therefore, the aim of this study is to development of a sealer for the long service-life and waterproof performance of a nuclear concrete structures.

The objective of this study is to examine mechanical properties of ductile fiber-reinforced mortar designed based on micromechanics. This mortar was produced by employing raw materials commercially available in Korea. To verify property level of this material in uniaxial tension, a series of direct tensile tests were performed with varying water cement ratio. In addition to this, flexural tests as well as compressive tests were carried out. Experiments revealed that the fiber reinforced mortar exhibited high ductility represented by strain hardening behavior in uniaxial tension. Significant enhancements of ductility, in terms of strain at peak stress and post-peak behavior, were also observed during the tests in compression and in bending.

FREP(Fiber Reinforced Epoxy Panel), the products of our company, was widely made full use of a field of the reinforced concrete. In particular, the FREP used for repair and reinforcement of the subway and tunnel is required flame retardative property. In this study, flame retardative FREP using flame retardant of non-halogen system was fabricated by impregnation method. Flame retardative grade was the third grade. Tensile strength, flexural strength, and compressive strength was 1,384, 1,298, and $1,450kg/cm^2$, respectively.