To improve its resource utilization, this study prepares autoclaved aerated concrete (AAC) by partially replacing river sand with copper tailings (CT), with a focus on the effects of CT specific surface area and calcium-to-silicon (Ca/Si) ratio on performance of products. Results showed that increasing the CT specific surface area raised bulk density, whereas compressive strength first increased and then decreased. Moreover, increasing the Ca/Si ratio caused bulk density to first decrease and then increase, whereas compressive strength followed an inverse trend. Optimal performance was achieved at a specific surface area of 235.0 m2/kg and a Ca/Si ratio of 0.70, with a mix ratio of 29.4% CT, 29.4% river sand, 21.2% lime, 18.2% cement, and 2.0% gypsum, and a water-to-solid ratio of 0.65. The resulting AAC exhibited a bulk density of 597.0 kg/m3, compressive strength of 3.82 MPa, and thermal conductivity of 0.144 W/(m·K), meeting the B06 A3.5 grade requirements of the current Chinese standard. Microstructural analysis identified interconnected tobermorite as the main hydration product in AAC. Whereas the specific surface area of CT had a minimal impact on hydration products, higher Ca/Si ratios increased the quantity of needlelike tobermorite. The findings indicate that CT can serve as a high-quality siliceous material for AAC production, offering new pathways for large-scale resource utilization and the development of sustainable building materials.
Hong et al. (Sat,) studied this question.