微生物矿化沉积技术强化核壳结构再生粗骨料

Microbially Induced Calcium Carbonate Precipitation Strengthening Recycled Coarse Aggregate with Core-shell Structure

为实现废弃混凝土砂粉的高效利用,以废弃砂为内核,废弃粉及少量胶凝材料为壳层原料,采用冷粘成球技术制备核壳结构再生粗骨料,并利用微生物矿化沉积碳酸钙(MICP)提升骨料品质,本工作研究了矿化时间、钙离子浓度对内核质量增加率、吸水率的影响,及微生物矿化剂对再生粗骨料性能的提升效果,通过SEM、TG-DTG分析再生粗骨料内核及表面形貌、物相含量。结果表明,矿化微生物可加速、诱导碳酸钙沉积,密实结构,显著提升再生粗骨料品质;当微生物矿化剂掺量为1.0%(质量分数)时,再生粗骨料压碎指标、吸水率、微粉含量、质量损失率分别降低50.0%、21.2%、50.0%、15.3%,表观密度增加2.8%,壳层氢氧化钙完全矿化,碳酸钙含量增至24.18%。

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%.