Research on interfacial zone failure of asphalt mixture mixed with recycled aggregates

Construction and demolition wastes (CDW) is a complex mixture containing cement mortar and mineral aggregate, recycled aggregates (RA) are further prepared by CDW after the crushing process. Investigating the effect of RA on interfacial zone failure of asphalt mixture is beneficial to promote the utilization of CDW in pavement engineering. Firstly, RA without strengthening treatment was used to prepare recycled aggregate asphalt mixture (RAAM), then the physical and mechanical properties of RA and RAAM were studied using microstructure analysis and performance tests. To comprehensively understand the influence of RA percentage on interface damage, the interfacial zone in RAAM was classified into cement mortar interface and natural aggregate interface. Results show that the attached cement mortar of RA is a porous material and leads to a weak interface adhesion with asphalt mortar. The cement mortar interface presents greater porosity and lesser modulus compared with the natural aggregate interface. Increasing RA percentage causes more interface failure during deformation, and the damage of cement mortar and its interface with asphalt mortar are the primary resources of failure. According to numerical simulation for fracture processing, the influence of replacing natural aggregate with RA on energy consumption is obvious, and it increases the average stress value of the interface. This study shows that RA can be used as an effective alternative for natural aggregate after enhancing its attached cement mortar.

Automated summary

Studying the effect of recycled aggregates (RA) on the interfacial zone failure of asphalt mixture can enhance the utilization of construction and demolition wastes (CDW) in pavement engineering. Results show that increasing RA percentage causes more interface failure, with the damage of cement mortar and its interface with asphalt mortar being the primary resources of failure.