Experimental study on the principal factors influencing the effectiveness of microbial-induced calcium carbonate precipitation in asphalt concrete crack repair based on response surface methodology

This study investigates microbial-induced calcium carbonate precipitation (MICP) for asphalt concrete crack repair using response surface methodology. Key factors affecting unconfined compressive strength (UCS) enhancement were prioritized as Talbot index > crack depth > crack width. Optimal conditions (Talbot index 0.2, 0.5 mm width, 20 mm depth) maximized UCS improvement by 1.01 MPa and tensile strength by 0.11 MPa versus untreated samples. Ultrasonic pulse velocity increased 37.86%, while water absorption decreased 43.43%. Microscopic analysis identified 5-10 μm spherical calcium carbonate crystals forming mechanical bonds with asphalt particles, effectively filling cracks. The results demonstrate MICP’s potential as an eco-friendly solution for pavement rehabilitation, particularly in low-gradation, narrow/shallow cracks. Performance metrics and microstructural evidence collectively validate the technology’s efficacy in creating cohesive crack-sealing structures. These findings provide critical insights for optimizing MICP implementation in sustainable roadway maintenance strategies.