Laboratory study on the use of copper slag and RAP in WMA pavements

Abstract

This paper presents the results of an experimental investigation carried out on warm mix asphalt (WMA) incorporated with copper slag (CS) and reclaimed asphalt pavement (RAP) material. Both CS and RAP are considered as waste materials and cause a lot of environmental problems. Their use in asphalt pavements will solve the landfill problems associated with them. Also, to save energy and reduce carbon emissions, WMA technology was adopted in this study. A total of nine combinations of warm mixes were prepared with varying proportions of CS (0–15%) and RAP (0–30%). The use of CS improved Marshall stability, indirect tensile strength, and tensile strength ratio. The introduction of CS and RAP produced a balanced mix as CS improved mechanical properties due to high angularity, density, and lime content. In contrast, RAP decreased these properties except the Marshall quotient and resilient modulus. All the RAP–CS WMA mixes satisfied the minimum value of stability (9 kN) as required for dense bituminous macadam. Furthermore, it was concluded that the mechanical properties of RAP–CS WMA mixes decreased with each freeze–thaw (F–T) cycle. The CS-incorporated mixes showed better resistance against F–T cycles.