Hydration kinetics of tricalcium silicate by calorimetric methods

Area of Science:

• Materials Science
• Chemical Engineering
• Physical Chemistry

Background:

• Cement hydration kinetics are crucial for understanding cement paste behavior.
• Additional components complicate the hydration process.
• Accurate kinetic modeling is essential for cementitious materials.

Purpose of the Study:

• To compare Isothermal Conduction Calorimetry (IC) and Differential Scanning Calorimetry (DSC) for monitoring tricalcium silicate hydration.
• To validate DSC as a reliable method for cement hydration kinetics.
• To extract thermodynamic parameters using the Boundary Nucleation and Growth Model (BNGM).

Main Methods:

• Monitoring hydration of pure tricalcium silicate using IC and a novel DSC protocol.
• Modeling hydration curves with the Boundary Nucleation and Growth Model (BNGM).
• Evaluating thermodynamic and kinetic parameters based on powder surface area.

Main Results:

• Both IC and DSC yielded comparable results for rate constants, linear growth, and nucleation rates.
• DSC provides insights into the fraction of unreacted water, complementing IC's total heat measurement.
• The study validates DSC for studying long hydration processes, including those with retarders.

Conclusions:

• DSC is a validated and reliable method for studying cement hydration kinetics, particularly for extended periods.
• The Boundary Nucleation and Growth Model effectively extracts thermodynamic parameters for early hydration stages.
• Surface area significantly influences the thermodynamic and kinetic parameters of tricalcium silicate setting.