Research on long-term strength formation and performance evolution with curing in cold recycled asphalt mixture

This paper aims to study the long-term strength and performance evolution of cold recycled mixture with emulsified asphalt (CRME). The specimens of CRME were prepared and cured in the laboratory. The indirect tensile strength (ITS) was measured over curing time (7, 14, 40 days), considering the binder (emulsified asphalt and cement), the RAP properties and the compaction work. The asymptotic regression model was introduced to describe the strength evolution of CRME with curing time. The long-term evolution of the resistance of rutting and cracking, moisture stability and fatigue resistance were also investigated. The results indicate that the Michaelis-Menten model can effectively describes the performance evolution of CRME over time. The aged asphalt in RAP still has the bonding activity and can contribute to short-term strength formation and long-term strength growth of CRME under compaction and curing. But the aging degree of aged asphalt has a negative effect on the strength formation and growth of CRME. The emulsified asphalt provides CRME with greater strength and strength growth potential than cement. The dual effect of cement and emulsified asphalt is most pronounced in the short- and long-term strength evolution of CRME. The higher compaction power, especially in secondary compaction, is beneficial to the short- and long-term strength formation of CRME. The resistance of the mixture to rutting, cracking and fatigue also improves with increasing curing time. Nevertheless, the moisture stability is basically unchanged during the laboratory curing.