Civil Engineering - Concrete Technology - Discussion

During the initial period of hardening, the gain in strength of C2S is small and is about 15% of that of C3S. After 28 days the hydration of C3S comes practically to an end and the hydration of C2S only really begins at that time. Hence when a high strength concrete is required within a short period of time, the cement is made with the high content of C3S. On the other hand if a high strength concrete is required at a later stage as in the case of hydraulic engineering constructions the cement is made with the high content of C2S.
So option D is the right one.

Option [A]. Finer grinding. The fineness of cement helps to improve some properties of the cement but can not impart any extra property to it and plays a role in early setting but early strength is far different.

Option [B]. Burning at high temperature...the main motives of burning are
1) to drive-off the carbon dioxide with combustion gases
2) the raw materials get fused together...
(and nothing to do with the initial strength of cement)

Option [C]. increased lime cement. Being a civil engineer, one must know this ''the lime in excess makes the cement unsound and causes the cement to expand and disintegrate and if lime is in deficiency the strength of cement is decreased and causes the cement to set quickly.

[D]. higher content of tricalcium is the correct option.

The difference of rapid-hardening cement to of ordinary Portland cement is the quantity of Limestone (tri-calcium silicate) used as raw material, which gives high early strength to the cement. It attains early strength due to a larger proportion of lime grounded finer than normal cement.

RHC develops the strength rapidly at the age of 3 days, the same at that expected in opc in 7 days. The rapid rate development of strength is due to higher fine grinding and higher of C3S and lower of C2S, but I don't know how the answer is justified to Increase in lime content.

All the options are participating in the high strength at early stage. To make RHC they are burnt at higher temperature and grinded fine.

Also increasing the lime content increases the amount of C3S. Hence all the options are correct. The answer is all of above.

Rapid Hardening Cement (RHC) are also called high early strength cement. The prime difference between the rapid hardening cement and ordinary Portland cement is the lime content. A large proportion of lime is the distinguishing feature of rapid hardening cement.

Dear sir,

The early strength of RHC is achieved by the cement is grinding finer than the OPC. So surface area of cement will more and the finer cement will quick action with water and getting early strength. If adding more cement, cement will unsound.

Friends see the options clearly.

Obviously the answer is C3S But in options it is not given (he gives only tricalcium).

C3s increase with lime content.

Answer is D.

Specific surface and burning at high temperature is next to c3s.

Its clearly written in books that the early strength of opc is due to fine grinding is responsible for its early strength. Also C3S is responsible for its early strength. So please, any body give the correct option.

First queries. What is lime cement? I am not aware about that kind of cement.

And answer should be fine grading or TriCalcium Silicate. But in question mentioned only "tricalcium".

Please give correct answer.

The rapid rate of developing of strength in RHC is attributed to.

1. Higher fineness of grinding.
2. Higher content of tricalcium (C3S) and lower content of dicalcium (C2S).

So A and D is the right answer!