Development and performance evaluation of a composite-modified cold patch asphalt mortar and mixture for sustainable pavement maintenance

To overcome the challenges of high energy demand and weather constraints inherent in traditional Hot Mix Asphalt (HMA) in pavement crack sealing and pothole repair, this study proposes a novel composite cold patch asphalt mortar (CPAM) and cold patch asphalt mixture (CPAMix). By optimizing aggregate gradation and binder content, CPAM can be directly applied for crack sealing, while the addition of coarse aggregates enables its use as CAPMix for pothole repair. A composite-modified cold patch asphalt (CPA) was first developed using Styrene Butadiene Styrene (SBS) and one-component moisture-curing polyurethane, with the optimal formulation determined through orthogonal experimental design. The mechanical performance and microstructural development mechanisms of CPAM for crack repair were systematically evaluated using tensile and scanning electron microscopy (SEM) tests. Additionally, the road performance of CPAMix for pothole repair was assessed through Marshall stability tests, Wheel Tracking Tests (WTT), three-point bending tests and immersed Marshall tests. The results demonstrated that LB-CPAM exhibited superior mechanical and interfacial bonding properties. Moreover, LB-13 CPAMix demonstrated outstanding initial strength, formed strength, high-temperature stability, low-temperature crack resistance, and water stability, surpassing the technical requirements for conventional HMA. These findings provide a promising guidance for the development of environmentally friendly, high-performance materials for asphalt pavement crack and pothole repair.