Influence of bacterial biomineralization conditions on the microstructural characteristics of cement mortar

Abstract

Bacterial concrete is considered an effective self-healing material due to its capacity to repair damages such as cracks autonomously throughout microbially induced calcium carbonate precipitation (MICP). This study aimed to evaluate the direct incorporation of bacteria into mortar within the framework of concrete damage repairing technol-ogy. Sporosarcina pasteurii, a bacterium capable of surviving in alkaline conditions and inducing biomineralization by precipitating calcium carbonate, was selected for this purpose. Cement mortars with and without bacteria were prepared, and these samples were cured in different solutions to examine bacterial reactivity: a media solution for bacterial growth and calcium carbonate precipitation, a urea solution for calcium carbonate precipitation, and normal water. Mechanical properties and microstructural characteristics were investigated using various approaches. The out-comes revealed that the calcium carbonate precipitated by bacteria in cement mortar exhibited varying phases, such as calcite and vaterite, depending on the specific curing solutions employed. Particularly, the presence of properly precipitated calcium carbonate was found to significantly enhance the durability and mechanical properties of the cement mortar.