A review of life cycle assessment of recycled aggregate concrete

Abstract

Abstract Recycled aggregate has emerged expecting to address raw materials shortage in construction sector by converting waste concrete into resource. Many researchers adopted life cycle assessment (LCA) to evaluate and compare environmental impact of recycled aggregate concrete (RAC) and natural aggregate concrete (NAC). However, there are numbers of problems in applying the LCA in RAC, a unified treatment of the subject is still lacking. By reviewing existing corresponding literature, this paper identified the existing problems of applying the LCA method in RAC from 5 aspects, including mixture design method, selection of functional units, allocation of inventory, CO2 uptake during the life cycle of concrete and transport distance of recycled aggregate. Review results indicate that when analyzing the environmental impact of RAC by LCA, a clear indication of the mixture design methods of RAC should be given at first. Second, a benchmark method to define the functional unit of the LCA of RAC is urgently needed to make different LCA studies comparable. A method that combining the effect of quality, mass and market price on the allocation procedure of recycled aggregate should be further investigated. Besides, ignoring CO2 uptake in the use stage of RAC will lead to an overestimated CO2 emission of RAC. In addition, a critical distance for recycled aggregate is existed when comparing the environmental impact between NAC and RAC. At last, some contents of recycled aggregate concrete for further research have been proposed.