An empirical study on the mechanical and durability characteristics of M50 grade high-strength bacterial concrete using Bacillus bacteria

Concrete is commonly utilised in construction. Curing strengthens and shrinks concrete. Reactive liquids enter concrete through shrinkage cracks. These fluids lower core pH, corroding reinforcing bars under ideal conditions. Therefore, concrete crack repair and structural integrity restoration methods must be developed. Currently, the use of synthetic polymers to repair environmentally detrimental cracks has prompted the advancement of biological therapy methods. These synthetic polymers affect the environment. The study seeks to improve concrete quality and mend cracks sustainably. In this study, Bacillus subtilis and Bacillus megaterium bacteria is used which synthesize calcium carbonate and seal small cracks. This bio-based concrete was found to enhance the mechanical strength and durability properties of M50 grade concrete, resulting in a high-strength bacterial concrete. Each bacteria have four concrete mixes like 15 ml, 30 ml, 45 ml, and 60 ml of bacteria, including one mix without bacteria. Mechanical and durability tests were performed on each combination at 7, 28, 56, and 90 days to determine its hardness. The concrete mixes without bacteria increased compressive strength by 6–11 MPa during 28–90 days. In contrast, bacterial concrete mixes rise from 10 to 16 MPa. The evaluation findings indicate a substantial enhancement in strength and durability of the concrete with bacterial mixes than concrete without bacteria. The scanning electron microscope images and Energy Dispersive Spectroscopy graphs demonstrated an increased density, as calcite carbonates filled the pores and sealed the cracks.