Life cycle assessment of concrete structures with reuse and recycling strategies: A novel framework and case study.

In the construction industry, reuse and recycling strategies help reducing waste, saving energy and cutting down emissions by converting construction and demolition (C&D) waste into resources. This study proposes a novel framework to guide the life cycle assessment (LCA) of concrete structures with reuse and recycling strategies. The material flow in recycling strategies is clarified explicitly. A new definition of degradation rate is introduced to set a nonlinear allocation rule for reusable components based on the durability feature of concrete structures. Reusable rate and replacement percentage are adopted to provide a convenient way to adjust the type and level of the strategies. As a result, a unified system boundary and corresponding indicator functions can be established for various strategies, combing the closed-loop analysis and the open-loop analysis. In the case study, design for deconstruction (DfD) and recycled aggregate concrete (RAC) are taken as examples of reuse and recycling strategies, respectively. With the proposed framework, LCA of various strategy combinations are conducted considering the global warming potential (GWP) and abiotic depletion potential (ADP) indicators. Results show that the maximal environmental benefit of DfD is 1.8-2.8 times compared to that of RAC. When adopting DfD and RAC simultaneously, the environmental benefit level of each strategy will decline, whereas the overall benefits will be increased. LCA with the proposed framework avoids some assumptions in conventional LCA and provides more reliable results for various strategy combinations.