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

点击翻译按钮获取中文摘要

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.