Effect of Addition Amount of Microbial Self-Repairing Material on Anti-Cracking Performance of Concrete

Although microbial self-healing concrete technology has been widely studied, limited attention has been paid to the effect of the dosage of microbial self-healing materials on concrete crack repair performance. To address this, this study investigates the influence of the dosage of microbial self-healing materials on the crack repair performance of concrete using planar thin-plate specimens. The results are summarized as follows: (1) Increasing the dosage of microbial self-healing materials effectively delays the initial cracking time of concrete specimens. When the dosage levels were 10%, 20%, and 30%, the initial cracking time was prolonged by 50%, 65%, and 70%, respectively, compared with the blank group without microbial addition. (2) After 28 d of water spraying and coating curing, the total crack area of concrete decreased significantly compared with that at the early age (1 d). For dosages of 0%, 10%, 20%, and 30% of microbial self-healing materials, the total crack area per unit surface area decreased by 12.2%, 21.9%, 22.7%, and 31.8%, respectively, compared with the initial stage. (3) Through X-ray diffraction (XRD), thermogravimetric analysis (TG/DTG), and morphological characterization, the presence of microbial mineralization products, including calcite and vaterite, on the concrete crack surfaces was confirmed.