engleski

Determination of kinetic parameters in cement hydration

The differential microcalorimetric technique was applied in order to study cement hydration. A differential microcalorimeter was used to measure heat evolved during hydration of cement samples ; this was a starting parameter in analysis of kinetics of this complex heterogeneous chemical reaction. Based on the results obtained for heat released and degree of progress of hydration against the duration of hydration, this paper introduces a systematic approach for calculation of the important kinetic parameters in this process. The induction period, Gibbs free energy of activation, and the equilibrium constant of nuclei formation of new phase during the induction period of cement, hydration, were determined by introducing an admixture based on the naphthalenesulphonic acid condensate with formaldehyde into the cement-water system. The Avrami's rate constant and the Arrhenius apparent activation energy were determined as kinetic parameters for the period of accelerated hydration. Mathematical analysis of the hydration kinetics models applied makes it possible to get an insight into the mechanism governing the basic reaction which is characteristic of the hydration process under the given operating conditions.

diferential microcalorimeter ; hydration cement ; kinetic parameter

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