基于科式芽孢杆菌矿化沉积的混凝土裂缝自修复性能试验研究

Experimental study on self-healing performance of concrete cracks based on mineralization of Bacillus cohnii

混凝土材料具有脆性大、抗拉强度较低等特点,导致其内部或表面难以避免出现微裂缝。基于微生物矿化沉积的裂缝自修复技术能够有效地实现混凝土裂缝的自诊断和自修复。以具有嗜碱特性的科式芽孢杆菌为自修复剂,以膨胀珍珠岩为修复剂载体,研制出一种新型裂缝自修复混凝土。分别对普通混凝土、采用直接掺菌的混凝土和研制的自修复混凝土的裂缝自修复能力进行试验研究。试验结果表明,在裂缝修复早期,裂缝内表面未水化胶凝材料的水化反应致使裂缝宽度小于0.2 mm的普通混凝土试件具有较好的自修复能力;随着裂缝修复时间的增长,基于科式芽孢杆菌矿化沉积的混凝土试件具有更优异的自修复能力,水中养护28 d后研制的自修复混凝土最大修复裂缝宽度可达0.56 mm。研究结果可为混凝土裂缝自修复技术研究提供技术支持和依据。

It is unavoidable for the formation of cracks on internal or surface of concrete due to drawbacks of concrete such as brittle and low tensile strength.The self-healing technique based on microbial mineralization can effectively realize the self-diagnosis andself-healing of concrete cracks.Bacillus cohnii and expanded perlite are used as self-healing agent and agent carrier respectively, and a new type of self-healing concrete is proposed.Furthermore,the self-healingcapacity of normal concrete, directly mixed bacteria concrete and proposed self-healing concrete were investigated respectively.It shows that the normal concrete specimen exhibited better self-healing capacity of cracks of which width were less than 0.2 mm in the early age.This phenomenon may be due to the hydration reaction of the un-hydrated cementitious material on the inner surface of cracks.While,the concrete specimens based on aerobic microbial mineral deposition exhibited more excellent self-healing capacity with the increase of healing time,and the maximum healing width of crack is 0.56 mm after 28 days＇ curing in water.The results of this study can provide technical support and basis for the further research on self-healing technology of concrete crack.