Multimodal study of unaltered cement hydrating pastes: combined high-energy laboratory powder diffraction and microtomography.

Abstract

Background: The study of the hydration pathways of Portland cement (PC) and cement blends presents significant challenges due to their multiphase nature and varying fineness. Quantifying the dissolution of initial crystalline and amorphous phases, along with the formation of new components, is crucial. Additionally, understanding microstructural changes with time is also essential. Techniques: We are developing a novel approach based on in situ measurements of cement pastes without sample conditioning. The pastes are injected in thick capillaries (2 mm of diameter) and just the ends are sealed. Sequential data acquisition is carried out through Mo-Kα1 laboratory X-ray powder diffraction (LXRPD) and microtomography (μCT) [1-2]. This methodology is based on scanning not only the same capillary but the same volume over time to minimize variability. The use of wide capillaries is pivotal for artefact avoidance, including self-desiccation, and ensuring excellent particle averaging.