Investigation and modelling of the deformation mechanisms of hardened cement paste based on novel small angle X-ray scattering investigations

硬化水泥浆体中引起弹性、收缩和徐变变形的微观结构机制还不清楚。这种知识的缺乏对控制和影响变形过程构成了重大障碍。此外，描述这些变形过程的本构方程主要基于几何学，既不满足对这种模型的科学要求，也不提供足够的精度来确保可靠的施工过程。该提案的主要目标是通过实验研究导致蠕变变形的微观结构机制，并将这些结果转换为基于结构物理原理的可靠材料模型。该工程的中心是通过对硬化水泥浆制成的小规模样品进行收缩和徐变研究而形成的，在这些样品上使用小角X射线散射技术（SAXS）原位测量宏观变形以及微观结构变化。如作者在先前的工作中所示，SAXS技术与机械蠕变测试的组合允许在真实的时间内在微观结构水平上对硬化水泥浆的可逆和不可逆变化进行非破坏性测试。将得到的结果由SAXS技术将补充e。G.通过压汞孔隙率测试（MIP）和使用BET方法的吸附分析。这些经典的方法进一步确保了密切的连接到最先进的水泥浆体的微观结构的理解，并将允许扩展现有的微观结构模型，鉴于机械载荷的影响。

The microstructural mechanisms causing elastic, shrinkage and creep deformations in hardened cement paste are only insufficiently understood. This lack in knowledge poses a significant obstacle in controlling and influencing the deformation process. Further, constitutive equations to describe these deformation processes are primarily based on empirics and neither suffice the scientific requirements on such models nor do they provide a sufficient accuracy to ensure a reliable construction process. The key goal of the proposal at hand is to experimentally investigate the microstructural mechanisms causing creep deformations and to transfer these results into reliable material models based on structure physical principles. The center of the works is formed by shrinkage and creep investigations performed on small-scale samples made out of hardened cement paste, on which both the macroscopic deformations as well as the microstructural changes are measured in- situ using the small angle X-ray scattering technique (SAXS). As could be shown by the authors in prior work, the combination of the SAXS-technique with mechanical creep tests allows for a non- destructive testing of the reversible and irreversible changes in the hardened cement paste on a microstructural level in real time. The results to be obtained by the SAXS-technique will be complemented e. g. by mercury intrusion porosimetry tests (MIP) and sorption analysis using the BET method. These classical methods further ensure a close connection to the state of the art in the microstructural understanding of cement paste and will allow to extend existing microstructural models in view of the effect of mechanical loadings.