Civil Engineering - Concrete Technology - Discussion

Many chemical admixtures are known to retard cement hydration.

I agree @Faraz.

Answer is A. Because hydration process depends only on water content and temperature but not on admixtures.

There will be no hydration if we add admixture in mix in absence of water or at the low temperature because the hydration is the chemical reaction which is directly initiated by temperature and water.

Admixture never gives strength.

I think D is the correct answer.

The answer should be E as there are some admixtures that accelerate hydration.

The Answer should be D.

Admixture never gives strength it only accelerate the rate of gain of strength.

Admixture can accelerate the rate of hydration.

So, Option E correct.

Admixture never gives strength.

The Option A is Correct.

These admixtures are used for following purposes:

1) To achieve a higher strength by decreasing the water cement ratio at the same workability as an admixture free mix.

2) To achieve the same workability by decreasing the cement content so as to reduce the heat of hydration in mass concrete.

3) To increase the workability so as to ease placing in accessible locations, Water reduction more than 5% but less than 12%.

4) The commonly used admixtures are Ligno-sulphonates and hydrocarboxylic acid salts.