粉煤灰对磷酸钾镁水泥性能的影响

Effect of fly ash on properties of magnesium potassium phosphate cement paste

测试了不同粉煤灰掺量和酸碱组份比例的磷酸钾镁水泥(MKPC)浆体的抗压强度、水养护剩余强度和初始水化温度,分析了MKPC硬化体的物相组成和显微结构.结果表明:由于复合缓凝剂有效延缓了MKPC浆体的早期水化反应速度,MKPC最佳酸碱组份比例较掺硼酸盐的MKPC降低50%以上;掺适量的粉煤灰(FA)可使MKPC的水稳定性明显提高,其中酸碱组份质量比为1.0∶3.0、m(FA)/m(FA+MgO)=20%的MKPC硬化体,在水养护条件下的剩余抗压强度率超过90%.酸碱组份质量比的降低可减少MKPC硬化体中磷酸盐的溶解和水化产物的水解,FA对MKPC浆体的物理、化学作用使MKPC硬化体的结构更加致密,从而使硬化体早期水稳定性明显提高.

Magnesium potassium phosphate cement （MKPC） pastes with different contents of fly ash （FA） and ratio of acid to base were discussed through testing compressive strength,residual ratio of compressive strength after water curing and hydration temperature rise.The micro morphology and the phase composition of hardened MKPC pastes were also analyzed.The results indicate that compared to the MKPC paste with borate retarders,the optimum proportion of acid component is decreased above 50％ because of the effective delaying effect of composite retarder on the early hydration rate of MKPC paste.Some fly ash can obviously improve the water stability of hardened MKPC paste.The residual ratio of compressive strength of hardened MKPC paste with mass ratio of acid to base of 1.0 ∶ 3.0 and 20％ ash fly in water curing condition is over 90％.The dissolution of phosphate and hydrolysis in hydrates can be alleviated by the decrease of acid component content in MKPC.The micro structure of hardened MKPC paste is compacted by the physical and chemical effects of FA to improve the water stability.