The Impact of Recycled Concrete Aggregate on the Stiffness, Fatigue, and Low-Temperature Performance of Asphalt Mixtures for Road Construction

Abstract

The need for road (re)construction materials is constantly growing. At the same time, there is a limited quantity of new, high-quality materials available and a buildup of secondary/recycled construction materials. One possible solution may be the use of recycled concrete aggregate (RCA) in asphalt mixtures instead of natural aggregate (NA), which also promotes economic and environmental sustainability. The potential use of fine and coarse RCA in road asphalt mixtures is analyzed in this work. Nine asphalt mixtures were tested for base course layers, where RCA was used as a NA substitute. The impact of the quantity of RCA (up to 45% by mass) on the resulting physical and mechanical properties of asphalt mixtures was investigated, and consequently compared with the properties of a reference control mixture produced with NA only. Results reveal that the addition of RCA requires higher bitumen in comparison to the control mixture (up to 1%). Consequently, mixtures with RCA had 15-20% lower stiffness and up to 26% higher critical fatigue strain value (E6). Although RCA mixtures contained more bitumen, their low-temperature resistance was slightly inferior compared with the control mixture (failure temperatures were up to 4.3 C higher). In conclusion, asphalt mixtures with up to 45% RCA can be used without substantially reducing performance.