The kinetics of cement hydration is defined as the rate at which cement particles react with water to form calcium silicate hydrates and other compounds, which leads to the hardening of concrete.

The Process of cement hydration depends on:

  • Rate of dissolution of the involved phases of cement in the initial stage and at later stages.
  • Rate of nucleation and crystal growth of hydrates
  • Rate of diffusion of water and dissolved ions through the hydrated materials already formed.

The condition to increase hydration are:

Ø  Temperature

Ø  Higher specific surface

Ø  Impurities in water


Factor affecting hydration rate of cement:

  • The phase composition of cement. Different types of cement have varying chemical compositions, which can influence the rate of hydration.
  • The amount and form of gypsum in the cement: whether gypsum is present in the dihydrate, hemihydrate. or the anhydrite form.
  • Fineness of cement: Higher the fineness, higher the rate of reaction due to availability of a large surface area.
  • water cement ratio of mix: At high W/C, hydration may progress till all the cement is consumed, while at low W/C the reaction may stop altogether due to lack of water.
  • Curing condition: The relative humidity can have major effects on the process of hydration.
  • Hydration temperature: Increase in temperature generally cause an increase in the rate of the reaction, although the hydrated structure can be different at different temperature.
  • Admixtures, such as accelerators and retarders, can be added to the mix to control the hydration rate. Accelerators speed up hydration, while retarders slow it down.
  • Presence of chemical admixture: For example, plasticizers, and set controllers.