In this paper, we decribed the basic elements required for the practical usage of super flowing concrete. The flowability and filingability of fresh concrete was measured by using six different testing methods. Also, two actual size members were used for investigating characteristics of the hardened concrete through variious experiments. As the result of the experimentation, the developed super flowing concrete shown high flowability and fillingability good enough for the requirement. Furthermore, inner uniformity of the no-vibrated concrete was verified by testing distribution of aggregates and core cylinders. Therefore, quality control and workability of concrete can be secured by using the super flowing concrete even without vibrating However, it ha been felt that development of easy evaluation methods for the super flowing concrete is in need.

High flowing concrete has been made using a combination of different cementitious material. The use of supplementary cementitious material like ground granulated slag is not only interesting from an economical point of view but also from a mechanical and rheological point of view. In the case of high strength concrete, relation between the maturity and compressive strength development of high strength concrete is aproximated by appling gompertz curve and suggested new estimating method. It is the aim of this study to analysis the effect of different types of mineral fine power on the setting and compressive strength development of high flowing concrete.

Since cement is one of materials of concrete and have an important effect upon physical properties of concrete, the quality characteristics of ordinary portland cement in domestic market are evaluated in this study. For this purpose, eight kinds of cement are selected and tested on the specific gravity, normal consistency, setting time, fincness, and compressive strength of cement ranged from 300kg/$\textrm{m}^3$ to 600kg/$\textrm{m}^3$ are tested for each kind of cement. As a result,ordinary portland cement in domestic market are satisfied with physical performance prescribed by KS L 5201(Portland Cement) and when unit weight of cement is 300~600kg/$\textrm{m}^3$, the maximum compressive strength of concrete cylinder is showed to be about 440-540kgf/$\textrm{cm}^2$.

Most difficulties in inducing high flowability of general strength concrete arise from the segregation of aggregates due to the shortage of cementatious binders. To solve the problem, our research team has concentrated on finding the binders to link a gap between coarse and fine aggregates, under the condition not to influence a concrete strength. As a result of using stone powder or a middle class of aggregate size mostly used for asphalt pavement(Max. dia 13mm), we found that flowability of concrete increased significantly without aggregation and decrease of compressive strength.

To perform high-strength of concrete, fine powers of pozzolan such as fly ash, silica fume mixed with cement. But mobility of cement and concrete decreased due to using of these powers. To control decrease of this mobility, it is required that mobility is improved by using of chemical admixture such as superplasticizer. We used admixtures -NSF, NM-2, NT-2 etc- in order to improve mobility of cement paste being substituted by 10, 20% of pozzolans respectively. It proved that optimum dosage of NSF, NT-2 was 2.0% for being substituted 10%, 3.0% for 20% so as to increase mobility of cement paste mixed paste mixed with fine powers of pozzolan at W/C=0.40.

There are carbonatiion, salt attack, freezing & thawing and alkali-aggregate reactions as the cautions of durability lowering of concret structure. Generally, these cautions complicatedly lower the durability of structure and among these cautions the most serious problem is salt attack and carbonation. This study is intending to get the carbonation phenominon, that among cement calcium hydroxides change into calcium carbonate by responding to carbon mitrogen in the air.

There are carbonatiion, salt attack, freezing & thawing and alkali-aggregate reactions as the cautions of durability lowering of concret structure. Generally, these cautions complicatedly lower the durability of structure and among these cautions the most serious problem is salt attack and carbonation. This study is intending to get the carbonation phenominon, that among cement calcium hydroxides change into calcium carbonate by responding to carbon mitrogen in the air.

The purpose of this study is analyze to the properties of high fluidity concrete(W/C 35~50%) with the dosage of viscosity agent(Hydroxy Propyl Methyl Cellulose ; HPMC ; 15U), From the resuls, flowability was good about 200g/㎥. segregation-resisibility and placeability were good upward 300g/㎥, To synthetic, the dosage of viscosity agent are discovered best in 200~400g/㎥

The fundamental properties of High Performance Concrete(HPC) were studied using high flowable portland cement which was developed at the Sangyong Cement Ind. Co.,Ltd. The results obtained are as follows. (1)The slump of HPC using high flowable portland cement maintains for 120min. (2)Ultra high strength greater than 800kg/$\textrm{cm}^2$ can be designed without using silica fume and other additives. (3)The value of drying shrinkage and adiabatic temperature rise of HPC are less than those of concrete made with OPC.

Recently, high-workable concrete has been developed and began to be used to a great extent in foreign countries, but it isn't familiar with and fully introduced in Korea yet. The aim of this paper is to suggest a reference data for the development of High-workable concrete according to the comparative analysis the effect of mix proportion (unit water sand/aggregate ratio) on the flowing characteristics. And also this paper aims to examine the compactability of High-workable concrete in a model wall-form.

In this study, the properties of super flowing cocrete containing gly ash were experimentally investigated and compared with those of ordinary concrete. Tests were carried out on five types of super flowing concrete mixes containing fly ash and three types of ordinary concrete mixes without fly ash. Flow test, O-funnel test, box test, Ltype thest and slump test were carried out to obtain the properties for the workability of fresh concrete. Compressime strength, splitting tensile strength, modulus of elasticity. creep and shrinkage test were also obtained as the mechanical properties of hardened concrete. In fresh concrete, it was found that super flowing concrete had excellent workability and flowability compared with ordinary concrete, and the volume ratio of coarse aggregate to concrete volume greatly influenced flowability. Super flowing concrete also had good mechanical properties at both early and late ages with compressive strengths reaching as high as 40 MPa at 28 days. The creep deformation of super flowing concrete investigated were relatively lower than that of ordinary concrete.

The aims of this study is to test silica sand abundantly buried over the country as a concrete admisture material, and investigate its utility as a replacement for the favored nature resource to prevent the economic loss.

The primary purpose of this study is to investigate reusal techniques of fly ash of combined heat power plant in the construction field, which may contribute to the saving of construction materials and conservating environment. Firstly chemical and physical characteristics of fly ash is analysed. And then, the usability of the concrete is tested by investigating the flowablility and stength development through parameters of various replacement ratios with respect to different mixing conditions. Finally, the durability and mechanical properties(elastic modulus) of the concrete is tested. As the result of the study, the following conclusions are derived : (1) the quantity of the CaO in the fly ash is relatively high based on the chemical analysis, (2)the compressive strength ratio of the mortar is satisfied with the specification, but the unit water ratio increased, (3)high strength concrete of more than 400kg/$\textrm{cm}^2$ can be developed in the ranges of FA 30%, W/B 40%, (5)the slump loss with the elapsed time due to the delivery is decreased as the replacement ratio of the fly ash is increased, (6)the modulus of the elasticity is matched withn the specification of the Architectural Institute of Korea.

The results of an experimental study on the manufacture and the mechanical properties of fiber reinforced calcium silicates-cement composites utilizing by products (fly ash or cement sludge) for construction materials are presented in this paper. As the test results show, compressive, tensile, and flexural strength, fracture toughness of fiber reinforced calcium silicates-cement composites were improved by increasing the fly ash and fiber contents, but were decreased by increasing cement sludge contents. Somehat, especially increasing fiber contents the fracture toughness of the composites were remarkably increased. Also, the mechanical properties of the composites reinforcing alkali-resistance GF were higher than those of the composites reinforcing Samoa Pulp.

In order to develope and apply high-performance steel fiber reinforced concrete (SFRC), the effects of steel fibers on durability and long-term deformation of SFRC due to various mixing conditions have been studied. As the test result show, the manufacturing process technology of industrial SFRC is developed And the durability of SFRC such as freeze-thaw, resisteance abrasion resistance are significantly improved, the drying shrinkage of SFRC, is remarkably decreased by increasing the steel fiber contents than plain concrete

The results of an experimental study on manufacture and mechanical properties of concrete utilizing crushed sand and fly ash for construction materials are presented in theis paper. As the results show, the workability, compressive strength and freezing-thaw resistance were improved by proper contents of fly ash, replaced crushed sand, and air entraining agent. And the drying shinkage was decreased by proper contents of those. Also, the suitable weight contents of replacing ratio of crushed sand and weight ratio fly ash in concrete using crushed sand were in range of 30% and 15% respectively.

For the development of lilght weight cement concrete with high durability, this study used perlite and paper sludge ash by the light weight material, and polypropylene fiber by the reinforcment, and poly-acrylic ester emulsion by the matrix improvement. According to the increasing mixture ratio of fiber and use of polymer, the light weight polypropylene fiber reinforced polymer cement ratio of fiber and use of polymer, the light weight polypropylene fiber reinforced polymer cement concrete were showed high resistance for frost damage.

In this study the characteristics of adiabatic and lightweight of cement mortar was improved by using porous Bottom ash which was industrial waste. when a foaming agent was added, the characteristics of mortar using sand and Bottom ash were compared. From the empirical results the heat-transfer ratio for the mortar using Bottom ash only was shown the lower values than that for a general mortar, and the lightweight concrete with unit weight of 1.5t/$\textrm{m}^3$ could be made. When the foaming agent of 0.25% and 0.5% in usage of cement was added to that, the compressive strength scould be measured as 5 and 8times of the general mortar respectively. Also, the characteristics of adiabatic for that mortar was great improved so that the heat-transfer ratio was fallen to 0.172kcal/$mh^{\circ}C$.

The intention of this study is to reduce the drying shrinkage of the cement mortar using the shrinkage reducing agent and the inorganic admixture. In this experiment the drying shrinkage strain, rate of weight loss and strength have been measured depending on age using the motar specimen. The result show that the usage of shrinkage reducing agent up to 1.5% will give an effect of approximately 30% without loss of strength, and the efficiency will increase together with the inorganic admixture. Also, as the amount of shrinkage reducing agent increases, the rate of weight loss increases. Drying shrinkage reduces at the same rate of weight loss.

In this study, the fundamental properties of nonshrinkage high strength concrete using calcium sulphoaluminate cement (CSA cement) which was develiped at the Ssangyong Cement Ind, CO., Ltd. Were considered by some experiments. The concrete using CSA cement show a good workability and higher strength development in early age. And, the resultant compressive strength was also higher than OPC. The drying shrinkage of CSA concrete was much less than that of concrete made with OPC and expansive agent.In addition, the value of drying shrinkage was not dependent on the agitating time and the curing condition. Compared to that of OPC.

The purpose of this study is to suggest concrete mix proportioning design using Blast-furnace slag cement. The mix conditions are specified by concrete strength(180~400kg/$\textrm{cm}^2$), slump$(15\pm2cm)$m and air volume$(4.5\pm1%)$. From the result of concrete mix proportioning design using Blast-furnace slag cement, unit water content can be reduced by 3~8% comparing with OPC. The relationship between strength at 28days and cement water ratio is as follow. when blast-furnace slag cement is used: $\sigma_{28}$=304.OC/W-296.8. Super-plasticizer have to be used to get a slump of 15cm when water/cement ratio is less than 45%.

This paper presents an accelerated-curing method by the war water method and discusses how these methods can be adapted for regular quality control and quality assurance of concret. Accelerated strength test data can be used for estimating the furture stength, e.g. the 28-day strength. An accelerated-curing method to predict the 28-day strength of concrete from 1-day warm water-cured test results was evaluated in the laboratory and the field. For these evaluations test are performed for 1845 standard specimens from 123 different batches of concrete. The results of this study the equation applicable universally with resonable accuracy are presented for estimating the potential strength of concrete by the warm water-curing method.

It is the "maturity rule" that concrete of the same mix, at the same maturity, has the same strength. In this study, the Nurse-Saul function which was proposed to account for the effects of temperature and time on strength development is used in computing maturity. After existing various functions to relate concrete strength to the maturity value are considered, new strenth-maturity function is proposed. Tests are conducted in order to compare prediction value with measured concrete strength. The constants in proposed prediction equation are determined by standard specimens(cylinders) test, and the equation is adopted to predict strength of slab. The slab was cast in the laboratory from the same batch of mole, and cores are cut from slab in order to estimate the actual strength. Tehese values are used to compare with proposed equation. equation.

The purpose of this study is to evaluate the flexural bond performance in beam using 3-types anti-corrosion coatings. For the test. we used $15\times\times20\times110cm$ R.C beams, in which the epoxy, the red lead, and the cementitious anti-corrosion coating re-bars used. The results of test using these 3-type anti-corrosion coatings are shown that the flexural bond performance of cementitious anti-corrosion coating rebar in R.C beam is superior to other anti-corrosion coatings rebars.

The reinforced concrcte structure were once belicved to have permanent durability. However, it is now spoiled by durability failure caused by the corrosion of embeded steel reingorcement carbonation. alkali-aggregate reaction and salt attack Recently. salt damage has been also spreading. Salt damage is found in concrete structures built using seasands or certain admixtures containing calcium chlorides and in coastal structures frequently caught in seawater spray or blown by seawind It is the aim of this study to investigate the performance and application of new repair system for the exterior wall according to the durability improvement in the RC structures.

It is the aim of this study to introduce the performance and application of new repair system for the exterior wall by durability failure caused seasand especially. The elementary performance of this repair system is as follows (1)All the layer in the repair are cement based, same with the mother conrete (2)this repair system use SBR admixture (3)This cement and mortar powder for this repair system are premixed and ready to use just adding admixture at the job site.

This study is to recognize the effect of silica-fume, fly-ash, and chemical proportion in mortar that have salt on the inside affect steel bar corrosion. water-binder ratio, 0.5, compounds, each of 10, 15, 20% by weight of cement, Nacl mixing weight, 0.5, 1.0, 2.0% by weight of binder, The speciment is sealed and cured for 28days, the corrosion area ratio and weight reduction ratio is measured after the accelerated corrosion test of 20 cycles. The conclusion shows that there is no suppression effect of steel bar corrosion of silica-fume, fly-ash, in case of having salt on the inside.

The purpose of this study is to evalute the mechanical and the anti-corrosion characteristics of cementitious, organic coatings on steel plates. Tests are performed according to KS M 5331, 5250, etc'. For the test, we used water based epoxy, Tar epoxy, the red lead, and cementitious anti-corrosion coatings. The results of adhension tests satisfying the requirements in relevant standards The impact test shown that the impact test shown that the impact resistance of cementitious anti-corrosion test, rred lead, epoxy, cementitiouse show good corrosion resistance.

High durabitiy concrete increasingly sutudied in various countries. This report presents the data on durability related properties such as the chloride ion permeability, the resistance to freezing-thawing, the corrosion of steel and the resistance attack. To promote the actual application of high durability concrete, several series of high durability concrete have been made and applied to actual structures.

The purpose of this experimental research is to not only devlop the high-strength concrete using sea and river sand, but also investigatc mechanical properites of the high-strength concrete, such as the elastic modulus, the compressive strength of concrete cyllinder, and etc. Also, rational analytical formula for elastic modulus has been proposed together with those for the splitting tensile strength and the flexural strength to be predicted from compressive strength of conccrete cyllinder.

As nation's infrastructure is getting old, nondestructive evaluation of existing structures and construction quality control are getting important. In this paper non-destructive evaluations of concrete members using impact echo and SASW methods are introduced. Both techniques are based on the stress wave propagations. Experimental tests were performed using beam type concrete member where voids and cracks are included. Within reasonable accuracy, void locations were detected using impact echo method and the dynamic modulus of concrete were measured using SASW method. Both NDT methods showed a feasibility for the implementation into quality evaluaton of concrete members in practice

Establishment of a diagnosing technology for the deterioration of reinforced concrete structures due to salt contamination is urgent, but few analytical methods based on measured data obtained from concrete structures have been presented so far. Chloride penetration into concrete from sea water is generally understood and analysed as diffusion of chloride ion. This paper presents a new method of predicting chloride penetration into concrete based on diffusion theory. Also, it determines the duralility of Marine structure in service with the prediction of remaiing lifetime by the carvonation test.

Thermal cracks ard occured when thermal stress due to the hydration of cement exceeds the tensile strength of concrete. Since cracking causes poor durability of concrete, the effect of thermal cracking should be included for the desing and construction of massive concrete structures. In this study, an experiments are performed for the investigation of time dependent temperature and thermal stress of massive concrete structure at early ages. In order to measure temperatures and thermal stresses, concrete stress meter, embedded strain meter, non-stress meter, and thermocouples are used. Based on the analyses of measured thermal stress data, measured values by concrete stress meter are more reliable than those by embedded strain meter and non-stress meter, And measured values by concrete stress meter are compared with the calculated values by FEM program developed by DICT (DWTS2D). Calculated values by DWTS2D show good agreement with measured values.

Strain localization is important phenomenon since it governs the total behavior or ultimate loads in various kinds of engineering problems. Establishment of an analysis method for strain localization phenomena is also of great concern for expansion of fracture mechanics of concrete. Inside zone of localization, a decrese in stress is accompanied by an increse in strain; outside the strain decreses. All deformation localization phenomenon cannot be predicted by both the classical stress-strain formulation and the linear elastic fracture mechanics. In this paper, a simple one dimensional model including localized deformation zone is studied under compressive and tensile loading. When the model is loaded. localization is assumed to occur uniformly in a finite region and material outside the localization zone is modelled as elastic unloading occurs. Size effects of effective elastic moduli under compression and tension in localization zone are examined.

Most defects in the cement concrete pavement take place mainly on the joints. These corner cracks don't happen as often as others relatively. it happens continuously. In order to analyze the structural behavior of the corner cracks, The finite element structural analysis was performed on the representative section of the cement concrete pavements using JSLAB which uses FEM analysis method. On plain cement concrete pavements, The result shows that loading not only on the joints but also on the center of slab brings out the maximum stress on the corner of slab and it is expected to make the corner cracks.

Four types of experiments were performed to check the similitude of member behavior between prototype and 1/10 scale models:(1) Test of slender columns with P- effect, (2)Test of short columns with and without confinement steel, (3)Test of simple beams without stirrups, and (4)T-beam test. Based on the results of experiments, the conclusions were made as follows : (1) The P- effect of slender columns can be almost exactly represented by 1/10 acale model. (2)The effect of confinement on short columns by the hoop steel can also roughly simulated by 1/10 scale model. (3)The failure modes of simple beams models were the yielding of tension steel followed by large diagonal tension cracking+compressive concrete failure. (4)The behaviors of prototype and 1/10 scale model in T-beams appear very similar.

Computer-based methods have often been used in the structural analysis. But, regardless of the progress in the technique of structural analysis, there are inevitable limitations in consideration of the material and eometric nonlinearity and prediction of failure loads. Model analysis of concrete structure can supplement this kind of limitations to reasonably predict behavior of the structure. Similitude requirement in the reinforced concrete structure is often hard to be secured because of peculiar uncertainty of concrete. In this study, small scale model of subway box structure was constructed using strength model and results of model of subway box structure was constructed using strength model and results of model test and computer-based analysis were compared.

The objective of this study is to provide the information on the techniques of manufacturing and experiment in small scale modeling of precast concrete(P.C.)large panel structures. The adopted scale was 1/5th 4types of experiments were performed : material tests for model concrete and model reinforcement, compressive test of horizontal joint, shear test of vertical joint and cyclic static test of 2-story subassemblage structure. Based on the experimental results, the following conclusions are drawn: (1)Model concrete may have in general larger compressive strength than expected. (2) Model reinforcement can show less ductility if the annealing processes were performed without using vaccuum tube. (3) Failure modes of horizontal and vertical joints were almost same for both prototype and model. But the strength of model appears to be higher than required by similitude law. (4)Hysteretic behavior of 1/5 scale subassemblage model can be made quite similar to prototype's if the ductility of model reinforcement and compressive strength of model concrete could be representative of those of prototype.

The influence of the interfacial properties on the bond capacity of reinforcing bars to concrete is studied in this paper. In this study, the deterioration of the interfacial bond capacity when top-cast bars or epoxy-coated bars are used is examined. The effect of such variables on bond capacity in reinforced concrete is studied by experiment which use beam-end specimens. The main objective of this study is that comparing the test results and the requirements in ACI 318-89 code. the verification of the factor in ACI code is also presented in this paper. The results of the test show that "top bar effect" is considerably affected by the slump of fresh concrete, so the influence of slump shoud be taken into account for top bar effect factor in code. Test results also shows that the bond-slip curve of the epoxy-caoted bars is similiar to that of the uncoated and bond strength is reduced about 15% and that coating thickness seems to influence the bond strength deterioration.rioration.

Research on concrete-filled steel columns has been conducted. It is also well known that the load and deformation capacity of concrete-filled steel columns are considerable larger than those of widely used reinforced concrete columns and steel encased concrete columns because the concrete core in the steel is confined laterally by the steel. But, most of these works focused on columns with strength enhancement by the confinement effect, so that no local buckling prevented by the concrete. columns because the concrete core in the steel is confined laterally by the steel. But, most of these works focused on columns with strength enhancement by the confinement effect, so that no local buckling prevented by the concrete. This paper, therefore, presents on the stress-strain relation of a concrete filled rectangular steel tube under axial compression. As the results, the axial load verse average axial strain relationship of concrete-filled rectangular steel columns were very stable. The small B/t ratios in concrete-filled rectangular steel columns aren't affected prevention of local buckling but strength enhancement by confinement effect.

This paper presents an experimental study on the strength and deformation of concrete-filled circular steel short columns. Six specimens of concrete-filled circular short columns were tested under concentric compressive load. For comparsion, three specimens of circular steel short columns were also loaded to failure. The ultimate strength, ductility, and confinement mechanism of columns were compared. In the comparison, the effect of witch-thickness ratio and concrete compressive strength on the behavior of colimns were examed. As a result, the axial load verse axial average strain relationship of concrete-filled circular steel columns was very stable, because of interactions between the concrete and steel, the strength are 13% and 30% larger than the strength extimated by simply superimposed method of the concrete and steel. The ratio of the circumferential to longitudinal strain increment, both measured on the steel suface, was 0.28 up to the longitudinal strain of 0.1%, increases from 0.3 to 0.8 between the strain of 0.1% to 0.3%, and 0.8 beyond the strain of 0.3%

Since the mid of 1970's, the construction of infrastructure has been booming and accelerating to keep up with rapid economic growth. Fast achievement of most construction activities has caused unfavorable effects of civil petitions associated with damages and nuisances due to last hasty works. it is well known that the falling down of Sungsoo bridge and the collapse of Sampoong department and other structures have occurred because of the construction not conforming with the specification, and thereby incurred enormous loss of life and property. Now a days. a periodic inspection and maintenance have been strongly interested on aged RC structures, of repair and reinforcement technique in the country, most repairing and reinforcing works have been performed on the basis of the guidance of few experienced local company in this field.

Addition of hooked steel fibers into the cementitious materials enhanced shear resistance and consequently improves structural behavior and shear strength of reinforced hooked steel fibrous concrete beam(RHSFCB) under the shear forces. Experimental observations were made on the main parameters effecting structural behavior of RHSFCB in this study. The volume fractions of fibers, shear span to depth ratios, and spacings of stirrups were taken into account as the main parameters. Some equations reported in the literatures, regarding the predictions of the shear strength of RHSFCB have been evaluated statistically based on the total number of 95 test results on RHSFCB failed in shear on shear-flexural mode.

In this study we have the properties of drying shrinkage crack of hardened cement mortar using admixtures. The drying shrinkage cracking test process has been examined by the restrained drying shrinkage strain by restraining rate measuring properties of strain-with- restraint by JIS original proposal and keeps a flow value of mortar about 100$\pm$5%. The results show that the usage of shrinkage reducing agent 1.5% was effective on the control of drying shrinkage in OPC and CP by restraining rate 20% and strain-with-restraing 20~30 $\mu$, the usage of expansion agent 0.45% was effective by restraining rate 50~60% and strain-with-restraint 40~80$\mu$, and the effectiveness was increased with shrinkage reducing agent. Also. admixtures such as Flyash, CP and NC reduced restrained shrinkage and drying shrinkage cracking and more with shrinkage reducing agent

A 36 stories high multi-use building was designed with the specified concrete strength range of 300~400kg/$\textrm{cm}^2$ On the ground of the concept of compressive strength, adequate mix designing for the concrete, which has the target strength range of 390-520kg/$\textrm{cm}^2$, was carried out to provide enough strength margin. And with due regard to the workability and transportation time, the slump and slump flow ranged 16~21cm and 30~45cm respectively, maintaining these properties up to 2-hours from the beginning of the mix. The high-range water reducer is incorporated into the mix as a admixture. The building construction is controlled satisfactorily, so far. The actual average 28-day compressive strength is 370kg/$\textrm{cm}^2$, the standard deviation is 28kg/$\textrm{cm}^2$ and the coefficient of variation is 7.6% for concrete of 300kg/$\textrm{cm}^2$ specified strength.

This study is for estimating strength of mass concrete by finding out temperature and strength distribution through manufacturing actual model of construction mixed by appropriate mixing ratio, which is selected by result of exciting study and expriment of test-piece. Following result was obtained from experiment of member model to find out strength revelation of high mass concrete.

To reduce the size of structural members high strength concrete has recently been utilized for structrue such as ultra-high-rise buildings and prestressed concrete bridges in North America. and its compressive strength has gone up to 1300kgf/$\textrm{cm}^2$. In Japan, research on high-strength concrete has been undertaken on a large scale by the national enterprise so-called New RC Project, and this project purposed to develop the design compressive sstength of 1200kgf/$\textrm{cm}^2$. Considering these circumstance. the aim of this aim of this experimental study is to develop ultra-high-strength concrete with compressive stength over 2300kgf/$\textrm{cm}^2$ with domestic current materials. There are so many factors which influence on manufacturing of ultrahigh-strength concrete. The experimental factors selected in this study are mixing methods, curing methods, water-binder ratio, maximum size of coarse aggregate, and the replacement proportion of cement by silica fume. The results of this expermental study show that it is possible to develop the ultra-high-strength concrete with compressive strength over 2300kgf/$\textrm{cm}^2$.

To reduce the size of structural members, high strength concrete has recently been utilized for structure such as ultra-high-rise buildings and prestressed concrete bridges in North America. And its compressive strength has gone up to 1300kgf/$\textrm{cm}^2$. In Japan. research on high-strength concrete has been undertaken on a large scale by the national enterprise so-called New RC Project, and this Project purposed to develop the design compressive strength of 1200kgf/$\textrm{cm}^2$. Considering these circumstance. the aim of this experimental study is to develop ultra-high-strength concrete with compressive strenght over 2300kgf/$\textrm{cm}^2$ with domestic current materials. There are so many factors which influence the manufacturing of ultra-high-strength concrete. The experimental factors selected in this study are mixing methods. curing methods. water-binder ratio, maximum size of coarse aggregate, and the replacement proportion of cement by silica fume. The results of this expermental study show that it is possible to develop the ultra-high-stength concrete with compressive strength over 2300kgf/$\textrm{cm}^2$.

Large-scaling recycling of demolished concrete will concrete will contribute not only to the solution of a growing waste disposal problem, it will also help to consweve natural resoures of sand and gravel and to secure future supply of reasonly priced aggregates for building and other construction purposes within large urban areas. Because recycled aggregate particles consits of substantial amount of relatively soft cement paste component, it is less resistant to mechanical actions. With this view in mind, to obtain a reference data for the development of recycling system and to a basic data the guiedline of recycled aggregate concrete construction and engineering properties of recycled aggregate concrete according to the factors, such as blending ratio of recyced aggregete with the natural aggregate, addition to the factors, such as blending ratio of recycled aggregete with the natural aggregate, addition of flyash, water coment ratio.

This paper present the application and construction characteristics of Ultra-High Strength Concrete on Samsung Sin Dae-Bang Housing-Commercial Combined building with 28 story including 8 story basement in seoul. 1200kg/ $\textrm{cm}^2$compressive strength has been placed for paraphet at lst floor for experimental purposes. 420kg/$\textrm{cm}^2$ design strength concrete was used for other basement and frame up to 10th floor which is used for commercial purposes.

The objective of this study is to investigate the effect of concrete strength on the stirrup effectiveness factor(K) of reinforced concrete beams with stirrup based on previous test results(a/d$\geq$2.5). In the procedure of the estimation of K, it was assumed that the ultimate shear strength for beams without stirrup is equal to the concrete contribution to shear strength for beam with stirrup. A model equation for calculation the stirrup of compressive strength of concrete. It was shown that the stirrup effective factor of compressive strength of concrete. It wah shown that the stirrup effective factor is greater than 1.0 up to compressive strength 85MPa. Therefore the current ACI Code equation for predicting the shear strength and the stirrup effectiveness factor of 1.0 is conservative for nomal and high stength concrete beams with stirrup.

This study presents the physical and adhesive properties of the top coated materials for concrete slab. i.e, cement based top coated materials. epoxy mortar. The purpose of this study offers the investigation of construction factors to affect the quality of the coated materials over hardened concrete. The experimental results shows that the water content 3% of sand decline the strength and adhesive properties of epoxy mortar, on the other hand, dry surface and curing for cement based material.

In this study, the influence of the lateral pressure on the interface shear transfer of concrete has been investigated experimentally. A total of 21 specimens has been tested at the laboratory. The lateral pressure intensities in the tests have been taken as 0, 7, 14, 28, and 35kg/$\textrm{cm}^2$ for the specimens, the compressive strengths of which are either 180, 400 or 550kg/$\textrm{cm}^2$. The linear regression analysis based on the test results has shown relatively good agreements with the values given in the shear friction theory.

This paper is on experimental study on the behavior of reinforced concrete columns subjected to longitudinal steel ratio To investigate the effects of concrete strength and longitedinal steel ratio on the behavior of reinforced concrete columns. a series of tests were carried out for thirty-six tied reinforced concrete columns with a 100mm square cross section and three slendemess ratio of 15, 30 and 50. And To study and illustrate the change of the ultimate loads and that of displacements, two different concrete strength of 180,26kfg/$\textrm{cm}^2$, 819,36kfg/$\textrm{cm}^2$ and five different longitudinal steel ratio of 0.5, 1.0, 4.0, 5.7 and 10.3% were used. The boundary conditions at the ends were both hinged and the end eccentricities (17mm) were equal and of the same sign. While the ultimate load capacity of high-strength concrete column was much increased when the columns were short, that was not when the columns were slender. The effect of longitudinal steel ratio on the increased of ultimate load of column was more evident for slender columns than for short ones and the ultimate of longitudinal steel ratio were more pronounced with increasing concrete strength. The more inserted the longitudinal steel, the more increased the ultimate load, but the superabundance of longitudinal steel ratio over the limitation of maximum steel ratio in ACI code was used, it was showed that the ultimate load was rather decreased.

This study experimentally evaluate the bonding performance of repair and strengthening materials. It is very important problem to justify bonding properties between repair and strengthening materials and old concrete. Many previous research and investigation showed that bonding strength of reinforcing materials determines the strengthening effect and the durability of repair work. Therefore, menifestation of bonding properties and the improvement of bonding performance of repair and strengthening materials are very important. In order to improve the perforamnce of repair work, it needs to investigate the behavior of bonding materials, such as stress distribution along the bonding area and the long term performance of the material. The target repair methods are steel plate addition technique and repair mortar method, and the test parameters studied in this paper include epoxy thickness, bonding surface texture, and bonding area.

In this study the influcence of the lateral pressure on bond behavior of reinforcing barshas been investigaed experimentally. A total of 36 specimens has been tested at the laboratory. The tests have been carried out for the uniaxial and biaxial pressures of the intensities of 0, 5, 10, 20 and 40kg/$\textrm{cm}^2$. the compressive strengths of the specimens are either 360 or 520 kg/$\textrm{cm}^2$, and two kinds of bars, round and deformed, have been used. Based on the test results, linear regression equations have been proposed, and the comparisons between test results and the regression calculations have been made.

Flat-plate buildings are commonly modeled as two-dimensional frames to calculate lateral drift, unbalanced moments, and shear at slab-column connections. For gravity loads. the slab-column frames are analyzed using equivalent column approach, while equivalent beam approach is typical for lateral loads. The equivalent beam approach is convenient for computer analysis, but no rational procedure exists for determining the effective width of foor slabs. At present, the determination of the equivalent slab width and its stiffness is a matter of engineering judgement. To account for cracking, overly conservative assumptions are made regarding the stiffness of the slab. A rational approach is therefore needed to realistically estimate the equivalent slab width and its stiffness for unbalanced moment and lateral drift calculations. Based on the test results of 8 interior slab-column connections, an equivalent beam model is proposed in which columns are modeled conventionally as a function of column and slab aspect ratios and the magnitude of the gravity load. the proposed approach is verified with selected experimental results and is founded to be practical and convenient for analyzing flat-plate buildings subjected to gravity and lateral loading.

This study is to examine the usefulness in using precast girder-infilled steel tube column in reinforced concrete structures through the analysis of the test results, in order to develope the new composite structural system using precast girder-Infilled steel tube column, The variables of specimen are strength of concrete, the numble of hoops, the form of beam-column The variables of specimen are strength of concrete, the number of hoops, the form of beam-column joints. By raising strength of concrete and incresing number of hoops in beam-column joint, it becomes clear to take similar structure capacity to monolithic structures.

This paper is experimental study to define the structural behaviors of reinforced flat plate under combined gravity and lateral loads. Specific objectives of this study reported herein are : (1) To study the behavior of a typical slab-column subassemblage under lateral loading. (2) To study the effects of vertical loads on slab-column lateral load behavior. (3) To investigate the post-failure behavior of slab-column connetios. To achieve these objectives, this study includes four tests of slab-column subassemblages that were made for 1/2 scale. Finally, Test results of this study show that the level of gravity load on the flat plate is one of the most important factors determining the lateral behavior of flat plate connections.

The usual methods for the temperature control of mass-concrete structures include the use of low-heat cement, pre-cooling, or pipe-cooling. In order to control the heat of hydration of mass-concrete structures such as massive pier or anchor block, and mat foundation, the pipe cooling method is widely acceptable for pratical use. In this paper, method of analysis using the Finite Element Method was applied to analyze the heat exchange on the field of three dimensional thermal conduction. The result of analysis Well agreed with experimentally measurement data by "KUMATANI". The method of this analysis will be used widely to control the heat of hydration by the pipe cooling in mass-concrete.-concrete.

In recent years, the prediction of the deterioration rate of concrete structures has become major research interest. However, there are still many uncertain factors in the deterioration process and the relation between deterioration and durability of structures. This is mainly due to various uncertainties involved in the construction process and the environmental conditions which affect the rate of deterioration of concrete structures. In this study a limit state model in terms of random crack width due to applied dead and live loads is proposed for the assessment of crack damage of reinforced concrete structures. The AFOSM reliability method is used for the reliability evaluation of the crack durability of concrete bridges. The proposed model for crack durability of concrete bridges is applied to the Seoul interior circuit elevated expressway. The sensitivity analyses are performed for the proposed model.

In assessing the performance of structures such as bridges. the load intensity, load effect analysis and strength parameters are not known with certainty. The aim of structural reliability theory is to account for the uncertainties in evaluating the strength of structural systems or in the calibration of safety factors in structural design codes. The intend of structural reliability theory is to characterize these uncertainties and allow for consistent and rational safety decisions. In this study the rational model considering the live load applied to bridge will be introduced. using the structural reliability theory.

In recent years, the most common bridges are showed a decrease of duriability in quick times of 10~20 years after construction. Therefore, the project of maintenance and management is located a important subject more and more. The maintanence-management of bridges begin from inspection of bridge and this accupy more important part with repairing-reinforcing method. In a point of view liked this, the purpose of this paper is to propose the most rational and useful method for the maintance-management of bridges with comparing and examming inspection kind inspection frequency and judge standard etc. that manage the each organization of Korea and Japan. Also in the bases of this result, hereafter, it will propose the standard idea for the organization etc. of databank of the bridges.

Deteriorated concrete components are repaired using various repair materials for preventing functional deficiencies. However, the durability performance of these materials is not very well investigate. This study aims to examine the dynamic behavior of R/C beams repaired by Polymer, Polymer-Cement and Cemtitious material through dynamic test. Totally 18repaired R/C beams were tested, and the results from dynamic test of beams repaired with various materials were compared.

A series of 15 reinforced concrete beams was tested to evaluate the flexural performance of the repaired RC beams. the key parameters for this study were the repair materials, polymer/cementitious materials, in addition to the strengthening material, steel plates and carbon fiber sheets. The repaired specimens failed by a typical flexural mode. showing minor interface failure. The results show that epoxy, polyester resins and latex modified cementitous mortars are effective for repairing the concrete beams. However, the flexural preformance of the strengthened beams are varied depending on the repaired materal.

P.C box bridges is divided into internal prestressing and extermal prestressing based on arrangement of tendon. In this research the method of establishment of dviation block in advance and analysis of block and the control relationship of tension of external tendon and displacement should be examined by practical example of high speed rail way in aspects of maintenance and repairment.

it is extremely difficult to perform the dynamic experiments with full-scale specimens. For this reason, small-scale structural models offer an attractive means to peform dynamic loading experiments. The purpose of this reserch is to estabilish the reliance for modeling techniques of small-scale specimens subjected to dynamic cyclic loading. This research focused on the similitude requirements for reinforced concrete frame structures subjected to dynamic cyclic loading. Length scale ratio of specimens were 1:2:4, and six specimens were tested at the frequencies of 0.0025Hz~2.0Hz. It was confirmed that modeling techniques based on the similitude requirements were useful method to evaluate the behavior of full-size R/C structures subjected to earthquake type loading.