Development of sustainable alkali-activated slag bricks with high content of carbonated recycled concrete fines: Strength, microstructure and environmental benefit

This research presents a novel method of recycling construction waste while capturing CO2 through the formation of mineral carbon. The technology uses carbonated recycled concrete fines (CRCF) as the primary raw material to produce sustainable, high-performance alkali bricks with high replacement rates. Firstly, a general assessment of the physical and chemical properties of CRCF was carried out, which revealed the formation of silica gel encapsulating the surface of CRCF during carbonation. Subsequently, alkali bricks were prepared utilizing CRCF. The study investigated the impact of various mix proportions, water-to-cement ratios, and manufacturing process parameters on brick strength. Additionally, an in-depth analysis of reaction products and brick microstructures was carried out. The results showed that the bricks produced from CRCF were stronger than those from RCF, indicating enhanced reactivity after carbonation. Finally, an analysis demonstrated that utilizing RCF from construction waste can significantly reduce carbon dioxide emissions, thereby mitigating the environmental impact associated with cement production.