Effect of Fly-Ash on Heat Evolution Due to Hydration in Portland Cement/Fly-Ash Mixtures.

The addition of fly ash in portland cement causes a decrease in the heat of hydration which evolves as an exothermic reaction. Depending on the type of cement used, temperature rises ranging up to 50 degree C and higher may occur during the setting process. These rises in temperature set up stresses in mass concrete which are liable to cause technical problems. Technologically suitable fly-ashes with good pozzolanic properties are, in Central Europe, increasingly being used as binding aegents for mass concrete construction. For this reason, the heat evolution in a number of such mixtures has been investigated and is reported in this article.