Investigation of the use of Bacillus subtilis bacteria in the repair of self-healing concretes

Small cracks in concrete may turn into large cracks over time, reducing the useful life of concrete structures. Therefore, the rate of growth and expansion of cracks should be limited. Repairing cracks in concrete is one of the effective ways to prevent the spread of cracks. Therefore, from the past until now, different methods for repairing cracks created on concrete due to different factors have been studied and compared. This study presents a biological method to improve the self-healing effect of concrete beams by the microbial activity of Bacillus subtilis. In this study, self-healing begins with the injection of Bacillus bacteria through an insulin syringe into the crack. For this purpose, 6 concrete beams with dimensions of 15 × 15 × 120 cm were made and the self-healing property by creating cracks by applying static torsional load was evaluated. In the end, according to the final torsional anchor of the beams, this result was obtained. The beam repaired with this method has increased the torsional capacity of the original control sample by 93.13% and the torsional capacity of the cracked beam has increased 7.6 times.