Effect of Superplasticizers on the Cement Hydration Process

Abstract

The cement hydration is an exothermic reaction. The hydration heat is characterizing quantitatively the clinker hydration degree. Monitoring its time response makes it possible to determine not only the heat released during a certain time interval but also the concrete mix setting onset, the cement hydration degree (when evaluating the cement applicability after a long storage period) etc. The measurement of the hydration heat or the temperature versus time plot for a hydrating mix makes it possible to identify the effect of the different additives and admixtures on the mix hydration kinetics. This paper deals with the effect of adding two different super-plasticizers (lignin-sulphonate-based and naphthalene-sulphonate-based) on the hydration heat development progress. A set of iso-peribolic calorimeters was used to measure the hydration heat development process. The measurement proper consisted in monitoring and recording the temperature versus time plot for the specimen under test. The released heat amount was determined by calculation from the temperature gradient, the ambience specific thermal losses, the material thermal capacity and the test specimen mass.

Comprehensive Review of Direct and Indirect Pozzolanic Reactivity Testing Methods

“…Due to cement's exothermic hydration reaction, the hydration kinetics of the clinker could be evaluated by measuring its heat of hydration. It is possible to characterize the effect of different additives and admixtures on the mixture's hydration kinetics through measurement of the heat of hydration versus time [59]. The most widely used equipment for studying cement hydration is isothermal and semi-adiabatic calorimeters.…”