Wijayasundara Mayuri, Mendis Priyan, Crawford Robert H
The University of Melbourne, Parkville, VIC 3000, Australia.
Waste Manag. 2018 Aug;78:279-291. doi: 10.1016/j.wasman.2018.02.042. Epub 2018 Jun 7.
Concrete waste (CW) either reaches landfill with mixed waste or crushed to produce crushed concrete (CC) used as a road-base product in Australia. The coarse portion of CC, referred to as recycled concrete aggregate (RCA) has the potential to be used as an aggregate in structural concrete replacing natural aggregate (NA). The environmental performance of RAC has been studied in comparison to NAC, in terms of direct environmental implications (DEI) concerning the processes in the production chain of these products. However, when replacement at industry level is considered, the implications go beyond the DEI, and affect a series of other products/processes within a system boundary, referred to as indirect environmental implications (IEI). This paper quantifies the key IEI associated with the use of RCA in structural concrete and evaluates the external costs and benefits associated with it using economic evaluation methods. The net benefit associated with the avoidance of landfill of CW, extraction of NA, and transportation of waste and by-products are the major externalities identified and quantified in this paper. Evaluation of these suggest that there is a significant net benefit ranging from 9% to 28% of the price of natural aggregate concrete (NAC) with the production of recycled aggregate concrete (RAC), for RCA replacement rates between 30% and 100%.
混凝土废料（CW）要么与混合废料一起运往垃圾填埋场，要么被粉碎以生产碎混凝土（CC），在澳大利亚用作道路基层材料。CC的粗颗粒部分，即再生混凝土骨料（RCA），有潜力用作结构混凝土中的骨料，替代天然骨料（NA）。与天然骨料混凝土（NAC）相比，已对再生骨料混凝土（RAC）的环境绩效进行了研究，涉及这些产品生产链过程中的直接环境影响（DEI）。然而，在考虑行业层面的替代时，其影响超出了直接环境影响，会影响系统边界内的一系列其他产品/过程，即间接环境影响（IEI）。本文对与在结构混凝土中使用RCA相关的关键间接环境影响进行了量化，并使用经济评估方法评估了与之相关的外部成本和效益。避免CW填埋、NA开采以及废物和副产品运输所带来的净效益是本文确定和量化的主要外部效益。对这些的评估表明，对于30%至100%的RCA替代率，生产再生骨料混凝土（RAC）会带来显著的净效益，占天然骨料混凝土（NAC）价格的9%至28%。
