Improving properties of Engineered Cementitious Composite (ECC) using Bacillus subtilis immobilized in silica gel

This study investigates the impact of incorporating Bacillus subtilis immobilized in silica gel (BS+SG) on various properties of Engineered Cementitious Composites (ECC). Silica gel serves as the immobilization medium to sustain bacterial viability in the challenging environment of ECC mixtures. The study explores bacterial content ranging from 5 % to 15 % of water content. Results reveal a significant enhancement in compressive strength for ECC with 5–15 % BS+SG, showing increases of 11.9–18.8 % at 28 days of water curing as compared to ECC without bacteria. This improvement becomes more pronounced at 56 days, attributed to silica gel's protective role in preserving bacterial activity, leading to calcite production that effectively fills pores during extended curing. The positive impact extends to tensile strength and strain capacity. Additionally, BS+SG contributes to reduced porosity and water absorption even after prolonged curing, thus enhancing the durability of ECC. This study highlights the potential of BS+SG in advancing the properties of ECC, with emphasis on its role in improving compressive strength, strain capacity, and durability.