• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2007년도 추계 학술논문 발표대회
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• pp.67-70
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• 2007

In this study, the characteristic of strength development of high volume fly ash concrete(HVFAC) was experimentally investigated. The production of one ton of portland cement releases about 0.87ton of CO2 into the atmosphere. HVFAC is an emerging material technology and is environmentally friendly because of its reduced use of portland cement, reduced CO2 emissions. For this purpose, two levels of W/B were selected. Seven levels of fly ash replacement ratios and two levels of silica fume replacement ratios were adopted. In the concrete mix, the water content of 125kg/m3 was used, which is less than that of usual water content. As a result, it was observed that the slump of concrete was increased with the increasing fly ash replacement ratio and when the silica fume was incorporated into the concrete, the slump was significantly decreased at the same condition. It appeared that the compressive strength gradually decreased with increasing fly ash replacement ratio at the early age, but the difference of strength up to replacement ratio of 50% was little at the age of 91 days because of the pozzolanic reaction of fly ash.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2021년도 봄 학술논문 발표대회
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• pp.72-73
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• 2021

For the development of high-fluidity concrete using low-binder, The effect of the use of the developed acrylic viscosity agent on the physical properties of concrete evaluated. The amount acrylic viscosity agent used was 1.5%, 1.7%, and 2.0% based on the binder amount of 400kg/m3, and slump flow test, slump flow 500mm arrival time measurement, air volume measurement, and U-Box passing test were conducted to determine the effect of the physical properties of concrete. it was judged that 1.5% of the acrylic viscosity agent used in high-fluidity concrete using low-binder was most suitable.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2021년도 가을 학술논문 발표대회
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• pp.129-130
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• 2021

For the development of high-fluidity concrete using low-binder, The effect of the use of the developed acrylic viscosity agent on the physical properties of concrete evaluated. The amount acrylic viscosity agent used was 0.28%, 0.29% and 0.30% based on the binder amount of 350kg/m³, and slump flow test, air volume measurement, U-Box passing test and strength compressive were conducted to determine the effect of the physical properties of concrete. it was judged that 0.29% of the cellulose type viscosity agent used in high-fluidity concrete using low-binder was most suitable.

• 한국건축시공학회지
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• 제3권3호
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• pp.135-142
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• 2003

This study is for the great quantity use of fly-ash. For the producing of high volume concrete from the use of fly-ash, the method of replacement between bonding agents and fine aggregate by fly-ash was used at the same time. It was used that the adiabatic temperature rise of concrete about the mass member which had been produced by the method that was mentioned before, and the hydration heat of the core test pieces in concrete was measured. Also the core test pieces which were replaced with fly-ash was studied by the compressive strength's comparison between standard care test pieces and core test pieces. In the case of mass test pieces, hydration heat and the time to reach the highest temperature were decreased by an increase in replaced fly-ash's amounts of concrete. In addition, among the test pieces having the same amounts of concrete, the test pieces having more replaced amounts of fly-ash's fine aggregate showed higher hydration heat and the increased time to reach the highest temperature. Compressive strength was also increased by hydration heat's decrease according to fly-ash replacement. Replacement of fly-ash was more effective in high temperature environment.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2003년도 학술.기술논문발표회
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• pp.67-71
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• 2003

This study is for the great quantity use of fly-ash. For the producing of high volume concrete from the use of fly-ash, the method of replacement between bonding agents and fine aggregate by fly-ash at the same time was used. It was used that the adiabatic temperature rise of concrete about the mass member which bad been produced by the method that was mentioned before, and the hydration heat of the core test pieces in concrete was measured. Also the core test pieces which were replaced with fly-ash was studied by the compressive streneth's comparison between standard care test pieces and core test pieces. In the case of mass test pieces, hydration heat and the tine to reach the highest temperature were decreased by an increase in replaced fly-ash's amounts of concrete. In addition, among the test pieces having the same amounts of concrete, the test pieces having more replaced amounts of fly-ash's fine aggregate showed higher hydration heat and the increased time to reach the highest temperature. Compressive strength was also increased by hydration heat's decrease according to fly-ash replacement. Replacement of fly-ash was more effective in high temperature environment.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2015년도 추계 학술논문 발표대회
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• pp.185-186
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• 2015

The Standard penetration test determines the type of soil according to soil bearing capacity, and this classifies the subsoil into many layers. Construction project managers are willing to know the depth of the present types of subsoil on site in order to make plans on earthwork stage during excavation. However the standard penetration test may not provide accurate information on subsoil type due to incorrect spacing. To solve this problem, this study propose a conceptual algorithm for determining the spacing of standard penetration test spots to essentially tests relevant locations on which to be applied the standard penetration test. This provides the acquirement of the accurate layered model volume of earthwork revised into geological columnar section. This algorithm will determine the appropriate standard penetration test spots spacing on a given size of site to optimize the accuracy of the earthwork volume, time and cost.

• 한국건축시공학회지
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• 제11권4호
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• pp.379-386
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• 2011

Durability of concrete is an important issue, and one of the most critical aspects affecting durability is chloride diffusivity. Factors such as water.cement ratio, degree of hydration, volume of the aggregates and their particle size distribution have a significant effect on chloride diffusivity in concrete. The use of polypropylene fibers(particularly very fine and well dispersed micro fibers) or mineral additives has been shown to cause a reduction in concrete's permeability. The main objective of this study is to evaluate the manner in which the inclusion of fiber(in terms of volume and size) and blast furnace slag(BFS) (in terms of volume replacement of cement) influence the chloride diffusivity in concrete by applying 3D computer modeling for the composite structure and performing a simulation of the chloride penetration. The modeled parameters, i.e. chloride diffusivity in concrete, are compared to the experimental data obtained in a parallel chloride migration test experiment with the same concrete mixtures. A good agreement of the same order is found between multi.scale microstructure model, and through this chloride diffusivity in concrete was predicted with results similar to those experimentally measured.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2014년도 춘계 학술논문 발표대회
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• pp.146-147
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• 2014

In this study, as the resistance of the carbonation for high volume admixture incorporating concrete, coating effect of using refined cooking oil in the surface of high volume admixture incorporating concrete has been tested. The following results could be made as the conclusion. For the fresh concrete, the slump and air content has been identified as satisfying the target range. For the hardened concrete, comparing with specimen of Plain, specimen with coating showed better long age compressive strength. For the carbonation speed, the specimen of FA30 showed highest speed and the specimen of BS60 showed higher speed than specimen of Plain. For all the specimens coated with RCO, as the decrease of capillary pores inside the concrete, the carbonation speed has been obviously decreased and with even better effect than using PEP coating. It could be identified that specimens with coating by RCO showed good effect on refrain the speed of carbonation.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2023년도 봄 학술논문 발표대회
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• pp.183-184
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• 2023

The purpose of this study is to compare and analyze the effect of type and volume fraction of fiber on the electrical conductivity and shielding effectiveness of cementitious composites. The large specific surface area of amorphous metallic fiber, as well as the high number of fibers per unit weight, provided an advantage in the formation of conductive path. As the result, the electrical conductivity of amorphous metallic fiber was evaluated to be higher, and the shielding effectiveness was also higher. However, the shielding effectiveness according to electrical conductivity was confirmed to have a threshold point, and further research is needed to improve it.

• 한국건축시공학회지
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• 제13권1호
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• pp.20-28
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• 2013

Flexure toughness of Steel Fiber Reinforced Concrete (SFRC) shows a time-dependent characteristic due to the hydration process of the cement matrix in the SFRC system. The effect of two important factors, water/cement (w/c) ratio and fiber volume fraction, on the flexure toughness development of SFRC were investigated. Three different SFRC mixtures with hooked-end steel fibers were tested using a four-point bending testing configuration. Each mixture was tested at five different ages. The results showed that the post-peak toughness of SFRC developed at an earlier age than the first-crack toughness.