Optimization of Mechanical and Durability Performance of Bacterial Concrete Using Taguchi Method

Crack formation in cement concrete adversely affects durability by allowing the ingress of moisture and aggressive agents. Microbially Induced Calcium Carbonate Precipitation (MICP) has emerged as a promising technique to enhance concrete performance. This study investigates the influence of Bacillus subtilis on the mechanical and durability properties of concrete. Concrete mixes with bacterial concentrations ranging from 10¹ to 10⁸ CFU/mL were prepared and evaluated at multiple curing periods. Mechanical properties were assessed through compressive, split tensile, and flexural strength tests, while durability was evaluated using Ultrasonic Pulse Velocity (UPV) and Rapid Chloride Penetration Test (RCPT). Results indicated a maximum increase of 30.10% in compressive strength, improvement in UPV values up to 16.70%, and significant reduction in chloride permeability. Microstructural analysis using SEM and XRD revealed pore refinement and matrix densification due to bacterial activity. A Taguchi-based optimization approach was employed to identify optimal parameters, indicating 10⁵ CFU/mL as the optimum bacterial concentration. The observed improvements are attributed to combined mechanisms of pore filling and microstructural enhancement rather than solely calcite precipitation. This study focuses on strength and durability enhancement providing a systematic framework for optimizing bacterial concrete.