基于微生物矿化的水泥基材料表面防护及裂缝修复

Surface Protection and Crack Repair of Cement-based Materials Based on Microbial Mineralization

微生物诱导碳酸钙沉淀技术是一种比较新颖、绿色环保的混凝土修复技术。针对混凝土工程裂缝等缺陷,试验研究微生物水泥对混凝土表面及裂缝的修复防护效果。研究表明,试件表面先涂覆菌液再喷洒营养液,经多次修复后,试件表面均被沉积的碳酸钙膜层覆盖,表面裂缝也均被封闭,覆膜层坚硬、致密。试件毛细吸水系数得以大幅降低,降低率达90%以上,修复效果的表征应采用毛细吸水系数及毛细吸水系数降低率综合评价。裂缝中填入石英砂(粉)作为修复基材,经微生物水泥多次注入后抗折强度均得到了不同程度的提高,特别是缝宽3.0 mm试件修复后的抗折强度最高恢复至原基准试件的78%,抗折强度提高了74%,修复效果明显;其他缝宽试件的抗折强度恢复率为60%~68%,提高率为18%~30%,裂缝越宽,修复效果相对越好。

Microbial induced calcium carbonate precipitation(MICP)is a kind of novel and environment-friendly technology to repair concrete cracks.Aiming at cracks and other defects in concrete engineering,the protective effect of microbial cement on concrete surface and cracks is studied by experiments.The results show that after the specimen surface is coated with bacteria solution and then sprayed with nutrient solution,the specimen surface is covered with deposited calcium carbonate film after repeated restoration,the surface cracks are closed,and the film coating layer is hard and dense.The capllary water absorption coefficient of specimens is greatly reduced and the reduction rate is more than 90%.The comprehensive evaluation of capillary water absorption coefficient and reduction rate of capillary water absorption coefficient should be used to characterize the restoration effect.When the fracture is filled with quartz sand(powder)as repair based material,the flexural strength can be improved in different degrees after multiple injection of microbial cement.Especially,the maximum flexural strength of the specimen with a crack width of 3.0 mm is recovered to 78%of the flexural strength of the original reference specimen,which is increased by 74%.The recovery rate of flexural strength of the specimens with other crack width is 60%to 68%,and the improvement rate is 18%to 30%.The wider the crack,the better the repair effect is.