Quantitative Study on Growth and Porosity of C-S-H Structures: Experiments and Simulations

Abstract

Coupling of microstructural and physico-chemical modelling of cement hydration is a key step towards prediction of material performance. In this paper, a physico-chemical model based on surface reactions and ion transports is proposed to capture the development of calcium-silicate-hydrate (C-S-H) not only at an early age but also at later ages of hydration (e.g, up to 28 days). Furthermore, we introduce a random sampling method to quantify pore size distribution and phase fractions in the 3D simulation, which are available for the comparison with experimental data. The latest experimental techniques were used to quantify the development of the C-S-H as well as its pore sizes, e.g. SEM, NMR, XRD during hydration. By combining observations from experiments and simulations, we can explain why the density of C-S-H does not change significantly at later ages according to NMR analysis, whilst it is widely accepted that densification occurs during hydration.

Keywords: microstructure, C-S-H phases, sheet growth model, pore-size distribution