Irreversible Desiccation Shrinkage of Cement Paste Caused by Cement Grain Dissolution

Published

November 23, 2016

Author(s)

Xiaodan Li, Zachary Grasley, Jeffrey W. Bullard, Edward Garboczi

Abstract

When cementitious materials are dried, internal stresses are generated that lead to desiccation shrinkage. A portion of this shrinkage is irreversible. Based on previous research indicating that dissolution of cement grains while a cementitious composite is subjected to a state of stress can yield irreversible creep strains, it is hypothesized that the same process can lead to irreversible shrinkage during drying. This hypothesis was evaluated via computational simulations integrating the THAMES microstructural evolution model with a time-stepping finite element routine to predict the magnitude of shrinkage deformations resulting from time-dependent dissolution of cement grains during drying conditions. The simulation results indicate that the mechanism of cement grain dissolution is significant, and may help explain the source of the irreversible component of desiccation shrinkage at early ages while the hydration rate is significant. Younger specimens are predicted to exhibit larger irreversible shrinkage due to the higher hydration reaction rate, agreeing with experimental data. The magnitude of shrinkage predicted via poroelastic calculations was also compared to the output of the computational model. The results indicate that poroelasticity under-predicts the overall shrinkage of cement paste, especially the irreversible component.

Citation

Cement and Concrete Composites

Pub Type

Journals

Keywords

microstructure, shrinkage, finite element method, modeling, dissolution

Citation

Li, X. , Grasley, Z. , Bullard, J. and Garboczi, E. (2016), Irreversible Desiccation Shrinkage of Cement Paste Caused by Cement Grain Dissolution, Cement and Concrete Composites (Accessed September 7, 2024)