Case Studies in Construction Materials (Dec 2024)
Enhancing concrete crack healing: Revealing the synergistic impacts of multicomponent microbial repair systems
Abstract
Small cracks in concrete can develop into larger cracks, reducing the service life of concrete structures. Therefore, the early prevention of fine crack progression is crucial. In this study, a multimicrobial system composed of Bacillus megaterium and Saccharomyces cerevisiae was used to repair concrete cracks, and its repair efficiency was evaluated through fracture healing observations, permeability tests, acoustic time value detection, and unconfined compressive strength tests. Additionally, scanning electron microscopy, energy dispersion spectroscopy, X-ray diffraction, and Fourier-transform infrared spectroscopy were used to analyze the concrete repair mechanism of the multicomponent microbial system. The results showed that when the ratio of S. cerevisiae to B. megaterium in the microbial system was 30 %:70 %, the calcium carbonate (CaCO3) yield increased by 10 %, and the mineralization deposition effect was optimal. Under the synergistic action of the two microorganisms, fracture healing proceeded quickly and the pore structure within the fracture became denser, significantly improving the permeability and strength repair rates of the sample and reducing the pulse velocity. For cracks 1.5 mm in width, the permeability and strength repair rates were 63 % and 35.12 %, respectively. The pulse velocity was reduced from 140 µs to 65 µs. The crack filler is mainly composed of CaCO3 crystals 5–10 µm in size, and the total calcium content of the multicomponent repair system was as high as 39.5 %, which was significantly higher than that of the single component repair system (36.1 %). The results indicate that the multicomponent microbial repair system maintains a higher calcium precipitation activity in a high-strength alkaline concrete environment and produces denser CaCO3 deposits, indicating good repair ability. These repair properties improve the overall performance of concrete. This study confirms the strong potential of multimicrobial systems for efficient, cost-effective, and environmentally-friendly concrete crack repair.
