Mechanical properties of concrete mixed with recycled powder produced from construction and demolition waste

Partial replacement of Portland cement with recycled powder (RP) obtained from construction and demolition (C&D) waste has been highlighted as a sustainable approach. This paper presents a comprehensive study to investigate mechanical properties and early-age cracking behavior of recycled powder concrete (RPC) made with two water to binder (w/b) ratios and different RP replacement percentages. RP is found to have relatively high fineness and considerable reactivity. Furthermore, the results indicate that mixes with RP have a higher hydration rate than cement mixes without RP. Up to 30% replacement of RP is found to have positive or minimal negative effect on mechanical properties of RPC. Whereas replacement percentages above 45% lead to considerable decrease in all mechanical properties investigated. Therefore, based on the results, RP replacement percentage in the range of 15%-30% is recommended. The addition of RP is found to adversely affect the concrete's workability and early-age cracking; and cracking control measures should be taken.