Comparative Environmental Impacts of Recycled Concrete Aggregate and Manufactured Sand Production

Construction and demolition waste (CDW) management is essential for the sustainable development of a country. Recycled concrete aggregates (RCA) manufactured from CDW can replace a significant portion of natural aggregates in concrete as per various research studies conducted. Nowadays, various alternate waste materials are being utilised to minimise the environmental footprint of concrete. The manufactured sand (MS) is also one of the alternate materials being used in concrete production. There are significant studies available world-wide, which estimated associated environmental impacts of RCA; however, author could not find comparative study on environmental impact of RCA and manufactured sand (MS) production using optimization techniques in Indian perspective. Therefore, this study assessed the environmental impacts of producing 1-ton RCA from reclaimed concrete and MS from granite stone. Seven mid-point environmental impact (EI) categories of ReCePe method, i.e. global warming potential, human-toxicity potential, particulate matter formation potential, terrestrial acidification potential, freshwater eutrophication potential, photochemical ozone formation potential and resource use-fossil were calculated and interpreted. Analytic hierarchy process (AHP) optimization technique was used for calculating the weightage of EI categories. Hotspot and sensitivity analysis were performed to know the relevance and sensitivity of EI categories. As per the observation, CO2 emission and primary energy consumption in 1-ton RCA were 10% and 18.5% less than 1-ton MS. The suspended particulate matter and noise level in RCA were 25% higher and 9% lesser than MS. Transportation and crushing were the main contributors to EIs. This study may help in taking a calculative decision regarding utilization of RCA and MS as river sand replacement in concrete.