What is 'concrete spalling' and what causes it?

Concrete spalling specifically refers to the chipping or flaking off of the concrete surface, which is primarily caused by the corrosion of embedded reinforcing steel, or rebar. When steel reinforcement inside the concrete begins to rust, it expands and exerts pressure on the surrounding concrete. This pressure can lead to cracking, and eventually, pieces of the concrete surface may break away, resulting in spalling.

This phenomenon often occurs in environments where the concrete is exposed to moisture and de-icing salts, which accelerate the corrosion process. Factors contributing to increased spalling include inadequate concrete cover over the rebar and poor-quality materials that may not provide sufficient protection against corrosion.

Understanding concrete spalling is crucial for professionals in the construction and reinforcing industry, as it reveals the importance of using proper materials and methods to protect embedded rebar and ensure the longevity and structural integrity of concrete structures.