Effect of microbial repair materials based on sodium alginate modification on mortar crack repair

In response to the shortcomings of traditional concrete crack repair materials, a new generation of repair materials has been developed - a microbial repair material based on sodium alginate modification. The method adopts a brushing technique to fix the microorganisms on the cracks to be repaired so that they can deposit calcium carbonate in situ to repair the cracks. This paper carried out a study of the fundamental properties of the repair material, as well as studied the macroscopic morphology and surface water absorption of its specimens before and after repairing mortar cracks, and analyzed the material changes and microstructures of the repair products. The results showed that: (1) the CaCO3 content, water absorption ratio and heating shrinkage rate of the microbial repair material modified with sodium alginate were better than those of the repair material without microorganisms; (2) the microorganisms were fixed in the cracks on the surface of the mortar using the brushing technique with sodium alginate as the carrier and were able to adhere tightly to the cracks after only two repairs to produce repair products, which were mainly calcium alginate and calcium carbonate, and the surface water absorption rate was reduced by about 65% compared to that before the repair.