Title: Modeling the Heat Development of Concrete Associated with Cement Hydration

Author(s): C.V. Nielsen

Publication: Symposium Paper

Volume: 241

Issue:

Appears on pages(s): 95-110

Keywords: activation energy; Arrhenius; equivalent age; heat generation; hydration; maturity; semi-adiabatic.

DOI: 10.14359/18653

Date: 4/1/2007

Abstract:
The maturity concept applying the Arrhenius equation is generally accepted as a proper way to model the temperature effects on concrete hardening. The Arrhenius equation gives the rate of hydration as a function of temperature depending on the activation energy for the cementitious binder materials. It is demonstrated how a simple three-parameter-model is sufficient to formulate the development of heat from the cement hydration process. Furthermore, the heat development is used to define the apparent degree of hydration. It is described how the heat of hydration may be determined experimentally at the con-crete plant or in nearby concrete laboratories. By means of a semi-adiabatic container the heat released from the hydration process is monitored. Finally, examples of the practical applications of the heat of hydration data for various concrete mixtures are addressed. It is demonstrated how the use of admixtures may influ-ence the heat of hydration and how difficult it is to model the complicated interactions between cement, mineral additions and admixtures without the use of experiments. The possibility of linking the heat of hydration data with the early-age mechanical properties is also illustrated.