Composition of cement

C3S and C2S

1. Most stable
2. 70-80 % of the constitution in cement
3. C3S hydrates rapidly and develop strength early during the first 14 days . In contrast , C2S hydrates slowly and develop strength after 7 day . Rich in C2S = greater resstance to chemical attack and has a smaller drying shringkage than other portland cements

C3A

1. Least stable
2. Hydration is extremly exothermic and takes very quickly , produce little strength after 24 hour
3. Susceptible to sulphate attack

C4AF

1. Less important
2. Is coloured due to red brown ferric oxide