Cutting-edge techniques and environmental insights in recycled concrete aggregate production: A comprehensive review
Ram Prasad Neupane, Ningombam Reena Devi, Thanongsak Imjai, Abhishek Rajput, Takafumi Noguchi
Abstract
The rapid growth of urban infrastructure has led to a substantial rise in construction and demolition waste (C&DW), causing environmental issues like overflowing landfills and depletion of natural resources. Recycled concrete aggregates (RCA) offer a sustainable alternative to natural aggregates (NA), helping reduce landfill use and energy consumption by up to 85 % and lowering CO 2 emissions by 90 %, providing significant environmental and economic benefits. However, untreated RCA exhibits lower strength and durability due to adhered mortar and impurities. This review delves into novel and advanced RCA treatment methods and production techniques that enhance RCA's properties. These methods achieve up to 42 % improvement in compressive strength and a 27 % reduction in water absorption. Researchers have found that impact crushers produce higher-quality aggregates compared to jaw or cone crushers. Treatments like acid washing and carbonation enhance particle density and reduce water absorption by 17.5 %. Recycled aggregate concrete (RAC) produced from treated RCA can reach 87 % of the compressive strength of natural aggregate concrete (NAC), with certain combined treatments achieving results close to NAC. Inconsistencies in RCA properties due to various treatments emphasise the need for standardised production and testing guidelines. This review underscores RCA's role in promoting sustainable construction and its potential to significantly mitigate CO 2 emissions, encouraging further research to refine these methods for long-term environmental gains.