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

Abstract

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.

Highlights:

• The crack healing mechanism of fibers and biological healing agents was studied.

• The relationship between ion concentration, pH and crack healing was clarified.

• The cementation mechanism between cracks and mineralized products was revealed.

Keywords:

• Biological capsule
• PVA fiber
• self-healing
• synergistic mechanism
• molecular dynamics simulation

Disclosure statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Data availability statement

Data will be made available on request.

Additional information

Funding

This work was supported by the National Natural Science Foundation of China [42077444, 52274217, 52274216, 52304242, and 42307585]; the ‘Elite Plan’ of Shandong University of Science and Technology [22-003 and 22-013]; the Shandong Natural Science Outstanding Youth Fund [ZR2021JQ19]; the Shandong Province Natural Science Foundation [ZR2023QE042, and ZR2023QE013]; Qingdao Natural Science Foundation [2321101-zyyd-jch].