PURPOSES: The objective of this study is to evaluate the properties of high-performance concrete and compare them with the properties of ternary blended cement (OPC 60% : BFS 30% : FA 10%) as applied to all-in-one bridge decks. High-performance concrete modified with styrene-butadiene latex (SB latex) was evaluated for strength development and durability through its compressive strength and chloride ion diffusion coefficient. METHODS: The compressive strength test was conducted according to KS F 2405, and the average value of the three specimens was used as the result at each stage. The chloride ion diffusion test was performed at 28 days, 56 days, and 365 days according to NT BUILLD 492. The chloride ion penetration test was conducted according to ASTM C 1202. RESULTS: For the compressive strength of the high-performance concrete, the blast furnace slag 40% replacement (BFS40) mixture had the most similar results to those of the ternary blended cement. The BFS40 mixture exhibited a lower compressive strength at 3 days than the latex modified concrete (LMC) mixture used for the bridge deck pavement, whereas it exhibited a 3.7-9.8% higher compressive strength at 7 days. In addition, the BFS40 mixture had the lowest diffusion coefficient, which was 49.1~59.0% lower than that of the LMC mixture. Mixing with latex tended to decrease in charge passed compared to Plain which is only used ternary blended cement, and showed excellent watertighness (rated “very low”), which is lower than 1,000 coulombs in all mixtures with latex. CONCLUSIONS : The BFS40 mixture exhibited excellent compressive strength, chloride ion permeability resistance, and the lowest chloride ion diffusion coefficient although it included a small amount of latex, which makes it more expensive than the current LMC mixture. It is believed that it is possible to secure excellent economic efficiency and durability by using lesser latex than that in the LMC mixture and using a mixture of the blast furnace slag instead.

Recent changes in the construction method of piles to minimize noise, along with the development of high-strength reinforcement, have provided an economical high performance RC pile development to compensate for the disadvantages of existing PHC piles. In this study, a methodology for the development of cross - section details of high performance RC piles of various performances is presented by freely applying high strength steel and concrete. This study suggested a technique for calculating bending moments for a given axial force corresponding to the allowable crack widths and this can be used for serviceablity check. In calculating the design shear force, the existing design equation applicable to the rectangular or the I section was modified to be applicable to the hollow circular section. In particular, in the limit state design method, the shear force is calculated in proportion to the axial force, and the procedure for calculating PV diagram is established. Last, the section details are determined through PM diagrams that they have the similar flexural and axial-flexural performances of the PHC pile A, B and C types with a diameter of 500 mm. To facilitate the application of the selected standard sections to the practical tasks, the design PM diagram and design shear forces are proposed in accordance with the strength design method and limit state design method.

Seismic performance of ordinary reinforced concrete shear wall systems commonly used in high-rise residential buildings is evaluated. Three types of shear walls exceeding 60m in height are designed by performance-based seismic design. Then, incremental dynamic analysis is performed collapse probability is assessed in accordance with the procedure of FEMA P695. As a result, story drift, plastic rotation, and compressive strain are observed to be major failure modes, but shear failure occur little. Collapse probability and collapse margin ratio of performance groups do not meet requirement of FEMA P695. It is observed that critical wall elements fail due to excessive compressive strain. Therefore, the compressive strain of concrete at the boundary area of the shear wall needs to be evaluated with more conservative acceptance criteria.

PURPOSES: This paper presents the noise reduction effect of asphalt concrete pavement using steel slag aggregate. METHODS: Steel slag aggregates induce various mechanical effects because of their high stiffness and specific gravity. It is also known that the noise reduction effect is due to its high specific gravity and porous nature. In this study, the noise reduction in a steel slag asphalt concrete pavement section was measured and analyzed. RESULTS : On average, an asphalt concrete pavement with steel slag reduces road traffic noise by about 2 dB(A). In addition, the analysis of sound pressure levels by frequency showed lower sound pressure levels in steel slag asphalt concrete pavement than general HMA in all frequency ranges (from low to high frequencies). An analysis of the benefits with regard to noise, by assuming a road-traffic noise reduction of 2 dB(A) with asphalt concrete pavement using steel slag, shows that the noise abatement cost approach can save 1.6 million won a year over soundproof wall costs. In addition, the noise damage cost approach results in cost savings (with regard to noise) of between 19 and 60 million won per year depending on the population density. CONCLUSIONS: The use of steel slag aggregate as an asphalt concrete mixture material not only improves the mechanical performance but also has a noise reduction effect. It is expected that the steel slag asphalt concrete pavement can reduce the environmental burden by utilizing resources and provide a safer and more comfortable pavement condition to the road users.

PURPOSES: This study was conducted to investigate the causes of damage and to suggest proper repair methods for the sections in which a number of transverse cracks and faulting occurred in JCP (Jointed Concrete Pavement) slabs during the early-age performance period. METHODS: Field crack survey, FWD (Falling Weight Deflectometer) investigation, dowel bar installation condition survey, longitudinal profile survey, and in-situ core specimen inspection were conducted. . RESULTS : As a result of the analysis, it was found that there was no decline in the composite modulus of the subgrade reaction (k-value). The dowel bars were properly installed, but the LTE (Load Transfer Efficiency) of the joint and transverse cracks were analyzed to be very low. In addition, it was found that there are voids in the bottom of the slab at the joints and corners. Due to the excessive built-in curling in the early age of concrete pavement construction, upward curling displacement occurred at the joints and corners, resulting in voids at the bottom of the slab. As a result, it was found that transverse cracks occurred due to the defective joint LTE. CONCLUSIONS: Excessive built-in curling can cause early age cracks in the JCP slabs. In order to minimize the occurrence of reflection cracks after the application of the asphalt overlay in the future, concepts of alternative repair methods were proposed.