Hydration of clinker

Hydration of Clinker Phases (J/g) for some types of cements, measured according to PN-EN... 

Uchikawa, H. and others, "Influence of CaSO 2Hp, CaSO l/2Hp, and CaSO on the Initial Hydration of Clinker Having Different Burning Degree," Journal of Research, Onoda Cement Co., Vol. 36, No. 112,1984, pp. 55-67. 

Popular models of hydration of clinker minerals can be divided into the delayed nucleation model and the protective layer model. 

As the rate of hydration of clinker grains appears to be determined by the rate of diffusion of water molecules through the colloidal C-S-H gel layer, the rate of reaction is a function of the permeability and cohesion of the layer. 

During the setting of a cement, a large amount of added water will be used to form hydrate phases such as C-S-H, portlandite, and AFt and AFm phases. Yet, even after complete hydration some free water will remain confined within the porous C-S-H gel and the capillary pore spaces. Notably, this occurs when surplus water is added so that the water/cement (W/C) ratio exceeds 0.6. A lack of water (W/C raho <0.2) results in an incomplete hydration of clinker minerals. The optimum W/C raho for Portland cement, leading to maximum strength, is 0.3 < W/C < 0.5. 

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