A model for two types of calcium silicate hydrate in the microstructure of Portland cement pastes

A new physical basis for a previously published model for the structure of calcium silicate hydrate (C-S-H) as measured by nitrogen sorption is described. This refined model provides a method of predicting the density, the nitrogen accessible gel porosity, and associated surface area of C-S-H in Portland cement pastes. The basis for the model is that C-S-H forms as one of two types, high- or low-density C-S-H. This provides a promising tool for characterizing the microstructure in a way that can be applied to understanding properties of engineering significance. (C) 2000 Elsevier Science Ltd. All rights reserved.