Discrepancies in life cycle assessment applied to concrete waste recycling: A structured review

Concrete waste recycling has been considered an efficient way to reduce environmental impacts in the end-of-life treatment of construction waste materials compared to traditional landfilling. Developing advanced and sustainable technologies in recycling processes grows with significance for enhancing the performance of recycled products. However, there is still a lack of systematic analysis and comparison of the studies adopting life cycle assessment (LCA) to examine environmental potentials of varied concrete waste recycling processes. This paper identifies up-to-date enhancement techniques for recycling concrete waste and provides a comprehensive analysis of selected cases that evaluated environmental impacts of recycling processes with LCA approaches. A total of 22 representative case studies were compared systematically using the key parameters involved in four major steps of LCA framework. Critical issues were identified from previous research studies. It is of great importance to standardize the rules for determining system boundaries and functional units, validate foreground and background inventory databases, and improve the utilization of combined uncertainty and sensitivity analysis. A specialized LCA computational tool for concrete waste recycling is in high demand for industrial decision-makers and practitioners. The proposed system boundaries of advanced recycling technologies and conceptual framework of platform development highlight potential directions for future research.