Incorporation of recycled aggregates and silica fume in concrete: an environmental savior-a systematic review

Abstract

This review article has attempted to address the problems associated with river sand mining and the adverse impacts of CO2 emissions from the construction sector. The PRISMA framework employed a systematic literature review (SLR) methodology for the data extraction. The various strength parameters, such as relative compressive strength, relative splitting tensile strength, and relative flexural strength of concrete made from recycled aggregates (RAs) and silica fume (SF), were examined. The experimental results from various past studies have shown that 30% of RAs achieve a similar strength compared to concrete made by natural aggregates (NAs). At 50%, the compressive strength was merely reduced, and at 100%, a significant reduction in strength was seen. The positive variation in the strength was seen when SF incorporated from 5 to 20%. However, the best outcome in compressive strength was reported at a 10% ordinary Portland cement (OPC) replacement. The durability of concrete made by RAs was slightly lower, and SF-based concrete was higher than regular concrete. The sample calculations for China from (2011 to 2013) showed that by replacing 10% of OPC with SF, 3.96 × 107 tons of CO2 emission could be reduced, and by replacing 50% of river sand with recycled fine aggregate (RFA), 7.35 × 108 tons of river sand can be saved annually. It can be concluded from this review study that the combination of RFA and SF waste would be environmentally friendly in association with more sustainable concrete.

Keywords

• CO2 emission
• River sand mining
• Recycled aggregate concrete
• Silica fume-based concrete