Thermodynamic simulation of Portland cement hydration with different water content

Portland cement hydration in normal conditions is a complex problem. A detailed description of cement hydration processes includes the clinker dissolution, diffusion process, surface phenomena of new phase nuclei, quantification of solid phases, growth in hydration products, porous structure, and moisture, depending on curing time and water/cement ratio. Thermodynamic simulation of Portland cement hydration based on the Lothenbach model, substantially assists in solving these problems. Gibbs energy minimization thermodynamic software is used to evaluate in equilibrium conditions the quantitative content of both initial clinker minerals and hydration products (hydrated cement, portlandite) for a long time. This paper presents code GEMS simulation results of the phase content during Portland cement hydration, in terms of the Lothenbach model, in the absence of such mineral additives as calcite, lime, anhydride, gypsum, hemihydrate, potassium sulphate. The water/cement ratio is proposed to be 0.3, 0.4, and 0.5. It is found that the final products mostly contain calcium silicate hydrate gel of a complex composition, portlandite, nonsoluble clinker minerals, hydrogarnet, monosulfate, and moisture distributed in the pore space; ettringite being absent. It is shown that the pore space grows with increasing water content. And even after 1250-day curing, the contribution of nonsoluble clinker is 20–25 g among 150 g of hydrated Portland cement.