Predicting pore volume, compressive strength, pore connectivity, and formation factor in cementitious pastes containing fly ash

Abstract

This paper describes the use of thermodynamic modeling to predict the reaction products and properties of cementitious pastes containing fly ash. A pore partitioning model is used to estimate the gel and capillary pore volumes. The paste performance is predicted in terms of its porosity, compressive strength, formation factor, and deicing salt damage susceptibility. A model is proposed to quantify the pore refinement that occurs when fly ash is used. Comparisons are made between the predicted properties by the model and properties of experimentally measured cementitious pastes with two fly ashes at different water-to-binding ratios and varying replacement levels. The error in predicting porosity is 5%; compressive strength is 14% for OPC systems and 26% for OPC + FA systems; and formation factor is between 1 and 20% for OPC systems, 13–26% for the OPC+20%FA systems, and 18–46% for the OPC+40%FA systems.