What is spalling in relation to concrete structures?

Spalling refers to the phenomenon where concrete begins to break, crack, and flake away, often due to internal pressure. This internal pressure can be caused by factors like moisture intrusion, freeze-thaw cycles, or chemical reactions occurring within the concrete, such as from corrosion of embedded steel reinforcement. When the internal pressure exceeds the tensile strength of the concrete, pieces of the surface can be dislodged, leading to visible damage such as chips or large sections breaking off. Understanding spalling is crucial for assessing the structural integrity of concrete elements and for planning appropriate maintenance or repairs.