白云石微粉对水泥早期水化性能的影响及其机制

发布时间：2018-11-17 10:45

【摘要】：为探究白云石微粉在水泥混凝土中安全和高效应用途径,以石灰石微粉为参照,采用水泥标准试验方法和等温量热法,研究白云石微粉取代量和细度对水泥凝结和放热特性的影响及其机制。结果表明:细度大于水泥的白云石和石灰石微粉均增加混合水泥用水量。与石灰石微粉对初凝时间无明显影响、小幅延长终凝时间不同,白云石微粉明显延缓初、终凝时间,且取代量和细度愈大,缓凝现象愈显著。白云石微粉与石灰石微粉均可加速早期水化和降低累计放热量,润湿期的放热速率随白云石微粉用量增加而降低,却随石灰石微粉用量增加而升高。决定混合水泥需水量变化的主要因素是碳酸盐粉体引入而致堆积密度的改变;混合水泥的缓凝主要与体系的堆积密度和微粉颗粒表面所带电位有关。润湿期放热速率差异性主要是粉体表面荷电量不同所致。
[Abstract]:In order to explore the safe and efficient application of dolomite powder in cement concrete, the standard test method of cement and isothermal calorimetry were used. The effect of dolomite powder substitution and fineness on the setting and exothermic properties of cement and its mechanism were studied. The results show that dolomite and limestone powder with fineness greater than cement increase the water consumption of mixed cement. The dolomite powder had no obvious effect on the initial setting time, but the dolomite micropowder delayed the initial setting time and the final setting time obviously, and the larger the substitution amount and fineness, the more obvious the retarding phenomenon. Both dolomite powder and limestone powder can accelerate early hydration and decrease the accumulated heat release. The heat release rate decreases with the increase of dolomite powder content, but increases with the increase of limestone powder content. The main factor to determine the water requirement of mixed cement is the change of accumulation density caused by the introduction of carbonate powder, and the retarding of mixed cement is mainly related to the packing density of the system and the potential on the surface of micro-powder particles. The difference of heat release rate during wetting period is mainly caused by the different charge on the surface of powder.
【作者单位】：南京工业大学材料科学与工程学院;
【基金】：国家自然科学基金(51472116)
【分类号】：TQ172.1

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