Kinetic and thermodynamic modeling of Portland cement hydration at low temperatures

Portland cement have to hydrate in cold climates in some particular conditions. Therefore, a better understanding of cement hydration under low temperatures would benefit the cement-based composites application. In this study, Portland cement was, therefore, kinetically and thermodynamically simulated based on a simple kinetics model and minimization of Gibbs free energy. The results of an evaluation indicate that Portland cement hydration impact factors include the water-cement ratio (w/c), temperature, and specific surface area, with the latter being an especially remarkable factor. Therefore, increasing the specific surface area to an appropriate level may be a solution to speed the delayed hydration due to low temperatures. Meanwhile, the w/c ratio is believed to be controlled under cold climates with consideration of durability. The thermodynamic calculation results suggest that low-temperature influences can be divided into three levels: irrevocable effects (< 0 A degrees C), recoverable effects (0-10 A degrees C), and insignificant effects (10-20 A degrees C). Portland cement was additionally measured via X-ray diffraction, thermal gravity analysis, and low-temperature nitrogen adsorption test in a laboratory and comparisons were drawn that validate the simulation result.