Transforming wood waste into water-resistant magnesia-phosphate cement particleboard modified by alumina and red mud

This study proposed a novel use of alumina and red mud to improve water resistance of MPC particleboards. Cement hydration chemistry and microstructure characteristics were revealed by quantitative X-ray diffraction analyses and scanning electron microscopy. Addition of alumina or red mud (Mg/Al or Mg/Fe at optimal molar ratio of 10:1) facilitated formation of amorphous Mg–Al or Mg–Al–Fe phosphate gel, respectively, which enhanced compressive strength. Alumina improved short-term water resistance, whereas red mud provided better long-term water resistance. Red mud-MPC binder enhanced strength retention (by 22.8%) and reduced water absorption (by 26.4%) of particleboards after 72-h water immersion, probably attributed to stable scaly-like Mg–Al–Fe phosphate gel. This study demonstrated that red mud and wood waste are sustainable materials for producing particleboards.