Modelling Hysteresis in the Water Sorption and Drying Shrinkage of Cement Paste

E. Masoero, M. B. Pinson, Patrick Alain Bonnaud, H. Manzano, Q. Ji, S. Yip, J. J. Thomas, M. Z. Bazant, K. Van Vliet, H. M. Jennings

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Citation (Scopus)

Abstract

Shrinkage can be critical for the strength and durability of drying cement pastes. Shrinkage becomes particularly severe at very low relative humidity, < 20%, which can be met in some activities involving extreme temperatures. Experiments and simulations suggest that small pores in the cement paste, with approximate thickness ≤ 1 nm, stay saturated unless the humidity drops below 20%. Here we suggest that this pore size can define two different categories of pores in the paste: pores thicker than 1 nm, where the Kelvin's equation and the corresponding capillary (Laplace) pressure apply, and pores thinner than 1 nm, which can be considered as part of the solid skeleton if the humidity stays above 20%. 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 ∼ 20%. At lower humidities, we assume that (1) during adsorpion water re-enters the smallest pores throughout the entire RH range (supported by experiments and simulations) and (2) there exists a simple linear relationship between water and strain in the smallest pores. These minimal assumptions are sufficient to explain the low-humidity hysteresis of water content and strain, but the underlying mechanistic explanation is still an open question. Combining the low-humidity and high-humidity models allows capturing the entire drying and rewetting hysteresis, and provides parameters to predict the corresponding dimensional changes.

Original languageEnglish
Title of host publicationCONCREEP 2015
Subtitle of host publicationMechanics and Physics of Creep, Shrinkage, and Durability of Concrete and Concrete Structures - Proceedings of the 10th International Conference on Mechanics and Physics of Creep, Shrinkage, and Durability of Concrete and Concrete Structures
EditorsJohann Kollegger, Christian Hellmich, Bernhard Pichler
PublisherAmerican Society of Civil Engineers (ASCE)
Pages306-312
Number of pages7
ISBN (Electronic)9780784479346
DOIs
Publication statusPublished - 2015 Jan 1
Event10th International Conference on Mechanics and Physics of Creep, Shrinkage, and Durability of Concrete and Concrete Structures, CONCREEP 2015 - Vienna, Austria
Duration: 2015 Sep 212015 Sep 23

Publication series

NameCONCREEP 2015: Mechanics and Physics of Creep, Shrinkage, and Durability of Concrete and Concrete Structures - Proceedings of the 10th International Conference on Mechanics and Physics of Creep, Shrinkage, and Durability of Concrete and Concrete Structures

Other

Other10th International Conference on Mechanics and Physics of Creep, Shrinkage, and Durability of Concrete and Concrete Structures, CONCREEP 2015
CountryAustria
CityVienna
Period15/9/2115/9/23

ASJC Scopus subject areas

  • Mechanics of Materials
  • Building and Construction

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    Masoero, E., Pinson, M. B., Bonnaud, P. A., Manzano, H., Ji, Q., Yip, S., Thomas, J. J., Bazant, M. Z., Van Vliet, K., & Jennings, H. M. (2015). Modelling Hysteresis in the Water Sorption and Drying Shrinkage of Cement Paste. In J. Kollegger, C. Hellmich, & B. Pichler (Eds.), CONCREEP 2015: Mechanics and Physics of Creep, Shrinkage, and Durability of Concrete and Concrete Structures - Proceedings of the 10th International Conference on Mechanics and Physics of Creep, Shrinkage, and Durability of Concrete and Concrete Structures (pp. 306-312). (CONCREEP 2015: Mechanics and Physics of Creep, Shrinkage, and Durability of Concrete and Concrete Structures - Proceedings of the 10th International Conference on Mechanics and Physics of Creep, Shrinkage, and Durability of Concrete and Concrete Structures). American Society of Civil Engineers (ASCE). https://doi.org/10.1061/9780784479346.035