Intrinsic elastic properties of Calcium Silicate Hydrates by Nanoindentation

摘要

Calcium Silicate Hydrate (C-S-H) nanoparticles were partially recrystallized by Ostwald ripening after long-term equilibrium in calcium hydroxide solution of different concentration, leading to C-S-H of different Ca/Si ratio. The atomically smooth microdomains obtained have made possible the investigation of the intrinsic elastic properties of C-S-H in the direction perpendicular to the plane of the silicate layers. This has been carried out by nanoindentation using an experimental device based on the Atomic Force Microscope. Results have shown that the intrinsic elastic modulus of C-S-H drastically increases with the Ca/Si ratio, which may be explained by the change in structural and chemical properties of the C-S- H interlayer. Results for C-S-H of low Ca/Si ratio are in perfect agreement with theoretical results of the literature. It is, to our knowledge, the first time that experimental values of the intrinsic elastic modulus of C-S-H particles are reported. It could bring some important insight to the understanding of mechanical properties of cement-based materials.