Development of a novel compressed tablet-based bacterial agent for self-healing cementitious material

A novel bacterial carrier consisting of microcrystalline cellulose (MCC) tablets was developed to encapsulate spores and has 3.0 +/- 0.5 x 10(11) spores per dried gram, which could improve the self-healing efficiency of bacterial agents. The alkaline-resistant and spore-forming bacteria Lysinibacillus boronitolerans YS11 and Bacillus miscanthi AK13 could fill microcracks with precipitated calcium carbonate in harsh cement conditions. The MICP-capable bacteria in the tablets cured the microcracks within 7 days. The calcium carbonate on the cracks was identified via scanning electron microscopy and X-ray diffractometry, validating the MICP performance and bacterial viability. Constituting only 3% of the cement mass, the MCC-tablet allowed repairing of micro-cracks. The water permeability of mortar specimens mixed with MCC tablets steadily reduced with increasing curing ages, with crack repair rates of up to 91.1% within 28 days. Our study proved that the MCC tablets developed herein are effective carriers of bacterial spores and could thus be used for the development of self-healing cementitious material.