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Heat of hydration of Portland high-calcium fly ash cement incorporating limestone powder : effect of limestone particle size

机译:掺石灰石粉的波特兰高钙粉煤灰水泥的水化热:石灰石粒径的影响

摘要

This study investigated the limestone powder (IS) particle size effect on the heat of hydration of Portland cement (PC) and high-calcium fly ash (FA) systems. The LS used has a maximum particle size of 5 and 20 mu m, respectively. Isothermal calorimetry was used to measure the heat evolution during the hydration process of the cement and PC-FA pastes. The results show the particle size of LS had a significant influence on the observed heat of hydration both on rate of reaction and total amount of heat release. The hydration rates of both PC-LS and PC-FA-LS systems were accelerated by 5 mu m IS, while 20 mu m LS did not. For PC-FA-LS system, the total heat release at 48 h when using 5 mu m LS were higher than FA at 30% replacement level whereas 20 mu m LS showed similar total heat release. However, the total heat release of these ternary mixtures with both LS particle sizes was still lower than PC control. X-ray diffraction (XRD) technique and thermogravimetric (TG) analysis were applied to identify the hydration products. XRD results show the formation of carboaluminates and ettringite was still found at 28 days, indicated the stabilization of ettringite when both LS particle size were used. The reaction between LS and PC or FA was confirmed by TG results in the reduction of CaCO3 content.
机译:这项研究调查了石灰石粉(IS)粒度对硅酸盐水泥(PC)和高钙粉煤灰(FA)系统水化热的影响。所用的LS的最大粒径分别为5和20μm。等温量热法用于测量水泥和PC-FA糊料水合过程中的热量散发。结果表明,LS的粒径对观察到的水合热对反应速率和放热量总量都有重要影响。 5 µm IS可以加速PC-LS和PC-FA-LS系统的水合速率,而20 µm LS则不会。对于PC-FA-LS系统,当使用5μmLS时,在48 h时的总热量释放高于FA在30%替换水平下的总热量释放,而20μmLS则显示相似的总热量释放。但是,这两种LS粒径的三元混合物的总热量释放仍低于PC对照。 X射线衍射(XRD)技术和热重分析(TG)用于鉴定水合产物。 XRD结果表明,在28天时仍发现碳铝酸盐和钙矾石的形成,表明当使用两种LS粒径时钙矾石均稳定。 TG证实LS与PC或FA之间的反应导致CaCO3含量降低。

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