SELF-HEALING CONCRETE INCORPORATING BACTERIAL ADDITIVES FOR STRENGTH AND CRACK RESISTANCE: A REVIEW

Abstract

Self-healing concrete incorporating bacterial additives represents a paradigm shift in sustainable construction materials. This technology employs microbial-induced calcium carbonate precipitation (MICP) to achieve autonomous crack repair, with bacterial strains such as Bacillus subtilis, Sporosarcina pasteurii, and Bacillus megaterium demonstrating significant healing efficacy across diverse environmental conditions [1]. Various encapsulation techniques, including microcapsules, coated granules, and vascular systems, enhance bacterial viability and healing performance, enabling bacterial concrete to achieve up to 95% crack sealing and over 90% strength regain [1]. This review synthesizes current knowledge on bacterial concrete mechanisms, material compositions, and performance characteristics. Ureolytic bacteria like Bacillus pasteurii/Sporosarcina pasteurii, Bacillus subtilis, and Bacillus megaterium possess the property of exciting urea when integrated with a calcium source, helping seal cracks through CaCO₃ precipitation [2]. At optimal concentrations (10⁴−10⁷ cfu/mL), select bacteria may increase compressive strength by up to 32% and achieve gains of 14–29% in flexural and tensile strength, with potential reductions up to 50% in permeability and 45–55% decrease in chloride ion ingress, though these represent upper performance ranges rather than typical outcomes [3]. Despite substantial improvements in mechanical properties and durability, challenges persist regarding cost, scalability, standardization, and long-term bacterial viability. This review identifies critical research gaps and outlines strategies for advancing bacterial concrete toward practical field application and sustainability objectives