Investigation of Mechanical Strength Recovery and Self-Healing Efficiency of Bio-Mineralized Sustainable Concrete

The current research investigates the self-healing capability of concrete containing steel slag aggregates (SS) by incorporating bacteria into fine aggregates and SS. Using vacuum impregnation, vegetative cells of the Bacillus subtilis bacterium are introduced to enhance the efficiency of the concrete healing mechanism. Concrete specimens are subjected to cracking up to 85% of their strength, followed by evaluations of crack healing widths and strength recovery over different curing periods. The findings of this study revealed that SS serves as an effective medium for bacterial growth, achieving crack healing widths of 0.65 mm and a 74.2% recovery in the strength index. Bacteria immobilized by combining 50% fine aggregates with SS demonstrated optimal healing efficiency, showing a crack width of 1.023 mm at early pre-crack stages and 0.56 mm at later stages. The direct use and combined integration of 50% fine aggregates with SS resulted in compressive strength improvements of 4.3% and 7.8%, respectively. The mix containing 50% fine aggregates and SS exhibited the highest split-tensile strength, with a 41.67% increase compared to the control mix.