Study on frost resistance and life prediction of microbial self-healing concrete based on expanded perlite as carrier

Microbial Induced Carbonate Precipitation (MICP) enables concrete to self-diagnose and self-heal cracks, using microbial self-healing agents based on expanded perlite as a carrier in order to cope with concrete deterioration during freeze-thaw cycles. In this paper, the microbial self-healing agents were formed by adsorption of budding microorganisms inside expanded perlite, so that the mechanical, freeze-thaw and self-healing properties of microbial self-healing concretes with different strength grades and self-healing agent mixes could be systematically investigated. The results of the study showed that the bio budding technique was able to retain microbial activity during freeze-thaw cycling, and secondary budding activity after freeze-thaw cycling was able to reach 92.3 % at 96.1 % budding conversion rate. The freeze-thaw resistance of concrete was improved by the addition of microbial self-healing agents with expanded perlite as the carrier, and the freezing resistance showed an initial increase and then a decrease with the increase in the dosage of self-healing agents. The higher the strength grade of the concrete, the higher the optimum dosage of microbial self-healing agents, and at a strength grade of C60, the addition of 1 m3/m3 of microbial self-healing agents resulted in a maximum number of freeze-thaw cycles of 700 compared to the control of only 150. In addition to this the freeze-thaw cycling effect resulted in a decreasing trend in the crack healing rate, with maximum healing widths decreasing by 14.6 %, 23.9 %, 11.6 % and 15.2 % for the groups of strength grades C30, C40, C50 and C60, respectively. Therefore, in the application process in cold regions, in order to make concrete with high resistance to freezing and thawing and self-healing effect, and to avoid adverse effects on its mechanical properties, higher strength grade concrete should be used so as to ensure the maximum mixing amount of microbial self-healing agents. •Evaluation of the spore-producing properties of Sporosarcina Pasteurii and characteristics of spore germination.•Evaluation of microbial self-healing concrete for freeze-thaw performance.•Evaluation of self-healing properties of microbial self-healing concrete after freeze-thaw cycles.•Prediction of the service life of microbial self-healing concrete in freeze-thaw environments based on Weibull distribution.