C3S (Tricalcium Silicate)
Alite — the most abundant phase in OPC and the principal contributor to early strength gain. C3S hydrates rapidly to form C-S-H gel and calcium hydroxide.
C3S typically makes up 50-70% of OPC clinker. It governs strength development in the first 28 days and contributes most of the heat of hydration in early ages.\n\nHigher C3S means faster strength but more heat — undesirable for mass concrete.
The chemical reaction between cement and water that produces hardened cementitious paste. Hydration generates heat and the binding C-S-H gel that gives concrete its strength.
Belite — the slow-reacting silicate phase in OPC. C2S contributes mainly to long-term strength beyond 28 days, with low heat generation.
The heat released as cement reacts with water. Important for thermal control in mass concrete to avoid cracking from temperature gradients.