Effects of Compounding Mineral Admixtures on High-Temperature Resistance of Magnesium Potassium Phosphate Cement

doi:10.16552/j.cnki.issn1001-1625.2025.0316

Abstract

Abstract: In order to investigate the synergistic improvement of the high-temperature resistance of magnesium potassium phosphate cement (MKPC) by compounding fly ash and silica fume. In this paper, the compressive strength tests of MKPC at four temperatures (25, 400, 600 and 800 ℃) were conducted by varying the relative content of compounding fly ash and silica fume. The appearance, mass loss and compressive strength of MKPC treated at different temperatures were investigated. Additionally, the phase composition and microstructure of MKPC were analyzed using X-ray diffractometry (XRD) and scanning electron microscopy (SEM). The results indicate that after exposure to high-temperatures, the mechanical properties of MKPC without fly ash and silica fume decrease sharply, while specimens with 15% or 10% (mass fraction) silica fume show significant improvement. When the mass fractions of fly ash and silica fume are 5% and 15%, respectively, the mechanical properties of MKPC after high temperature are better. The high-temperature dehydration of K-struvite (MgKPO₄·6H₂O), the hydration product of MKPC, is the main reason for the mass loss and compressive strength reduction of MKPC. Silica fume and fly ash can promote the sintering of the phase and amorphous particles after the decomposition of K-struvite to form a ceramic-like structure, thereby improving the high-temperature resistance of MKPC. Interestingly, the improvement of silica fume on the high-temperature resistance of MKPC is greater than that of fly ash.

Key words: magnesium potassium phosphate cement, fly ash, silica fume, high-temperature resistance, microstructure, phase analysis

CLC Number:

TQ172

LI Shuichang, HUANG Chen, MO Shimin, ZHAO Xicheng. Effects of Compounding Mineral Admixtures on High-Temperature Resistance of Magnesium Potassium Phosphate Cement[J]. BULLETIN OF THE CHINESE CERAMIC SOCIETY, 2025, 44(10): 3773-3780.

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