The effect of adding calcium chloride in concrete is i) to increase shrinkage ii) to decrease shrinkage iii) to increase setting time iv) to decrease setting time The correct answer is A. (i) and (iii) B. (i) and (iv) C. (ii) and (iii) D. (ii) and (iv)

The correct answer is C. (ii) and (iii).

Calcium chloride is a common admixture used in concrete. It can be used to accelerate the setting time of concrete, increase the strength of concrete, and reduce the risk of freezing and thawing damage. However, calcium chloride can also increase the shrinkage of concrete.

The setting time of concrete is the time it takes for the concrete to harden and become strong enough to support its own weight. Calcium chloride can accelerate the setting time of concrete by increasing the rate of hydration of the cement. Hydration is the chemical reaction that occurs between cement and water to form concrete.

The strength of concrete is its ability to resist forces such as compression, tension, and shear. Calcium chloride can increase the strength of concrete by providing additional ions for the hydration reaction. These ions can also help to fill voids in the concrete, which makes it stronger.

Freezing and thawing damage can occur when concrete is exposed to repeated cycles of freezing and thawing. This damage can cause the concrete to crack and crumble. Calcium chloride can reduce the risk of freezing and thawing damage by preventing the formation of ice crystals in the concrete.

However, calcium chloride can also increase the shrinkage of concrete. Shrinkage is the decrease in the volume of concrete as it hardens. Calcium chloride can increase shrinkage by increasing the rate of hydration of the cement. This can cause the concrete to dry out and shrink more than it would without calcium chloride.

In conclusion, calcium chloride can have both positive and negative effects on concrete. It can accelerate the setting time, increase the strength, and reduce the risk of freezing and thawing damage. However, it can also increase shrinkage. The use of calcium chloride should be carefully considered to ensure that the benefits outweigh the risks.