Powder wastes from concrete recycling as a sustainable source of calcium carbonate mineral admixture

Carbonation technology applied to cement-based materials from concrete recycling has been investigated as a promising approach to achieve carbon neutrality and to reintroduce these wastes into concrete’s life cycle. In this research, carbon uptake potential of powder wastes from concrete recycling (PWCR) was evaluated. Samples were obtained from recycled concrete aggregate production – Recycled Concrete Aggregate Powder (RCAP), and from dewatered wash-out of returned fresh concrete – Concrete Slurry Waste (CSW). PWCR were used as mineral admixture replacing the sand, and it was observed that RCAP was naturally a fine powder with high CaCO₃ content, resulting in good mortar performance. In contrast, the coarse powder and with low CaCO₃ content CSW reduced mortar’s performance. But with accelerated carbonation, carbonated CSW (CCSW) showed satisfactory performance when used in mortar. Therefore, there is high a potential to explore PWCR as a sustainable source of CaCO₃ to be reused as a mineral admixture.