磷酸盐对粉煤灰-水泥体系影响的研究

Effect of phosphate on fly ash cement system

本文研究了不同掺量磷酸盐对粉煤灰-水泥体系的强度、工作性能等宏观性能以及水化程度等微观性能的影响,结果表明:1随着磷酸钠掺量的增大,粉煤灰-水泥体系胶砂流动度随之增大,且胶砂流动度经时损失有所改善,各体系的初凝时间和终凝时间延长,标准稠度用水量略有降低;2粉煤灰-水泥体系掺入磷酸钠后,7d强度提高达15%,28d强度最多提高14%,粉煤灰激活效果显著;且化学结合水含量的变化规律与胶砂抗压强度发展变化是一致的;3掺加磷酸钠的胶砂试样安定性良好;将磷酸钠与硫酸钠等量复掺于粉煤灰-水泥体系后相互补偿缺陷,有效地激活了粉煤灰早期和后期强度,证明磷酸钠与硫酸钠相容性较好;4磷酸钠的掺入使粉煤灰反应程度在7d即高于基准组,28d龄期下相较硫酸钠仍体现了良好的促进水化进程的效果,佐证了磷酸盐对粉煤灰的激活作用。

The effects of different dosage of additional phosphate content on the strength, workability and hydration degree of fly ash-cement system were studied. The results indicated that the mortar fluidity of the fly ash-cement system would be increased with phosphate content increasing, and the fluidity loss with time of fly ash-cement system would be improved. The initial setting time and final setting time would be elongated with phosphate content increasing, and the water requirement of normal consistency would be slightly decreased. The 7d strength of fly ash-cement system increased 15% and the 28 d strength increased 14% with the addition of sodium phosphate, the fly ash has a notable activation effect. The variation of the compressive strength of mortar was similar to the variation of the chemically combined water content.The mortar of fly ashcement system with sodium phosphate would have a good long-term stability. The compressive strength of both early and later age of fly ash would be increased if the addition content of sodium phosphate were equal to the addition content of sodium sulfate, and there was good compatibility between sodium phosphate and sodium sulfate. The 7d reaction degree of fly ash was higher than baseline group after adding sodium phosphate, and the sodium phosphate has better effect on accelerating hydration than sodium sulfate at 28 d, and it proved the sodium phosphate has activation effect on fly ash.