不同钙源对微生物自修复混凝土裂缝的修复效果及其机理分析

the Effect and Mechanism of Different Calcium Sources on Microbial Self-healing Concrete Cracks

本研究在模拟裂缝区溶液中,研究了不同钙源下溶液中的Ca^(2+)浓度和钙沉淀能力的变化。制备了微生物自修复砂浆试件,研究含不同钙源的微生物修复剂对砂浆试件强度的影响;以面积修复率和吸水率来评价0.25~0.40 mm裂缝的自修复效果,并研究了裂缝的修复方向。此外,通过扫描电镜和X射线衍射仪分析了砂浆试件裂缝区的修复产物,并详细探讨了不同钙源对砂浆裂缝的自修复机理。研究结果表明,在不同钙源下,枯草芽孢杆菌的矿化机理是不同的,造成了溶液中Ca^(2+)浓度和钙沉淀能力的差异,并且钙源也会影响微生物自修复砂浆的抗折抗压强度。当钙源为乳酸钙时,砂浆裂缝的修复效果最好,其次是醋酸钙和硝酸钙。在裂缝修复过程中,修复产物从裂缝表面往裂缝内部生成,因而随着裂缝深度的增加,修复产物的生成量逐渐降低,并且砂浆试件裂缝处的白色物质主要是方解石碳酸钙。本研究证明了微生物诱导碳酸钙沉积(MICP)技术可以较好地应用于水泥基材料裂缝的自修复,有利于推动微生物自修复混凝土的发展与进步。

The changes of Ca^(2+)concentration and calcium precipitation capacity with different calcium sources were studied in the simulated crack zone solution.Then,microbial self-healing mortar specimens were prepared and the effects of microbial healing agents containing different calcium sources on the strength of mortar specimens were studied.Afterwards,the self-healing efficiencies of 0.25-0.40 mm crack were evaluated by the area repair ratio and water absorption ratio,and the self-healing direction of crack was studied.In addition,the healing products at the crack mouth of mortar specimens were analyzed by SEM and XRD,and the self-healing mechanism of different calcium sources on mortar cracks was discussed carefully.The test results showed that the mineralization mechanism of Bacillus subtilis was different under different calcium sources,resulting in the differences of Ca^(2+)concentration and calcium precipitation capacity in the solution,and the calcium source would also affect the flexural and compressive strength of microbial self-healing mortar.At the same time,w When the calcium source was calcium lactate,the self-healing effect of mortar cracks was the best,followed by calcium acetate and calcium nitrate.In the process of crack repair,the healing products were generated from the crack surface to the inside of crack.With the increase of the crack depth,the amount of healing products was gradually reduced.And the white substance at the crack mouth was mainly calcite CaCO_(3).The article proves that microbial induced calcium carbonate precipitation(MICP)technology can be effectively applied to the self-healing cracks in cement-based materials,which is beneficial for promoting the development and progress of microbial self-healing concrete.