1 School of Materials Science and Engineering, Southeast University, Nanjing 211189, China 2 Research Center of Green Building and Construction Materials, Southeast University, Nanjing 211189, China
Abstract: In order to achieve the efficient utilization of waste concrete sand and powder, using waste sand as the core, waste powder and a small amount of cementing material as the shell material, cold-bonding technology is used to prepare recycled coarse aggregates with core-shell structure, and microbially induced calcium carbonate precipitation (MICP) is integrated with the purpose of strength enhancement. This paper studies the effects of mineralization time, calcium ion concentration on the core mass gain and water absorption, the amount of cementitious material on the granulation rate, and the content of microbial mineralizer on the properties of recycled coarse aggregate, SEM and TG-DTG were used to analyze the morphology and phase content of recycled coarse aggregate. Experimental results indicate that mineralized microorganisms can accelerate and induce calcium carbonate deposition, and significantly improve the quality of recycled coarse aggregates. When the content of microbial mineralizer is 1.0%, the crushing index of recycled coarse aggregates, water absorption, content of fine powder and soundness decreased by 50.0%, 21.2%, 50.0%, and 15.3%, and the apparent density increased by 2.8%, the shell calcium hydroxide was completely mineralized, and the calcium carbonate content increased to 24.18%.
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2021, Vol. 35 
