Why is Calcium Chloride generally not permitted in admixtures?

Calcium Chloride is generally not permitted in concrete admixtures primarily because it can cause corrosion of reinforcing steel embedded in the concrete. When calcium chloride is introduced to the concrete mix, it increases the likelihood of corrosion due to the formation of chloride ions, which can penetrate the protective oxide layer on steel. This leads to a breakdown of that layer and increases the risk of rust formation, ultimately jeopardizing the integrity and longevity of the structure.

While it is true that calcium chloride can enhance the curing process, improve workability, and increase strength in certain situations, these benefits must be carefully weighed against the significant risk of corrosion. Regulatory guidelines and industry standards often restrict or prohibit the use of calcium chloride in concrete mixtures intended for structures that will be exposed to moisture or where steel reinforcement is present, to maintain structural health and safety over time.