Investigations on cement expansion associated with ettringite formation

The formation of ettringite and the expansion associated with it were studied on pastes made from an Al-bearing compound, gypsum, and tricalcium silicate. There were significant differences in the rate at which ettringite was formed and in the capacity of the formed ettringite to generate expansion. In some systems ettringite formation was not associated with expansion. An uptake of water from the environment seems to be inessential for an expansion to take place, but intensifies its extent. (C) 1999 Elsevier Science Ltd. All rights reserved.