Hydration kinetics of tricalcium silicate by calorimetric methods

The kinetics of the cement hydration reaction is a relevant issue in the cement research field, particularly in the presence of additional inorganic and organic components that consistently increase the complexity of the cement paste. In the present study, the hydration reaction of pure tricalcium silicate has been monitored by different calorimetric approaches: the conventional Isothermal Conduction Calorimetry (IC) and a novel Differential Scanning Calorimetry (DSC) protocol. The measured hydration curves have been modeled by using the Boundary Nucleation and Growth Model (BNGM) to extract thermodynamic parameters of the early stages of the hydration reaction. IC and DSC methods provide similar results in terms of rate constants, linear growth, and nucleation rates even though the IC accesses the total evolved heat while DSC discloses the fraction of unreacted water. The validation of the DSC approach as a reliable analytical method to the study of cement hydration kinetic is of particular importance because it allows following very long hydration processes, such as those of pastes containing organic retarders or superplasticizers. The thermodynamic and kinetic parameters for the tricalcium silicate setting has been also evaluated and discussed as a function of the surface area of the powder.

Graphical abstractDSC is a reliable analytical technique to study the cement hydration by monitoring the unreacted water. This opens new possibilities for the investigation of more complex cement samples containing superplasticizers.Figure optionsDownload full-size imageDownload high-quality image (157 K)Download as PowerPoint slideHighlights► The hydration reaction of a tricalcium silicate paste is studied using DSC. ► DSC method and the classical IC method are well in accordance. ► Boundary Nucleation and GrowthModel is applied to compare DSC and IC techniques.