Spray air leakage plugging is one of the effective means to prevent coal spontaneous combustion.Aiming at the drawbacks of high brittleness,easy cracking,and poor air leakage plugging effectiveness of traditional cement-based spraying air plugging material,bio-logical capsule,mineral capsule and bio-mineral-fiber synergistic self-healing material were developed with microorganisms and crystal-line minerals as self-healing agents.The influence of different curing humidity and curing time on the self-healing ability of material cracks was studied.The results showed that when the curing humidity was 100%,and the curing time was 35 days,the biological and min-eral capsules could completely heal the cracks,with a maximum healing width of 1260 μm.Scanning electron microscopy(SEM)and en-ergy dispersive X-ray spectroscopy(EDS)were used to investigate the crystal structure and elemental composition of the healing products in the crack area of self-healing material.It was found that the healing products at the crack were spherical magnesite,petal-shaped hydro-magnesite,and a large amount of spherical calcite produced by bacterial mineralization,which to some extent played a role in sealing the crack.EDS analysis confirmed that the healing products were MgCO3 and CaCO3.When the curing humidity was 100%,the material had the highest air leakage plugging rate(97.15%),which was 73.62%higher than the control group samples under the same curing conditions.Finally,self-healing material was used for spraying and plugging air leakage along the coal pillar,and the results showed that no obvious cracks were found within 6 months.Compared with traditional cement mortar,self-healing material has a longer service life and better pre-vention effect.
spray air leakage plugging materialcoal spontaneous combustioncrack repairhealing agentmicroorganismcrystalline minerals