硅酸盐水泥水化动力学简化模型

A simplified model of hydration kinetics for portland cement

摘要:

为了更加清晰地阐明水灰比对硅酸盐水泥水化进程的影响,分析了硅酸盐水泥的水化动力学模型(Tomosawa模型,T模型),并将其简化为由传质过程、相界面反应和扩散过程所组成的简化T模型．结合化学结合水法测定水化程度,应用T模型及简化T模型对两种不同水灰比水泥浆体的水化动力学进行研究．结果表明:水泥水化动力学模型中的参数受水灰比的影响各异,其中与传质过程相关的参数几乎不受水灰比的影响;与相界面反应相关的参数受水灰比的影响较小;而与扩散系数相关的参数受水灰比影响显著．简化T模型可以较好地分段模拟水化速率随水化程度变化的总体趋势,且该趋势不受水灰比影响,但是相界面反应控制向扩散过程控制转变时的临界水化程度受到水灰比的影响,且随水灰比增加,临界水化程度增大．

Abstract:

To more clearly elaborate the influence of water-cement ratio (w／c) on hydrate process of Portland cement, the kinetic model (Tomosawa model, T model) of hydration was analyzed and simplified. In simplified T model, the hydration process was controlled by mass transfer, interfacial reaction and diffusion process at different stages, respectively. Based upon the degree of hydration measured by chemical bound water method, T model and simplified T model were applied to investigate the relationship between the degree of reaction and hydration rate for cement pastes with different water-cement ratios. The results show that the effects of w／c on the parameters in the T model are different. Along with the change in w／c, the coefficients of mass transfer are almost unaffected, the interfacial reaction coefficient is less affected, while the diffusion coefficient is significantly affected. The development trend of hydration rate with degree of reaction at different stages can be well simulated by simplified T model, which is not affected by w／c. However, the critical degree of hydration from interfacial reaction to diffusion process is increased with the increasing of w／c.