Full-scale observation of drying-induced microstructure change in hardened cement paste by water and 2-propanol 1H NMR relaxometry
Ryusei Igami, Go Igarashi, Abudushalamu Aili, Ryo Kurihara, Takahiro Ohkubo, Ippei Maruyama
Abstract
To understand the microstructural changes in the hardened cement paste during the drying, hardened white Portland cement pastes were D-dried or dried under 11, 33, 40, and 75% relative humidity, and then, pastes were impregnated with 2-propanol or water under vacuum. Measurement of 1 H NMR relaxometry was employed for the pastes before and after impregnation, and the full-scale microstructural changes of the hardened cement paste after drying were successfully visualized. It was observed that the volume of the coarse pores outside the agglomeration of calcium-silicate-hydrate (C-S-H) increased, and the volume of the C-S-H interlayer spaces and gel pores decreased as the drying relative humidity decreased. Thus, it was evidenced that interlayer space is decreasing during drying. It was also confirmed that 2-propanol can enter some of the interlayer space of C-S-H after harsh drying.