The role of P2O5 on the stability of β-C2S in AOD slag based on the improvement of hydration activity

Abstract

The original AOD slag in the cold state contained more than 50 wt% low-hydration activity γ-C2S, which significantly affects the hydration activity. Therefore, the effect of the typical crystal stabilizer P2O5 on the formation of a new phase and the enhancement in the mass fraction of high hydration activity β-C2S in AOD slag were studied, and the internal factors that controlled the doping preference and influenced the hydration activity of the crystal stabilizer P2O5 were revealed. When the addition of P2O5 was 0.6 wt%, the mass fraction of β-C2S in AOD slag was increased by 50.8 wt%. The P5+ and its oxide P2O5 entered the lattice of C2S in solid solution, causing lattice distortion. After P doping, the charge energies of the Ca, Si and O atoms shifted toward the low energy direction by approximately 5 eV, which increased the stability of the electronic structure. In addition, P doping changed the delocalization of the CBM in the pure phase, partially located the LDOS of the VBM and CBM, and increased the numbers of nucleophilic and electrophilic attack sites, thus improving the hydration activity of β-C2S.