石灰石粉-粉煤灰细度变化对水泥基胶凝材料体系水化动力学的影响

为研究混磨不同细度石灰石粉-粉煤灰对水泥基胶凝材料水化进程和早期力学性能的影响规律,本文采用等温量热法测定了不同细度复合胶凝体系在水化温度为20 ℃时的水化放热速率和放热量,根据Krstulovic-Dabic提出的水化动力学模型计算了复合胶凝体系水化反应各阶段的动力学参数。结果表明:增加石灰石粉和粉煤灰的细度可促进复合胶凝体系水化产物的结晶成核与晶体生长,缩短水化诱导期结束时间和达到最大放热速率时间,加速水泥的水化反应速率。石灰石粉和粉煤灰细化会缩短相边界反应过程时间,使复合胶凝体系在水化程度更高时发生反应控制机制转变。抗压强度试验表明增加细度可明显提高胶砂试件的早期强度,其后期强度保持稳定。

Influence of Fineness Change of Limestone Powder-Fly Ash on Hydration Kinetics of Cement-Based Cementitious Material System

In order to analyze the influence of different fineness of limestone powder-fly ash on the hydration process and early mechanical properties of cement-based cementitious materials. In this study, isothermal calorimetry was used to determine the total heat release and heat release rate of composite binders with different fineness at 20 ℃. According to the hydration kinetic model proposed by Krstulovic-Dabic, the values of kinetic parameters for each stage of the hydration reaction were calculated. The results show that the increase fineness of limestone powder and fly ash will promote the crystal nucleation and crystal growth of the hydration products. At the same time, the increase of fineness will shorten the end time of hydration induction period and the time to reach the maximum exothermic rate, and accelerate the hydration reaction rate of cement. Limestone powder and fly ash refinement shorten the process time of phase boundary reaction. When the degree of hydration is higher, the reaction control mechanism in the cementitious material system changes. The compressive strength test shows that increasing the fineness can significantly improve the early strength of the mortar specimen, and the later strength remains stable.