Effect of Magnesium Salt Whiskers on the Mechanical Properties of Phosphogypsum Building Blocks

Phosphogypsum (CaSO₄⋅2H₂O), as an industrial by-product widely used in the field of building materials, has garnered considerable attention for its mechanical properties. This study explores the effect of magnesium (Mg) doping on phosphogypsum's (CaSO₄⋅2H₂O) mechanical properties. Using first principles, it found that Mg doping increases the bulk, shear, and Young's moduli of phosphogypsum from 42.52445, 19.76419, and 51.33892 GPa to 48.22389, 22.98504, and 59.36072 GPa, respectively, and hardness from 3.18363 GPa to 3.6273 GPa. It also determined the interface binding stability with magnesium salts, ranking the stability as CaSO₄·2H₂O/Mg(OH)₂ > CaSO₄⋅2H₂O/MgSO₄ > CaSO₄⋅2H₂O/MgCl₂. Tests showed Mg-salt-doped phosphogypsum's compressive and flexural strength increased by 14.72% and 20.61%, respectively, enhancing its value in construction. This finding holds significant implications for enhancing the application value of phosphogypsum in the construction materials sector.