Question

The main role of dicalcium silicate compound in cement is:
1. for flash set
2. to retard the flash setting of cement
3. to provide ultimate later-age  strength
4. to provide colour effect in cement
5. both, for flash set and to provide ultimate later-age strength

Answer 1

Correct Answer - Option 3 : to provide ultimate later-age  strength

Concept

There are four compounds (Called Bogue's Compounds) formed as a result of hydration of cement:

Alite: C3S, or Tricalcium Silicate

Belite: C2S, or Dicalcium Silicate

Aluminate phase: C3A, or Tricalcium Aluminate

Ferrite phase: C4AF, or Tetracalcium Aluminoferrite

Bogue Compounds

Dicalcium Silicate (C2S): This compound will undergo a reaction slowly. It is responsible for the progressive strength of concrete. This is also called Belite. 

A higher percentage of C2S results in slow hardening, less heat of hydration, and great resistance to chemical attack.

Tricalcium silicate (C3S): This is also called Alite. It undergoes hydration within one week and helps in the development of strength in the early stages of concrete (aka hardening).

It has the best cementitious property among all the other Bogue's Compounds. Tricalcium Silicate (C3S) hardens rapidly and is largely responsible for the initial set and early strength.