Ponente
Descripción
Water plays a central role in the mechanical strength, durability, carbonation dynamics, and ion-driven degradation in cementitious systems. Yet the structure and dynamics of water within the poorly crystalline, nanoporous main binder phases of cement, especially in the newly emerging low-CO₂ cements, are difficult to characterize by conventional techniques. Neutron scattering offers unique advantages: its high sensitivity to hydrogen, combined with H/D isotopic contrast, makes it well suited to probing water at mineral interfaces on the molecular scale. Particularly useful is the complementary use of neutron diffraction with isotopic substitution (NDIS) and inelastic incoherent neutron scattering (IINS). The former provides element-selective resolution of interfacial water ordering, a level of structural detail inaccessible to X-ray diffraction alone. Combined with molecular dynamics simulations, NDIS can reveal distinct wet and dry surface domains and identify water-surface cation coordination as water organizes at cement surfaces. The latter characterizes water dynamics through the vibrational density of states, resolving transitions from surface-adsorbed multilayer water to capillary-condensed ice-like phases—features that calorimetric or spectroscopic methods capture only partially. Together, NDIS and IINS provide a molecularly resolved picture of interfacial water, contributing to a more detailed understanding of the role water plays in governing the performance and durability of cementitious materials.