Bioinspired and biomineralized magnesium oxychloride cement with enhanced compressive strength and water resistance

High CO₂ emissions during the production process of ordinary Portland cement (OPC) promoted greener-cement development, wherein the application of magnesium oxychloride cement (MOC) can add value to waste in potash industry and reduce environmental hazards. However, its application was restricted by its inferior water resistance. It's a challenge to remarkably increase both the compressive strength and water resistance of MOC. Herein, we demonstrate that cornstarch/sodium polyacrylate (PAAS) MOC composites exhibit increased compressive strength and water resistance. Moreover, the biomineralization process encourages the growth and alignment of phase 5 crystals by a cornstarch template with hydroxyl groups, thus enhancing the compressive strength of MOC. The chelation of magnesium ions and the transformation of phase 5 crystal structure by PAAS can significantly enhance the water resistance of MOC. This composite exhibits a 21.0% increase in compressive strength, and the softening coefficient is also increased from 0.48 to 0.81 in comparison with unmodified-MOC. Meanwhile, the hydrogen bonds between cornstarch and elemental Cl obviously decrease the efflorescence phenomena of the MOC. This MOC composite with a markedly increased compressive strength and water resistance, which was prepared by a facile and green method, may have potential applications in building development and the replacement of OPC.