Hydrotalcite-pyroaurite solid solution in cement system...

Hydrotalcite-pyroaurite solid solutions, which are common minerals both in nature and in modern cementitious materials, hold significant potential for waste immobilization and cement properties yet remain insufficiently studied. In this work, we first synthesized a series of hydrotalcite (Mg₆Al₂(OH)₁₆CO₃·nH₂O) and pyroaurite (Mg₆Fe₂(OH)₁₆CO₃·nH₂O) solid solutions and conducted comprehensive characterizations. Synchrotron-based X-ray absorption spectroscopy was further employed to elucidate the molecular structure, while molecular simulations explored changes in charge density induced by Fe substitution. The results reveal that Fe substitution for Al reduces the thermal stability and induces structural changes. Specifically, the larger ionic radius of Fe³⁺ compared to Al³⁺ increases the unit cell parameters and elongates the FeO and FeMg distances in the local structure. Fe substitution also leads to localized positive charge accumulation within the layer. Additionally, thermodynamic parameters were obtained, and a solid solution model was established to supplement the existing thermodynamic database.

Read more: https://doi.org/10.1016/j.cemconres.2025.107976