Cleaner production of the precast concrete industry: comparative life cycle analysis of concrete using recycled aggregates from crushed precast rejects

AbstractThe in-plant use of recycled aggregate concrete derived from precast rejects (termed PRAC herein) can promote a circular economy in the precast industry. However, the environmental implications associated with this practice remain poorly understood. A refined life cycle assessment (LCA) model was therefore developed to highlight the environmental benefits of using PRAC compared to natural aggregate concrete and conventional recycled aggregate concrete. Some key factors influencing PRAC's environmental performance were also examined. The results indicate that PRAC exhibits around 15% lower energy consumption and carbon dioxide emissions compared to other recycled materials. This reduction is attributed to the favourable quality of PRAC and the elimination of long-distance transport. However, emissions allocation and raw material prices play significant roles in determining the overall environmental impact of PRAC. The equivalent mortar volume mixing method is best suited for PRAC production, as it saves energy, reduces emissions, and maintains similar mechanical properties. Nevertheless, the high-temperature curing, which is often necessary in a precast factory setting, can be energy-intensive and thus diminishes the eco-friendliness of PRAC. Overall, the findings support the use of precast rework as recycled aggregate for cleaner production in the precast industry.Keywords: Recycled aggregate concreteprecast rejectsfly ashhigh-temperature curingemissions allocationcasting methods Authors contributionYong Yu: Conceptualization, Methodology, Investigation, Formal analysis, Writing – Original draft, Funding acquisition. Fernando Pacheco-Torgal: Conceptualization, Investigation, Writing – Reviewing and Editing. Xin-Yu Zhao: Conceptualization, Methodology, Investigation, Formal analysis, Writing – Reviewing and Editing, Funding acquisition, Supervision. Xiaolu Wang: Conceptualization, Investigation, Writing – Reviewing and Editing.Data availability statementThe LCA models supporting the findings of this study are available from the corresponding author by reasonable request.Disclosure statementNo potential conflict of interest was reported by the authors.Additional informationFundingThe authors would like to acknowledge the research grants from China's Natural Science Foundation (51978280, 52008108), Guangdong Basic and Applied Basic Research Foundation (2019A1515110481, 2019A1515110050) and Guangdong Provincial Key Laboratory of Modern Civil Engineering Technology (2021B1212040003).