Efficiency of Bacteria-Based Self-Healing Mechanism in Concrete

Abstract

Concrete is most widely used as an essential building material in the construction industry all over the globe. Concrete deteriorates over time, and cracks eventually form on its surface for many reasons, such as environmental surroundings and extra. This deterioration and cracks might lead to the ingress of water and chemicals that susceptible steel bars or reinforcements to corrosion. Since this deterioration is inevitable, maintenance and repair are also necessary. This process requires skilled labor and is cost-effective. Thus, researchers suggested alternative techniques to enhance concrete's mechanical properties and search for treatments to be applied to concrete's surface for healing and sealing the cracks by producing calcium carbonate precipitation. Therefore, self-healing concrete was introduced; this method is significant as it's proven environmentally friendly. This research aims to investigate the use of liquid bacteria incorporated in concrete mix and assess whether there would be improvements in the mechanical properties of the bacterial concrete compared to the conventional mix and an autogenous self-healing mix. Two different concentrations of an alkaliphile bacterium called Bacillus Subtilis were incorporated into the concrete mixes to test their ability to repair cracks by producing calcium carbonate and sealing them. This experiment showed a remarkable increase in bacterial concrete's compressive and tensile strengths. A visible partial crack sealing was also observed in specimens containing different concentrations of Bacillus Subtilis. Results also indicate that optimum results were obtained when the bacterial solution of concentration 108 cells/ml was incorporated, especially at early ages.