Civil Engineering - Building Materials - Discussion

The setting and hardenings of cement paste is mainly due to the hydration and hydrolysis.

Give ans is right.

Here asked about initial setting, not asked speeds the setting. Kindly read the que again.

Option A is the correct answer.

C3A is responsible for both flash and initial setting time.

C3S and C2S for strength and C3A for the early setting of cement.

C3S for initial setting.
C3A for the flash setting.
C2s for Ultimate strength.

The Answer is right because it is asking the for the early setting time of cement which is due to tricalcium aluminate but for the early strength of cement, tricalcium silicate and ultimate strength or final strength is due to dicalcium silicate. So don't be confused be clear.

Properties of cement compounds These compounds contribute to the properties of cement in different ways

Tricalcium silicate, C3S:- This compound hydrates and hardens rapidly. It is largely responsible for portland cement's initial set and early strength gain.

Dicalcium silicate, C2S:- C2S hydrates and hardens slowly. It is largely responsible for strength gain after one week.

Tricalcium aluminate, C3A:- It liberates a lot of heat during the early stages of hydration, but has little strength contribution. Gypsum slows down the hydration rate of C3A. Cement low in C3A is sulphate resistant.

Tetracalcium alumino Ferrite, C4AF:- This is a fluxing agent which reduces the melting temperature of the raw materials in the kiln (from 1650o C to 1450o C). It hydrates rapidly but does not contribute much to the strength of the cement paste. By mixing these compounds appropriately, manufacturers can produce different types of cement to suit several construction environments.

C3S is correct.

C3S is responsible to early strength not early setting time, C3A is responsiblefor early setting time.