The feasibility of using copper slag in asphalt mixtures for base and surface layers based on laboratory results

•Small amounts (15%) of copper slag (CS) do not change optimal binder content.•The addition of 30% CS has almost no impact on mixture properties.•The coarse CS fraction reduces rutting resistance whereas the fine fraction reduces cracking resistance.•Leachates do not contain heavy metals.•CS has high potential to be used as an alternative to virgin aggregate in asphalt mixtures.