Steel Corrosion in Concrete due to Calcium Chloride Accelerators

Why Use Calcium Chloride in Concrete?

The primary purpose of adding calcium chloride to a concrete mix design is to increase the rate of the curing process. During hot summer months concrete sets very quickly and calcium chloride is typically not necessary. During periods of cold weather, however, concrete takes much longer to set. Calcium chloride accelerators are much more beneficial in this scenario to the finishing process and early age strength of the concrete. Unfortunately, this may create an issue if there is reinforcing steel in the concrete.

Effects of Calcium Chloride on Steel

Studies show that calcium chloride increases the rate of corrosion in steel. This will lead to the deterioration of the reinforcing steel and ultimately result in spalling and cracks on the concrete surface. For this reason, it is best to avoid calcium chloride accelerators in applications in which rebar will be used.

Other Concrete Accelerating Solutions

A simple answer to this problem is to use Non-Chloride Accelerators (NCA’s) in your concrete. NCA’s will increase the rate of hydration in the concrete and speed up the finishing process while reducing the likelihood of corrosion occurring due to the presence of reinforcing steel. Although NCA is standard among many concrete suppliers, calcium chloride is a cheaper alternative that can still be found within the industry. It is always best to ask and ensure that calcium chloride will not be used by any concrete contractor performing a project on your home to ensure the longevity of your concrete product!