What effect does calcium chloride have on concrete?

Calcium chloride is commonly used as an accelerator in concrete mixtures. Its primary effect is to decrease the set time of concrete, allowing it to harden faster. This can be beneficial in construction, especially in colder weather conditions where the curing process can be slowed down. By adding calcium chloride, the initial and final set times of the concrete are reduced, facilitating earlier finishing and loading of the concrete.

It's important to note that while calcium chloride is effective in accelerating the setting time, it should be used judiciously as excess amounts can lead to issues like efflorescence or corrosion of steel reinforcement. However, in the context of this question, the focus is on its primary role as a setting accelerator, validating the choice that it decreases the set time of concrete.