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Approximate content of cement compounds

Gypsum % Type of cement
CaSO4 C4AF C3A C2S C3S
Ordinary
2.5 8 20 05 94 Repid hardend
3.9 8 12 15 56
2.9 13 5 46 30 Low heat
2.7 12 4 36 43 Sulfate resistance

Difference between setting and hardening of cement
 Setting of cement refers to changes of cement paste from a fluid to rigid

state
 hardening of cement refers to the gain of strength of a set cement paste

Initial and final set of cement
 Initial set: Time from moment water is added untill the paste ceases to

be fluid and plastic.
 Final set: Time from moment water is added for the paste to acquire a

certain degree of hardeness.

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