Resolving nanoscopic structuring and interfacial THz dynamics in setting cements

Abstract

The setting dynamics of two commercial cements have been tracked over >24 hours of setting with non-destructive THz spectroscopy and neutron scattering. Two established glass ionomer cements (GICs) were measured, both exhibiting similar and commercially agreeable non-linear settings associated with changes in interfacial particle dynamics through variations in their collective low-energy vibrations. Structural evolutions in the ∼1–30 nm range were correlated with changes in small angle neutron scattering (SANS) profiles over setting. Accompanying models of the interfacial structures and the amorphous glass components of the cements helped make the dynamic and structural trends comprehensible. The combined observations helped elucidate key temporal features in the setting of the cements, whilst suggesting the functional role played by the THz vibrations, in particular at dynamically coordinated interfacial Al-atom pivots. The insights obtained could help evolve nano-scopic strategies to optimise cements and their eventual properties.