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

引起硬化水泥浆体弹性、收缩和蠕变变形的微观结构机制尚不充分了解。这种知识的缺乏对控制和影响变形过程造成了重大障碍。此外，描述这些变形过程的本构方程主要基于经验，既不能满足此类模型的科学要求，也不能提供足够的精度来确保可靠的施工过程。该提案的关键目标是通过实验研究引起蠕变的微观结构机制，并将这些结果转化为基于结构物理原理的可靠材料模型。作品的中心是通过对硬化水泥浆的小尺寸样品进行收缩和蠕变研究形成的，在此基础上，使用小角x射线散射技术（SAXS）原位测量了宏观变形和微观结构变化。正如作者在先前的工作中所表明的那样，将saxs技术与机械蠕变试验相结合，可以在微观结构水平上实时无损地检测硬化水泥浆的可逆和不可逆变化。saxs技术得到的结果将得到补充，例如汞侵入孔隙度测试（MIP）和使用BET方法的吸附分析。这些经典方法进一步确保了与水泥浆体微观结构理解的最新状态的密切联系，并将允许扩展现有的微观结构模型，以考虑机械载荷的影响。

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.