Cement
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Types
Cement normally consists of a 30:20:1 ratio of calcium oxide, silicon dioxide, and gypsum. Some aluminum oxide can be substituted for silicon dioxide.
Portland Cement
C3S / Alite | 50% | {{#Chem: 3CaO*SiO2}} | C3S + 6H = C-S-H + 3CH Alite + 6 Water = C-S-H + 3 Portlandite |
+120cal/g | very reactive compound, high heat of hydration, high early strength |
---|---|---|---|---|---|
C2S / Belite | 25% | {{#Chem: 2CaO*SiO2}} | C2S + 4W = C-S-H + CH Belite + 4 Water = C-S-H + Portlandite |
+62cal/g | low heat of hydration, slow reaction |
C3A / Celite | 10% | {{#Chem:3CaO*Al2O3}} | C3A + CSH2 = Ettringite Celite + Gypsum = Ettringite |
+300cal/g | problems with sulfate attack, high heat of hydration |
C4AF | 10% | {{#Chem:4CaO*Al2O3*Fe2O3}} | Absorbs excess sulfate to prevent it from poisoning other reactions | ||
Gypsum | 5% | {{#Chem:CaSO4}} | used to control the set of cement |
These materials form at 1450°C. The C-S-H component is what drives the wet-set to completion and results in the strong cement bond in the finished product.