Thermo-chemo-mechanical characterization, modeling, and analysis of hydration of calcium-sulfoaluminate cement paste

The reaction kinetic of a commercial calcium sulfoaluminate (CSA) cement was characterized by heat flow calorimetry. Distinct behavior is observed whether tartaric acid is added as retarding agent or not. Employing the so-obtained calorimetric data, heat of hydration and chemical affinity of the investigated binder mixture was determined. Furthermore, continuous ultrasonic propagation velocity measurement gave access to the stiffness gain of paste samples. However, the ultrasonic test setup is characterized by a non-constant temperature history (temperature rise and fall). Modeling the temperature history and the history of the degree of hydration with a thermo-chemical analysis scheme, the intrinsic material function of the stiffness evolution of the investigated hydrating CSA paste was obtained. Furthermore, the robustness of the thermo-chemical analysis scheme was demonstrated by the comparison of the measured with the simulated temperature evolution. The versatility of the approach may contribute to a systematic assessment and optimization of the heat/mechanical evolution of CSA binder systems under various geometric, temporal, and thermal boundary condition.