• 한국구조물진단유지관리공학회 논문집
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• 제19권2호
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• pp.125-132
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• 2015

본 연구에서는 석회석 미분말을 이용하여 제조한 콘크리트의 굳지 않은 및 굳은 특성을 실험적으로 평가하였다. 석회석 시멘트 제조시 석회석 혼입률은 10%, 15%, 25% 및 35% 범위이며, 보통 포틀랜드 시멘트를 이용하여 제조한 기준 콘크리트 (OPC)와 비교하였다. 혼입률 35%까지 슬럼프, 공기량의 굳지 않은 특성은 기준 시험체와 유사한 특성을 나타내었지만 혼입률이 증가할수록 응결시간은 지연되었다. 석회석 혼입률 15%까지는 압축 및 휨강도, 급속 동결융해 저항성능의 경우 기준 OPC 콘크리트와 동등수준을 확보할 수 있는 것으로 나타났지만, 탄산화 저항성능 향상을 위한 보완은 필요한 것으로 나타났다. 혼입률 25%, 35% 배합은 기준 콘크리트 성능에 비해 압축강도 및 휨강도의 저하가 발생되었다. 치환률이 증가할수록 제한된 수산화칼슘량으로 인해 탄산화 저항성능은 모든 배합에서 감소하였다. 강도감소 및 탄산화저항성능을 고려할 경우, 15% 수준의 석회석 미분말 치환은 가능할 것으로 판단된다.

• Advances in concrete construction
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• 제10권6호
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• pp.515-526
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• 2020

Cold-mixed asphalt mixture is a widely recommended asphalt pavement materials with potentially economic and environmental benefits. Due to the reduction of natural non-renewable mineral resources, powder minerals with similar properties are considered as new mineral fillers in asphalt mixtures. This study explored the feasibility of using cement to replace natural limestone powder (LP) in emulsified asphalt concrete modified by styrene-butadiene styrene copolymer. The experimental tests, including compressive strength, Marshall stability as well as moisture susceptibility test, were used to investigate the mechanical properties, the Marshall stability, flow value, as well as the moisture damage. In addition, the influence of material composition on the performance of asphalt concrete is explained by the microstructure evolution of the pore structure, the interface transition zone (ITZ), and the micromorphology. Due to mineralogical reactivity of cement, its replacement part of LP improved the mechanical properties, Marshall stability, but it will reduce the moisture susceptibility and flow value. This is because with the increase of the cement substitution rate, the pore structure of the asphalt concrete is refined, the width of ITZ becomes smaller, and the microstructure is more compact. In addition, asphalt concrete with a larger nominal particle size (AC-16) has relatively better performance.

• Advances in concrete construction
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• 제6권1호
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• pp.69-85
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• 2018

In order to provide sufficient stability and resistance against bleeding and segregation during transportation and placing, mineral admixtures are often used in self-compacting concrete mixes (SCC). These fine materials also contribute to reducing the construction cost and the consumption of natural resources. Many studies have confirmed the benefits of these mineral admixtures on properties of SCC in standard curing conditions. However, there are few published reports regarding their effects at elevated curing temperatures. The main objective of this study is to investigate the effect of three different mineral admixtures namely limestone powder (LP), granulated blast furnace slag (GS) and natural pozzolana (PZ) on mechanical properties and porosity of SCC when exposed to different curing temperatures (20, 40, 60 and $80^{\circ}C$). The level of substitution of cement by mineral admixture was fixed at 15%. The results showed that increasing curing temperature causes an improvement in performance at an early age without penalizing its long-term properties. However the temperature of $40^{\circ}C$ is considered the optimal curing temperature to make economical and high performance SCC. On the other hand, GS is the most suitable mineral admixture for SCC under elevated curing temperature.