Thermodynamic simulation of portland cement hydration with different water content

Hydration of Portland cement in normal conditions is a complex problem. A detailed description of the hydration process includes the clinker dissolution, diffusion processes, surface phenomena on the nuclei of new phases, quantitative composition of the solid matter and growth of hydration products, porous structure, humidity depending on the hardening time and water/cement ratio. Thermodynamic modeling of Portland cement hydration based on the Lothenbach model allows solving these problems to a large extent. Using GEMS software, thermodynamic simulation allows detecting the amount of both initial clinker and hydration products such as cement paste, ettringite, Portlandite, and others for a long period of time. The paper presents the simulation results of the phase content during Portland cement hydration based on the Lothenbach model, in the absence of such mineral additives as calcite, lime, anhydrite, gypsum, hemihydrate, K 2 SO 4 . The water/cement ratio is 0.3, 0.4 and 0.5. It is found that the final dominant products include CSH gel of a complex composition, portlandite, insoluble clinker minerals as well as hydrogarnet, monosulfate, humidity distributed in the porous space; ettringite is absent. It is determined that the fraction of the porous space increases with increasing water content and even after 1250 days of hardening the contribution of insoluble clinkers is 20–25 g among 150 g of hydrated Portland cement.