• Structural Engineering and Mechanics
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• 제88권2호
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• pp.141-157
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• 2023

In the present paper, the effect of recycled aggregates on the rheological and mechanical properties of self-consolidating concrete is investigated experimentally and numerically. Hence, the specimen with two types of recycled aggregates, i.e., known and unknown resistance origins, are utilized for the studied specimens. The experiments in this study are designed using the Box-Behnken method, which is one of the response surface methods. Input variables in mixtures include silica fume in the range of 5-15% as a percentage substitute for cement weight and recycled coarse and fine aggregates in the range of 0-50% for both series of recycled materials as a substitute for natural materials. The studied responses are slump flow, V funnel, compressive strength, tensile strength, and durability. The results indicate that the increase in the amount of recycled aggregates reduces the rheological and mechanical properties of the mixtures, while silica fume effectively improves the mechanical properties. In addition, the results demonstrate that the fine recycled aggregates affect the total response of the concrete significantly. The results of tensile and compressive strengths indicate that the mixtures including 50% recycled materials with known resistance origin demonstrate better responses up to 8 and 10% compared to the materials with unknown resistance origins, respectively. Recycled materials with a specific resistance origin also show better results than recycled materials with an unknown resistance origin. Durability test results represent those concretes containing recycled coarse aggregates have lower strength compared to recycled fine aggregates. Also, a series of mathematical relationships for all the responses are presented using variance analysis to predict mixtures' rheological and mechanical properties.

• 한국건설순환자원학회논문집
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• 제7권4호
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• pp.128-135
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• 2012

ALC는 경량이며 단열 및 차열 등의 성능이 우수한 반면 낮은 강도로 인한 모서리부의 취성파괴가 발생하기 쉬우므로 운반 및 취급 시 상당한 주의를 요구한다. 본 연구에서는 ALC의 물리적 성능개선을 위해 메타카올린 및 실리카퓸 등의 혼화재나 규석 분말 및 석고의 혼입율을 조절하여 제조한 ALC의 성능을 평가하였다. 연구결과 메타카올린이나 규석 분말의 혼입율이 18%인 경우 강도의 개선이 현저하였다. 이와 같은 결과는 공극의 충전효과에 의한 것으로 강도는 개선되나 밀도가 증가하므로 밀도를 낮추면서 강도를 개선할 수 있는 배합이나 제조법에 대한 연구가 필요하다.