Corrective controls are the actions you take to recover from an incident. You may lose a hard drive that contained data; in that case, you would replace the data from a backup you had previously taken.
Fire-suppression systems are another form of corrective control. You may have had a fire in your data center that has destroyed many servers, therefore when you purchase a replacement, you may install an oxygen-suppressant system. This method uses argon/nitrogen and sometimes a small element of CO2 to displace the oxygen in the server room. The basis of this method is to reduce the oxygen level to below 15% because it will suppress a fire.