The hydration behavior and foaming mechanism of foamed concrete prepared by substantial amounts of phosphate tailings

A novel approach to prepare foam concrete (PFC) with lightweight, high-strength and thermal insulating was proposed using substantial amounts of phosphorus tailings (PT) and cement as raw materials, and hydrogen peroxide as in-situ pore formation agent. The effects of PT incorporation on the hydration process and physical properties of PFC were investigated. Results showed that PT significantly reduced the dry density and thermal conductivity of PFC, but excessive PT hindered strength development. Optimal performance was achieved at 60 wt% PT incorporation, with a dry density of 852 kg/m³ , thermal conductivity of 0.156 W/(m·K), and compressive strength of 4.71 MPa, meeting relevant standards (TG/T266–2011, A09, C4). The addition of PT promoted calcite formation in PFC while had negligible impact on the types of primary hydration products. High content of PT altered the phase composition and loosened the network structure of hydrated products, limiting strength development. A 5 % addition of PT accelerated hydration by providing extra nucleation sites, improving compressive strength. PT also facilitated gas accumulation and pore formation, increasing porosity and enhancing thermal insulation. This study provides a practical strategy for designing high-performance foam concrete with substantial amounts of solid waste.