Abstract The hydration temperature has a considerable effect on the microstructure of cement paste. The microstructural changes with increasing curing temperature result in a significant decrease of cement mechanical properties. The present work aims at studying these phenomena via micromechanical modelling, based on an experimental characterization of cement microstructure. The pore structure of a class G oil-well cement paste (American Petroleum Institute classification) hydrated at different temperatures, between 7 °C and 90 °C is characterized. Then, the influence of the microstructure variations on the elastic properties of the hardened paste is explored through micromechanical modelling. A previous analysis of the microstructure enabled determining the volume fractions of different phases of a class G cement paste hydrated under different temperatures [1]. A multiscale self-consistent homogenization model is used based on these results to simulate the variations of the mechanical properties with hydration temperature. The results are compared with macro-scale elastic properties obtained from uniaxial compression tests. It is shown that the increasing capillary porosity with elevating hydration temperature, is not sufficient to fully explain this drop of elastic properties. The latter originates mainly from the decrease of the elastic properties of the foam composed of the porous C-S-H intermixed with capillary pores. The pore structure analysis coupled with the micromechanical modelling permitted a back-analysis of the intrinsic porosities of high density and low density C-S-H showing an almost constant LD intrinsic porosity and a significantly decreasing HD intrinsic porosity.

中文翻译：

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水化温度对水泥浆体孔隙结构的影响：实验研究和微观力学建模

摘要 水化温度对水泥浆体的微观结构有显着影响。随着养护温度的升高，显微结构的变化导致水泥力学性能的显着下降。目前的工作旨在通过微机械建模研究这些现象，基于水泥微观结构的实验表征。表征了在 7°C 至 90°C 之间不同温度下水化的 G 类油井水泥浆体（美国石油学会分类）的孔隙结构。然后，通过微观机械建模探索微观结构变化对硬化膏弹性性能的影响。先前对微观结构的分析能够确定在不同温度下水化的 G 级水泥浆的不同相的体积分数 [1]。基于这些结果使用多尺度自洽均质模型来模拟机械性能随水化温度的变化。结果与从单轴压缩试验获得的宏观弹性特性进行了比较。结果表明，随着水化温度的升高，毛细管孔隙率的增加不足以完全解释这种弹性性能的下降。后者主要源于由多孔 CSH 与毛细孔混合组成的泡沫的弹性性能下降。