engleski

A mathematical model for prediction of compressive strength in cement-silica fume blends

In the present study, a mathematical model has been developed to predict cement properties from the discription of hydration kinetics in Portland-slag cement - silica fume blends containing up to 15 mass % of silica fume. Knudsen's dispersion models were applied in fitting both the degree of hydration and the compressive strength experimental data as a function of time. It was found that the "mixed (linear/parabolic) dispersion model" fits the cement-silica fume blend systems well, as both the rate constants k1 and k2 of the Knudsen expressions are significant in the systems to which they are referring. With respects to the fact that there is a relationship between parameters as defined by Knudsen, this study has attempted to establish the direct funcional dependence between the degree of hydration and the compressive strength by means of the time variable. It was found that the degree of hydration - the compressive strength dependence, for replacement levels varying from 0 to 15 mass % of silica fume, indicates a linear mathematical function. There are good agreements between the model and experimentally obtained results. The proposed model provides the opportunity to predict the compressive strengths development based on measuring the heat release during the 48-h cement hydration if the infinitely (ultimate) achievable compressive strength value is known.

silica fume-cement blends; cement hydration; heat hydration; strength development; modelling

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