Self-healing abilities of cement mortars containing microorganisms produced in the process of sewage sludge treatment

Abstract

The enormous quantity of sewage water produced each day continues to present a serious challenge for its treatment and management. Sewage water is one of the most abundant sources of biomass, such as bacteria. Concrete, on the other hand, is the second most widely employed substance on the planet, after freshwater. Cracking of concrete is a major factor affecting the strength and durability of the material. The development of a crack pattern can contribute to increasing the permeability of concrete, which is typically associated with a significant decrease in its durability. Under specific circumstances, bio concrete is a self-healing biomaterial. Bacteria have the ability to precipitate calcite in concrete or form a layer of calcite precipitation, which plays a crucial role in the remediation of plastic shrinkage microcracks, thereby enhancing the structural integrity and durability of concrete over the long term. This paper summarises the study of investigating the possibility of using sewage water as a self-healing agent, using bacteria from different stages of treatment to heal cracks in concrete samples, and evaluating the effect of sewage water from different stages of treatment on fresh and hardened concrete properties. Based on the data collected from the experiments. Complete replacement of ordinary tap mixing water with sewage water from the Biological Reactor oxygen Zone achieved cracks healing of a crack width of 200 μm in less than 14 days without compromising the binder and mortar properties such setting time, slump value, compressive and flexural strength when compared to a reference sample made with tap mixing water.