Effective utilization and recycling of mixed recycled aggregates for a greener environment

Both global warming issue and ozone layer depletion have triggered the awareness of the utilization of recycled materials in construction industry for a greener environment. The utilization and recycling of mixed recycled aggregates (MRA) comprising recycled fine aggregates (RFA) and recycled coarse aggregates (RCA) were explored for construction applications using the coupled Taguchi-RSM optimization approach. Under stringent durability requirements, 35% RCA combined with 6% RFA can be utilized while 70% RCA combined with 30% RFA under non-stringent conditions for non-structural applications. Our study also revealed large potential applications of pretreated mixed recycled aggregates in above-ground structural construction applications. Furthermore, review of literatures revealed presence of behavioral, technical, legal and market barriers which can be overcome through proposed measures. Our study also revealed a payback period of 3 years for recycling investments and revenue generation of HK$ 12 billion within the first ten years of operation and prevention of 20.9–50.1 × 10⁶ KgCO₂ equivalent emission annually. In order to achieve these benefits, a pragmatic, recycling-based closed-loop construction and demolition management approach is recommended to achieve a greener environment. Government should take active leading role towards CDW recycling through high-impact policy making and implementation.