Why alite stops hydrating below 80% relative humidity

Robert J. Flatt, George W. Scherer, Jeffrey W. Bullard

Research output: Contribution to journalArticlepeer-review

97 Scopus citations


It has been observed that the hydration of cement paste stops when the relative humidity drops below about 80%. A thermodynamic analysis shows that the capillary pressure exerted at that RH shifts the solubility of tricalcium silicate, so that it is in equilibrium with water. This is a reflection of the chemical shrinkage in this system: according to Le Chatelier's principle, since the volume of the products is less than that of the reactants, a negative (capillary) pressure opposes the reaction.

Original languageEnglish (US)
Pages (from-to)987-992
Number of pages6
JournalCement and Concrete Research
Issue number9
StatePublished - Sep 2011

All Science Journal Classification (ASJC) codes

  • Building and Construction
  • General Materials Science


  • A. Humidity
  • A. Hydration
  • A. Reaction


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