关键词: 再生粗骨料, 再生混凝土, 微生物矿化, 混菌, 裂缝自修复, 骨料增强

Abstract: Microbially induced carbonate precipitation (MICP) can effectively heal the cracks of concrete. However, suitable carriers should be adopted to reduce the adverse effect of cement hydration and high alkalinity. Recycled coarse aggregates (RCAs) are favorable bacteria carrier to prepare self-healing concrete. Meanwhile, MICP can effectively enhance the physical and mechanical properties of RCAs. A self-healing recycled concrete, based on RCAs enhanced by MICP of mixed cultures of bacteria, was proposed to ensure its sufficient mechanical properties and excellent self-healing capacity. A kind of alkaliphilic and aerobic mixed cultures of bacteria with high MICP capacity was firstly enriched and selected. Then, the self-healing recycled concrete was prepared using the RCAs enhanced by MICP of mixed cultures of bacteria. The self-healing capacity of concrete was subsequently investigated. It shows that MICP of mixed cultures of bacteria can effectively enhance the physical and mechanical properties of RCAs. The RCAs enhanced by MICP of mixed cultures of bacteria for 5 d can effectively immobilize the mixed cultures of bacteria. The concrete specimens with mixed cultures of bacteria exhibit much better self-healing capacity compared with specimen with pure culture. The concrete specimens using RCAs as bacterial carrier exhibit better self-healing capacity compared with specimen using ceramsite. The value of completely healed cracked width is up to 0.47 mm. The results of the present study are expected to provide a reference for resource utilization of construction waste and durability of recycled concrete.

Key words: recycled coarse aggregate, recycled concrete, microbially induced carbonate precipitation, mixed cultures of bacteria, self-healing of crack, aggregate enhancement