Enhancing the interfacial compatibility and self-healing performance of microbial mortars by nano-SiO2-modified basalt fibers

Abstract

Fibers that enhance the self-healing ability of microbial mortar cracks have been widely studied. This study explored the impact of modified fibers on the self-healing performance and interfacial compatibility of microbial mortar by incorporating expanded perlite as a carrier of self-healing agents and basalt fibers modified with nano-SiO2. The effect of modified fibers on the mechanical properties of mortar was analyzed through compressive and flexural strength tests. The crack-healing effect of the specimens was evaluated using crack observation, UPV tests, and water absorption experiments, and the crack fillers were analyzed through SEM and XRD experiments to reveal the self-healing mechanism. The experimental results confirm that the nano-SiO2 loaded on the surface of the modified fibers exhibits Pozzolanic reactivity and can react with Ca2+ and OH− in the pore solution of the mortar to form secondary C-S-H on the fiber surface, which enhances the bonding ability between the fibers and the cement slurry, effectively improving the mechanical properties of the specimens. The rough surface of the modified fibers facilitates the deposition of calcite produced by microbes and hydration products, promoting the early-stage healing rate. Furthermore, due to the C-S-H shell on the surface of the modified fibers, the electronegativity of the fiber surface is improved, which is beneficial for bacterial adhesion and promotes the deposition of calcite, ultimately enhancing the self-healing capability.