Bacteria based self-healing of cement mortars loaded at different levels and exposed to high temperature

Abstract

Structures are exposed to various external effects and loads throughout their service life. Such a case then results in failure at a load lower than the design compressive strength. Although there is a cement-based healing system for repairing these damages, it is often insufficient. Therefore, a more effective autonomous healing system is needed, and microbial-induced calcite precipitation (MICP) was most of the time experimented with for this purpose. In this study, bacterial mortar samples were produced and loaded at different levels of their ultimate compressive stress. The effects of the loads were determined, and the effectiveness of bacterial treatments was also investigated. Crack healing, compressive strength, water absorption, ultrasonic pulse velocity (UPV), and high temperature effect experiments were conducted. In bacterial mortar samples, the MICP mechanism repaired about 3.5 times larger cracks than the control samples. While the treatment of cracks and damage observed at 90% and 100% loading levels were highly limited thanks to the autogenous system, some properties of bacterial mortars improved as the loading level increased. It was observed that the MICP mechanism was more effective, especially in damaged samples with high load levels. In addition, bacterial mortars demonstrated more advanced physical, mechanical, and durability properties at each loading level.