Spalling is a term used to describe areas of concrete that have cracked and delaminated from the substrate. There are several reasons why spalling occurs including freeze-thaw cycling, the expansive effects of Alkali-Silica Reaction, or exposure to fire. However, the most common cause of spalling is the corrosion of embedded steel reinforcement bars. Corroding steel can expand up to ten times its original size, exerting stress on the surrounding concrete causing it to chip (spall).