Colloid model of C-S-H and implications to the problem of creep and shrinkage

A model for the structure of calcium silicate hydrate (C-S-H) at the nanometer level (hereafter referred to as "nanometer structure") is described, along with its possible contribution to the understanding of the mechanisins of drying shrinkage and creep in cement paste. The model was developed in two stages and describes C-S-H gel as an aggregation of precipitated, colloidal-sized particles. It was developed in an attempt to account for a number of physical characteristics of C-S-H in mature pastes, including density, surface area, fractal character, pore structure and size of individual particles. In this article the model is extended to include an hypothesis for the mechanisms of viscous deformation under load and/or during drying. As with the original model, the extension proposed here is intended to explain as much apparently unrelated data as possible. Aging (the part unrelated to the increasing amount of hydration products with time) is a process of increasing the number of bonds between globules of C-S-H, causing the C-S-H to become stiffer, stronger, and denser. M;e propose that deformation is the result of the globules moving under stress or drying, but the mechanism or type of rearrangement of the C-S-H particles [globules] depends on age and on whether or not the sample is dried or loaded or both.