The purpose of this study is to investigate the effects of reinforcement arrangements on the high strength of concrete and to present the quantitative values. To complete this research, two types of concrete strengths (40 MPa and 60 MPa), two types of reinforcing bar diameters (10 ㎜ and 13 ㎜), and seven types of specimens with or without reinforcement arrangements were prepared and tested for compressive strength. As a result, the strength of the cores containing the reinforcement can be predicted to have 82% - 94% of the strength of the cores without reinforcement.

C-S-H phase is one of the main hydrates in hardened cement paste and binds chloride ions. The purpose of this study is to quantify equilibrium amount of chloride adsorption bound by C-S-H phase with various Ca/Si ratios. C-S-H phase can absorb chloride ions with 3 steps. In the C-S-H phase with low Ca/Si ratios, momentary physical adsorption could not be expected. Physical adsorption is strongly dependent on electro-kinetic interaction between surface area of C-S-H phase and chloride ions. In previous research, C-S-H phase showed binding behavior with 3 stages including the stage of instantaneous physical adsorption other stages. Thus, this study examined the equilibrium amount to express chloride binding isotherm of C-S-H with various Ca/Si ratio.

Filler material (concrete or mortar) has been used for shielding radioactive waste, however, it is proceeded out evaluation for radiation shielding performance. So, it is needed to check the property in the shielding performance. Therefore, in this paper, mechanical properties of concrete was evaluated for the applicability using heavyweight waste glass as fine aggregate of filler material. From the test results, compressive and elasticity modulus were significantly affected by substitution of heavyweight waste glass, however, it could be improved the performance by using mineral admixture as binder.

Effect of confining pressure on the shear strength of ultra-high-performance fiber-reinforced concrete (UHPFRCs) was investigated using a new shear test setup. Different confining pressures were applied and maintained to the specimens prior to shear testing. The shear strength of UHPFRCs was obviously sensitive to the confining pressure: the higher confining pressure produced higher shear strength. The confined shear strength could be expressed as a function of unconfined shear strength, confining pressure, and tensile strength.

Prediction of the compressive strength of the maturity method has been studied by several researchers and has been applied to the construction of concrete structures. In order to apply the maturity method, which is a function related to temperature and time, it is important to measure the accurate temperature inside the concrete during the curing period. The purpose of this study is to verify the performance by analyzing sensitivity, measurement and transmission accuracy by exposing wireless embedded sensor to various curing environment.

This study is to prepare prediction method of the durability establishment for the effective maintenance of reinforced concrete substation structures. For this study, we investigated research trends about the foreign practices relating durability design.

Recently, high-performance and high-fluidity concrete have been studied and developed because high-rised build is constructed. high-performance and self-consolidating concrete is demanded high strength as low w/cm and fluidity as adding superplasticizer. However, these superplasticizer are changed early-age property such as bleeding, segregation and late setting time etc. This study persents the setting time of fluidity mortars evaluated using the measurement of eletrical resistivity. 7th Samples prepared mortars which were adding polycarboxylate type superplasticizer(Ester) or poly naphthalene sulfonate(PNS) and measured the electrical resisitivity during 24 h. As a results, mortars which added superplasticizers were late rising time which is setting time in measurement of electrical resistivity. However, degree of hardening of PNS mortar were higher than Ester mortar.

The purpose of this paper is to clarify the boundary condition of the joint members in the multi-span greenhouse. It is carried out that experiments for the rotational stiffness of the joint members used in both the field and the standards of the greenhouse constructions.

This paper presents a study on the adhesive strength testing of self-adhesive waterproofing/anti-corrosion sheet used for waterproofing of the large diameter steel pipe interior of water treatment facilities. After the sheet has been applied, similar physical and chemical immersion conditions are simulated in the testing to determine the effects of deterioration through adhesion strength testing.

In this study, the expandable shale collected from the same area in Korea is fired to confirm the foamability. The firing uses an electric furnace capable of firing up to 1600 ℃. The shale was classified into three types according to its constituent and apparent characteristics, and each component was analyzed by XRD analysis method. The shale was fired considering the firing temperature and the residence time. As a result of firing, it was found that the firing temperature was different by more than 100 degrees and it was confirmed that the foaming property was increased with increasing temperature

This study is a basic review of the use of CGS generated in IGCC as a fine aggregate for concrete, and a basic feature of cement mortar was considered. The analysis shows that CGS and CS mix ratio is best when the CGS is mixed at about 0~50 % On the basis of workability and strength improvement effects. This is expected to contribute to the strength, workability, and quality improvement of concrete given the optimal mixing of CGS.

The method of lowering the diffusion coefficient of concrete are widely used by mixing blast furnace slag(BFS) and fly ash(FA) in order to prevent the steel corrosion. In this study, the NaCl solution was supplied and the potential of the reinforced steel was monitored to measure the critical chloride contents of the reinforced concrete according to the type of concrete. In case of using BFS and FA, it showed that the corrosion of the steel was progressed rapidly, which is considered to be related to the decrease of the pH of the concrete.

In this study, the correlation with a proctor penetration resistance tester is analyzed for the purpose of judging the setting time of concrete by the convenient portability of the durometer which is a rubber hardness meter.The result of this study showed a high correlation between the value of the tilt of the durometer and the measured value of the proctor penetration resistance tester.

The purpose of this study was to evaluate the direct tensile fracture behavior of fiber hybrid reinforced cement composite by strain rate. Experiment result, it was confirmed that PVA suppressed the microcrack around the steel fiber at the strain rate 101/s, which resulted in the improvement of the pullout resistance of the steel fiber.

This study is an attempt as an introductive investigation on the mechanical characteristics of Vectran fiber cementitious composites. The mixing of Vectran fibers into cementitious binder was tried to fit suitable fiber volume fraction in order to get of high-ductile and high-strength cementitious composites. Compressive and tensile strengths of the composite were evaluated.

This study evaluated the influence of nozzle shapes in the orientation of fibers in cementitious materials. The nozzle shapes involved in the study are conventional, balded, and tapered circulars. The results showed that both the bladed and tapered nozzles increased the control performance of fiber orientation compared to the conventional nozzle. In particular, bladed nozzle was more effective in controlling the fiber orientation.

This study evaluated the orientation control of steel fibers in cementitious materials using magnetic field. With the increases in the range of the magnetic field, the effective length of the orientation control of the steel fiber is increased and the orientation control effect is larger.

In this study, poly-silicon sludge was used in replacement with Portland cement as SCMs. Poly-silicon sludge has an ability to improve the durability to the concrete system. Thus, the chloride penetration test of PS specimens was conducted for the confirmation of the durability. From the results, The penetration depth of the plain specimens is deepest, and gradually decreases as PS substitution rate increases.

In this study, the performance of the self-healing with the granulated alkali activator (Ca(OH)2) manufactured in seawater environment is investigated for crack healing under 300 μm of cracks. Specimens combined with GGBFS and OPC with and without the granulated alkali activator were manufactured and immersed in seawater. After that, crack recovery on the surface of the specimens with the granulated alkali activator (Ca(OH)2) was also evaluated by the ultrasonic pulse velocity test. From the results, it was verified that cementitious materials with the granulated alkali activator, exposed in marine environments, could be able to heal or seal inside cracks

The purpose of this experimental study is to investigate the influence of chemical resistance of porous concrete using high performance nano TiO2 Carrier. As a result, porous concrete using high performance nano TiO2 Carrier was confirmed to be superior than ordinary concrete and TiO2 concrete chemical resistance.