Use of recycled concrete aggregate in concrete – a review

What is it about?

This document reviews the use of recycled concrete aggregate (RCA) in concrete production, emphasizing its potential to promote sustainability in the construction industry. With rising infrastructure demands and depletion of natural resources, recycling construction and demolition (C&D) waste into RCA is gaining attention as a viable solution. RCA, derived from C&D waste, can reduce CO₂ emissions by 15–20% and conserve up to 60% of limestone resources, contributing to more eco-friendly construction practices. The paper explores the properties of recycled aggregate concrete (RAC), noting that RCA typically exhibits lower quality than natural aggregates due to adhered mortar, which affects workability, water absorption, strength, and durability. Despite these limitations, various enhancement methods are discussed, such as mechanical processing, chemical treatments, and mineral admixtures, which can significantly improve RAC’s performance. An important finding is that RCA sourced from high-strength parent concrete (e.g., 60 MPa) can fully replace natural coarse aggregates without compromising quality. Innovative techniques like triple mixing and surface treatments using pozzolanic materials are also highlighted to boost RAC's mechanical and durability properties. The review concludes that, with appropriate treatment and mix design, RCA holds strong potential for use in structural concrete, offering a path toward greener and more sustainable construction.

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Photo by Marek Studzinski on Unsplash

Photo by Marek Studzinski on Unsplash

Why is it important?

The document discusses the importance of using recycled concrete aggregate (RCA) in concrete production. The key points regarding its importance are: 1. Environmental sustainability: Using RCA helps minimize the construction industry's environmental footprint by recycling construction and demolition (C&D) waste. 2. Resource conservation: It reduces pressure on natural resources by using recycled materials instead of virgin resources for concrete production. 3. Waste management: RCA provides a solution for the significant amount of C&D waste generated globally, which is often disposed of in landfills. 4. Emissions reduction: Using RCA in concrete can reduce CO2 emissions by 15%-20%. 5. Limestone conservation: It helps conserve 60% of limestone resources. 6. Economic benefits: In some cases, RAC (Recycled Aggregate Concrete) can be more cost-effective than concrete made with natural aggregates. These points highlight the environmental, economic, and resource management benefits of using recycled concrete aggregate in construction.