采用等温量热法测定了矿渣掺量分别为0、30%、50%、70%、90%和粉煤灰掺量分别为0、20%、35%、50%、65%的复合胶凝材料在298K时的水化放热速率和放热量.根据Krstulovic Dabic水化动力学模型计算了反应速率常数、几何晶体生长指数等动力学参数,并讨论了水化反应各阶段的反应速率与反应程度的关系.结果表明:不同矿渣掺量和不同粉煤灰掺量的复合胶凝材料的水化过程均可表示为结晶成核与晶体生长、相边界反应和扩散3个阶段.所用动力学模型能较好地表征矿渣掺量在70%以内及粉煤灰掺量在65%以内的复合胶凝材料的真实水化过程.矿渣掺量90%的复合胶凝材料的水化机理发生了改变,所用动力学模型不再适用.
Hydration heat emission rate and quantity of cement-slag blends containing 0,30%,50%,70% and 90% of slag and that of cement-fly ash blends containing 0,20%,35%,50%,65% of fly ash were measured at 298 K using isothermal calorimetry.According to the Krstulovic-Dabic hydration kinetics model,the reaction rate constant K,the geometrical crystal growth exponent,and other kinetic parameters were calculated.The relationship between the hydration rate and the degree of hydration was discussed at different stages of hydration.The hydration process of composite binders can involve three stages,i.e.,nucleation and crystal growth,interactions at phase boundaries and diffusion.The kinetic model was used to predict the hydration process of composite binder containing no more than 70% of slag and composite binder containing no more than 65% of fly ash.This model is no longer applicable for composite binder containing 90% of slag due to the variation of its hydration mechanism.