• Journal of the Korean Recycled Construction Resources Institute
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• v.7 no.1
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• pp.82-91
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• 2019

In this study, in order to evaluate Hydration Heat Characteristics of mass concrete using ternary blended cement for large underground structures, the analysis considering the temperature history and the thermal characteristics inside the actual structure was performed. The results of the analysis are compared with the measured values to verify the reliability of the analysis and to evaluate the crack resistance performance. As a result of the measured the actual structure temperature, The adiabatic temperature rise coefficients K and ${\alpha}$ of the slab were $35.1^{\circ}C$ and 0.72, respectively, and the wall was analyzed as $29.3^{\circ}C$ and 0.67. The analytical results and the correlation coefficients(r) were 0.95 and 0.98, respectively. As a result of evaluating the crack resistance of slab and wall, the minimum crack index of slab and wall was 1.22 and 1.20, respectively. These results were found to satisfy the site management standards.

• Journal of the Korea Concrete Institute
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• v.13 no.5
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• pp.476-483
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• 2001

초유동콘크리트는 유동성 증진 및 충전성 향상을 위해 단위분체량을 크게하기 때문에 콘크리트의 고강도화와 수화발열량을 증가시키는 문제점을 가지고 있다. 이에 본 연구는 초유동콘크리트의 강도조절과 수화열 저감을 위해 쇄석분을 이용하여 초유동콘크리트의 강도, 유동성, 내구성능 및 건조수축 특성을 검토하였다. 실험결과 쇄석분은 치환율 10% 증가시마다 무치환시의 압축강도를 약 10~15%씩 감소시키며, 변형계수와 물구속비를 감소시켜 초유동콘크리트의 유동성 향상에 효과적이다. 또한 초유동콘크리트에서 쇄석분 10%치환시 마다 단위시멘트량 감소에 따른 최고 단열온도상승량을 약 4$^{\circ}C$씩 감소시켰다. 반면 건조수축량은 10%치환시 마다 약 5%증가시켰다. 한편 초유동콘크리트의 내구성능은 단위분체량과 유동성향상에 따른 조직의 치밀화로 쇄석분 치환에 관계없이 상대동탄성계수 90%이상으로 우수하게 나타났다. 이와 같이 분체로서 쇄석분 사용은 치환량에 따른 초유동콘크리트의 강도조절이 가능하며 수화발열량을 저감시킬 수 있다. ^ x Super flowing concrete causes high strength and the increase of heat of hydration because of the big unit powder content of concrete to increase flowability and to improve compact of concrete. Therefore, this study investigates the characteristic properties of strength, flowability, durability and drying shrinkage to control strength and to reduce heat of hydration of super flowing concrete using crushed stone fines. According to the experimental results, when crushed stone fines are increased every 10%, 10~15% of compressive strength is decreased and flowability of super flowing concrete is effectively improved due to the decrease of modulus of deformation and confined water ratio. When crushed stone fines are replaced every 10%, 4$^{\circ}C$ of the highest adiabatic temperature rise is decreased by reducing the unit cement. However, 5% of drying shrinkage is increased in the same condition. In the meantime, durability of super flowing concrete is excellent, having over 90 % of good relative dynamic modulus of elasticity due to fineness of formation caused by the increase of the unit powder content and the improvement of flowability, without regard to the replacement of crushed stone fines. Therefore, it can be said that the usage of crushed stone fines can control the strength of super flowing concrete by replacement and reduce heat of hydration.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.1
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• pp.1-8
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• 2019

Phase change material(PCM) has the capacity to absorb or release energy in heat when the phase changes. This study conducted to investigate the effect of strontium-based PCM on the hydration heat and mechanical properties of mortar with fly ash and blast furnace slag. The amounts of PCM were 1%, 2%, 3%, 4%, and 5% by the cementitious materials weight. The tests about mortar flow, semi-adiabatic temperature rise, compressive and flexural strength tests were carried out for twelve types of mortar mixtures. The test results indicated that the use of PCM was effective to reduce hydration heat and retard hydration of mortar with industrial by-products. In particular, the heat generation rate of mortars with fly ash was lower than that of mortars with blast furnace slag. The compressive strength of mortar with fly ash and blast furnace slag were decreased with increasing PCM ratio.