Microstructure and early-age properties of Portland cement paste - Effects of connectivity of solid phases

Abstract

The development of the mechanical properties (compressive strength and dynamic moduli) of a hardening cementitious material is the result of the microstructural evolution due to cement hydration. In this paper, the effect of the connectivity of the solid phase in the microstructure on the mechanical behavior of cement pastes is investigated in detail. The development of the compressive strength and elastic moduli of the portland cement pastes with three different water-cement ratios (0.35, 0.5, and 0.6) cured under an isothermal condition (25°C) were studied experimentally. Parallel with the experiments, the cement hydration model HYMOSTRUC3D was used to simulate the formation of the microstructure. The connectivity of the solid phases was represented by two parameters: percolation and the specific effective contact area. Correlations have been established between the development of the connectivity of the solid phase simulated with the model and the development of the compressive strength and the dynamic moduli. It is believed that the connectivity of the solid phase in the microstructure is an essential factor that dominates the development of the mechanical properties of cement-based materials at early ages. Copyright © 2005, American Concrete Institute. All rights reserved.