Hysteresis from multiscale porosity: Modeling water sorption and shrinkage in cement paste

Matthew B. Pinson, Enrico Masoero, Patrick A. Bonnaud, Hegoi Manzano, Qing Ji, Sidney Yip, Jeffrey J. Thomas, Martin Z. Bazant, Krystyn J. Van Vliet, Hamlin M. Jennings

Research output: Contribution to journalArticlepeer-review

56 Citations (Scopus)

Abstract

Cement paste has a complex distribution of pores and molecular-scale spaces. This distribution controls the hysteresis of water sorption isotherms and associated bulk dimensional changes (shrinkage). We focus on two locations of evaporable water within the fine structure of pastes, each having unique properties, and we present applied physics models that capture the hysteresis by dividing drying and rewetting into two related regimes based on relative humidity (RH). We show that a continuum model, incorporating a pore-blocking mechanism for desorption and equilibrium thermodynamics for adsorption, explains well the sorption hysteresis for a paste that remains above approximately 20% RH. In addition, we show with molecular models and experiments that water in spaces of ≲1 nm width evaporates below approximately 20% RH but reenters throughout the entire RH range. This water is responsible for a drying shrinkage hysteresis similar to that of clays but opposite in direction to typical mesoporous glass. Combining the models of these two regimes allows the entire drying and rewetting hysteresis to be reproduced accurately and provides parameters to predict the corresponding dimensional changes. The resulting model can improve the engineering predictions of long-term drying shrinkage accounting also for the history dependence of strain induced by hysteresis. Alternative strategies for quantitative analyses of the microstructure of cement paste based on this mesoscale physical model of water content within porous spaces are discussed.

Original languageEnglish
Article number064009
JournalPhysical Review Applied
Volume3
Issue number6
DOIs
Publication statusPublished - 2015 Jun 17

ASJC Scopus subject areas

  • Physics and Astronomy(all)

Fingerprint Dive into the research topics of 'Hysteresis from multiscale porosity: Modeling water sorption and shrinkage in cement paste'. Together they form a unique fingerprint.

Cite this