Synergistic self-healing effect and mechanism of fiber and biological capsule on mortar cracks

In this paper, biological capsules were prepared with volcanic rock particles as bacterial carriers, while water glass and low alkaline sulphoaluminate cement were used as shell materials. The self-healing effect and mechanism of mortar samples prepared with Polyvinyl alcohol (PVA) fibers and biological capsules were studied. The results showed that the samples had the best crack-healing effect after adding PVA fibers and biological capsules. The cracks (<400 μm width) were completely healed. Calcite-type CaCO3 was identified as the primary healing product with irregular and square crystals. In addition, the formation rate of healing products was analyzed by measuring the changes in Ca2+ concentration and pH value in the curing solution. The three-dimensional morphology of healing products attached to the PVA fibers was obtained by laser scanning confocal microscope. Finally, the cementation mechanism between calcite and C-S-H was studied by molecular dynamics simulation.