Which chemical does corrosive inhibiting admixture contain to arrest corrosion?

Corrosion-inhibiting admixtures are designed to protect reinforcing steel in concrete from corrosion, which can significantly extend the service life of structures. Calcium nitrate is commonly used in these admixtures due to its effectiveness in reducing the corrosion rate of embedded steel. The mechanism by which calcium nitrate functions involves the formation of a protective passive layer on the surface of the steel when it is embedded in concrete. This layer acts as a barrier, preventing the ingress of chlorides and other corrosive agents that could initiate corrosion.

In addition to its corrosion-inhibiting properties, calcium nitrate also serves as a set retarder and can improve the workability of concrete. Given its dual functionality and effectiveness in combating corrosion, it is a suitable choice for inclusion in admixtures specifically aimed at enhancing the durability of concrete structures.

Other options listed do not possess the same corrosion-inhibiting characteristics. Sodium chloride, for example, is an electrolyte that can actually contribute to corrosion rather than inhibit it. Calcium sulfate and potassium phosphate are not traditionally recognized for their role in preventing corrosion in reinforced concrete. Therefore, calcium nitrate stands out as the appropriate chemical for this particular application in corrosion inhibition.