Describe the main characteristics of the five stages of hydr

Describe the main characteristics of the five stages of hydration process of portland cement.

Solution

Chemistry of Hydration - It is assumed that each compound hydrates independently of others in Portland cement. This is not completely true because interaction between hydrating compounds will affect the mix.

Calcium Silicates - The hydration reaction of the two calcium silicates, which make up the largest percent of Portland cement, are similar.

Tricalcium Aluminate - Hydration of C3A occurs with sulfate ions supplied by dissolved gypsum. The result of the reaction is calcium sulfoaluminate hydrate, called \"ettringite\" after a naturally occurring mineral.

Ferrite Phase (C4AF) forms the same hydration products as C3A, with or without gypsum. The reaction is slow and is decreased further by gypsum. If the iron oxide content is increased, the reaction is slower.