Enhancing the high-temperature resistance of self-healing bio-cementitious composites using tea waste as a bacterial carrier

Abstract

Bacterial composites exhibit advanced self-healing capabilities; however, their effectiveness is often constrained by production processes and environmental conditions. To enhance bacterial viability, protective carriers are required, with natural fibers recently utilized for this purpose. Fiber reinforcement has been shown to improve self-healing efficiency by limiting crack propagation. This study investigates the potential of tea waste as a bacterial carrier in cementitious composites. Bacillus megaterium spores were absorbed into tea waste and incorporated into mortar specimens at varying concentrations. The durability of bacterial composites under high-temperature exposure, a critical yet underexplored aspect, was also evaluated. Mortar specimens containing bacterial tea waste were subjected to different high-temperature conditions in both undamaged and pre-cracked states, followed by compressive strength assessments. Post-exposure microstructural changes were analysed via scanning electron microscopy (SEM). The findings demonstrated that tea waste effectively functioned as a bacterial carrier, exhibiting behaviour comparable to natural fibers. Additionally, it contributed to enhanced residual strength by mitigating thermal stress and promoting calcite precipitation, facilitating damage repair. These results highlight the potential of tea waste as a sustainable and effective medium for improving the durability of bacterial composites against high-temperature effects.