摘要
Portland cement(PC) containing high-volume fly ash(HVFA) is usually used to obtain economical and more sustainable merits, but these merits suffer from dramatically low compressive strength especially at early ages. In this work, the possibility of using micro-size metakaolin(MSK) particles to improve the compressive strength of HVFA paste before and after subjecting to high temperatures was studied. To produce HVFA paste, cement was partially substituted with 70% fly ash(FA), by weight. After that, FA was partially substituted with MSK at ratios fluctuating from 5% to 20% with an interval of 5%, by weight. The effect of MSK on the workability of HVFA mixture was measured. After curing, specimens were subjected to different high temperatures fluctuating from 400 to 1000 ℃ with an interval of 200 ℃ for 2 h. The results were analyzed by different techniques named X-ray diffraction(XRD), thermogravimetry(TGA) and scanning electron microscopy(SEM). The results showed that the incorporation of MSK particles into HVFA mixture exhibited a negative effect on the workability and a positive effect on the compressive strength before and after firing.
包含高掺量粉煤灰(HVFA)的硅酸盐水泥(PC)具有经济和可持续的诸多优点,但这些优点在早期易受低抗压强度影响。本文研究了微粒径偏高岭土(MSK)粒子提高HVFA膏体受高温抗压强度的可能性。为了生产HVFA膏体,水泥用质量分数为70%的粉煤灰(FA)代替。之后,FA用质量分数为5%到20%的MSK代替,FA质量分数变化为5%。测定了MSK对HVFA混合物加工性能的影响。固化后,试样被持续置于400~1000℃的不同高温下2 h,间隔温度为200℃。采用X射线衍射(XRD)、热重(TGA)、扫描电镜(SEM)等对结果进行分析。结果表明,在高温高压混合料中掺入MSK颗粒对加工性能有负面影响,对高温抗压强度有正面影响。
