Effects of the modified expanded perlite materials on magnesium phosphate cement-based fireproof mortars: Mechanical property, thermal conductivity and microstructure

This paper focuses on the expanded perlite modifications and their effects on the properties of magnesium phosphate cement-based fireproof mortars. Silane impregnation solution, water glass, and stearic acid were employed for surface hydrophobicity modification of the expanded perlite particles. Eight types of the magnesium phosphate cement–based fireproof mortars were fabricated with and without various modified expanded perlite particles. The magnesium phosphate cement–based fireproof mortar morphology was characterized by a scanning electron microscope–energy–dispersive X–ray spectroscopy. The weight loss and chemical compositions of each magnesium phosphate cement–based fireproof mortar were visually analyzed by thermogravimetry and X–ray diffraction, respectively. Analysis reveals that the silane impregnation solution has a greater effect than stearic acid and water glass on the surface modification of the expanded perlite particles. The magnesium phosphate cement–based fireproof mortar prepared with the expanded perlite particles modified by the silane impregnation solution has better properties in terms of compressive strength and fire resistance than that by others, regardless of hydration age. In addition, the findings, in terms of mortar micrographs, thermogravimetry and chemical components, can contribute to explaining the differences observed in the performance of various magnesium phosphate cement–based fireproof mortars.