增强再生骨料固载混菌对混凝土裂缝自修复性能的影响试验研究

Experimental study on the effect of microbial consortia-enhanced recycled concrete aggregates on the self-healing performance of concrete cracks

微生物诱导碳酸钙沉淀可实现混凝土裂缝的自修复,微生物载体可以有效提高混凝土基体内部微生物存活率,从而改善混凝土的自修复效果,然而目前的载体存在力学性能差、与水泥基材料兼容性差以及费用高等问题。提出一种基于增强再生骨料固载混菌的裂缝自修复混凝土,通过再生骨料增强时间对混凝土抗压强度和自修复性能的影响研究,确定再生骨料合理矿化增强时间,并揭示再生骨料矿化增强和混凝土裂缝自修复机理。结果表明:再生骨料合理增强时间为7 d,矿化增强后再生骨料的吸水率和压碎指标降低幅度分别为20.5%和9.5%;混凝土抗压强度提高幅度为8.6%;经56 d的修复养护后,基于增强再生骨料固载微生物的混凝土裂缝平均修复宽度和完全闭合率分别达到了0.44 mm和73%;再生骨料表面沉淀物呈规则方块状、晶体类型为方解石,裂缝部位沉淀物呈规则的方块状和针簇状,晶体类型为方解石和文石。

Microbial induced carbonate precipitation can achieve the crack self-healing in concrete.Bacterial carrier can effectively improve the survival rate of bacteria in concrete matrix and thus improve the crack selfhealing effect in concrete.However,the potential decrease in mechanical properties,poor compatibility with the cementitious matrix and relatively high cost of the current bacterial carrier cannot be ignored.The self-healing concrete based on enhanced recycled concrete aggregate as bacterial carrier is proposed in this paper.The influence of enhancement time of recycled concrete aggregate on compressive strength and self-healing capacity of concrete was studied to determine the reasonable mineralization enhancement time of recycled concrete aggregates,and the enhancement mechanism of recycled concrete aggregates and self-healing mechanism of concrete are revealed.The experiment result shows that the reasonable enhancement time of recycled concrete aggregates is 7 days,the water absorption and crushing index of enhanced recycled concrete aggregates decrease by 20.5% and 9.5%,the compressive strength of concrete prepared with the enhanced recycled concrete aggregates increased by 8.6%.After 56d of curing and healing,the average value of healed crack widths and completely healing percentages of the concrete prepared with enhanced recycled concrete aggregates are 0.44 mm and 73%,respectively.The surface precipitates on the enhanced recycled concrete aggregates exhibit regular cubic shapes and the crystals of these precipitates are calcite.The crack-filling precipitation crystals of the self-healing concrete exhibit regular cubic shapes and cluster shapes.The crystals of these precipitations are calcite and aragonite.