2. Desired concrete characteristics

2.1 Plug

The combination of cement and water generates complex reactions. The silicates and aluminates that develop during the hydration phase form a crystalline gel that marks the start of the setting process.

The development and multiplication of these micro-crystals during the hardening phase, which can last several months, explains the increase in mechanical strength and makes cement a true "composite rock".

Before reaching its final stage and during hydration, cement paste goes through three successive phases:

• the dormant phase: the dough remains apparently unchanged despite the start of the first reactions;

• the start of setting: after 1 to 2 hours for most cements,...