In situ disposal of crushed concrete waste as void fill material at UK nuclear sites: Leaching behavior and effect of pH on trace element release

•Stockpiled crushed concrete waste is weathered and partially carbonated.•Leaching controlled by carbonate and calcium silicate hydrate dissolution.•Waste has high acid buffering capacity but low alkaline buffering capacity.•Contaminant metal release occurs above pH 12 and below pH 5.•Crushed concrete is suitable for reuse as a fill material without further treatment.