Civil Engineering - Concrete Technology - Discussion

Option C is correct.

Presence of impurities in water for concrete mix leads to a decrease in structural properties of concrete such as strength and durability to a large extent.

The sodium and potassium carbonates cause extremely large rapid setting in large concentrations. This results in the reduction of concrete strength.

The presence of calcium chlorides accelerates the setting and hardening of the concrete. But the presence of calcium chloride is restricted to 1.5 percent of the total weight of the cement used in the mix.

Sodium carbonate and bi carbonate causes temporary hardness for this reason effect of harness and setting time of concrete.

Sodium carbonate and bicarbonate cause temporary hardness which is unfavourable for concrete mix. For this reason, it effects the strength and setting time.

As it's said impurity of water. So I think it's talk about hardness which reduces the strength.

Sodium carbonates and bicarbonates increases or decreases the setting time but how it effects on strenght I don't know.

Why not calcium chloride? It is used as accelerator.