Optimized treatment of recycled construction and demolition waste in developing sustainable ultra-high performance concrete

Abstract This paper addresses an effective way to apply recycled construction and demolition waste (C&D waste) in developing ultra-high performance concrete (UHPC). To be specific, the modified Andreasen & Andersen (A&A) particle packing model is employed firstly to achieve a dense packed structure of UHPC. Secondly, C&D waste is used to replace cement and aggregate synchronously in order to minimize negative effect on the dense packing structure aforementioned. After that, the impact of replacing cement and aggregate by C&D waste on the properties of UHPC is assessed. Experimental results reveal that benefits including reduction of early heat accumulation and auto-shrinkage, low energy consumption are generated when replacing up to 50% of cement and 19% of fine aggregate by C&D waste. In this case, a comparable compressive strength can be obtained. Additionally, the scanning electron microscope (SEM) analysis results also highlight improved microstructure owing to the addition of this solid waste. Conclusively, recycling of C&D waste as filling material in developing UHPC provides a promising view to develop a sustainable cement based material with advanced properties.