低温条件下磷酸镁水泥的失效研究

Failure Mechanism of Magnesia-phosphate Cement under Low Temperature Curing Condition

运用X射线衍射、压汞、扫电子显微镜等测试分析手段研究了低温养护条件下MPC失效试件的表面析出物性质和水化产物,从机理上探讨低温对MPC材料的破坏作用。结果表明:结果表明低温养护下失效材料表面析出结晶的主要成分为MgKPO4·6H2O(MKP),低温下,材料毛细孔的自由水结冰膨胀和膨胀性针状MKP结晶在浆体内部孔隙和微裂纹处生长,是材料的主要破坏失效机制。同时粉煤灰的加入对于改善材料孔结构、促进浆体水化程度有一定的作用。

The failure samples under low temperature curing condition were studied by X-ray diffraction, scanning electron microscopy and mercury intrusion porosimetry. The character of the hydration products the crystal on surface and the destruction effects of low temperature were investigated when MPC pastes were cured in under low temperature. The results show that the main crystal on the surface under low temperature are MgKPO4 · 6H2O （MKP）, and the phenomenon of freeze expansion of Free water and the massive expansile MKP crystallines with needle-like morphology in the inner pores is the principal failure mechanism for MPC. Meanwhile, the fly ash can improve the pore-structure and hydration degree of MPC.