Development and Performance Evaluation of Bacterial Concrete Using Bacillus Subtilis for Autonomous Crack Healing

Caracking is an inevitable phenomenon in concrete structures that significantly affects durability and service life by facilitating the ingress of aggressive agents. In recent years, self-healing concrete has emerged as a promising solution to address these challenges. This study investigates the mechanical performance, durability characteristics, and crack-healing efficiency of bacterial concrete incorporating Bacillus subtilis. Bacterial concentrations of 10⁶, 10⁷, and 10⁸ CFU/ml were introduced into M30 grade concrete. Compressive strength, split tensile strength, ultrasonic pulse velocity (UPV), water absorption, sorptivity, and rapid chloride permeability tests (RCPT) were conducted. Controlled cracks were induced, and healing was monitored over 7, 14, and 28 days. The results demonstrate that bacterial concrete exhibits superior strength, reduced permeability, and effective crack healing compared to conventional concrete. The mix containing 10⁸ CFU/ml showed optimum performance, achieving up to 90% crack-healing efficiency. The findings confirm that bacterial concrete is a sustainable and durable alternative for modern infrastructure applications.