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.
Why Does Concrete Spall?
Concrete spalling is a phenomenon that occurs in concrete structures when the concrete surface is exposed to extreme temperatures and moisture. It is a result of the physical and chemical properties of the concrete itself, as well as the environmental conditions it is exposed to. Concrete spalling is a major problem for many structures, as it weakens the structural integrity of the concrete, creates an unsightly, weakened surface, and can lead to major structural damage if not treated promptly.
The first step in understanding why concrete spalls is to understand concrete’s physical and chemical properties. Concrete is a composite material composed of cement, aggregate, and water. The cement binds the aggregate particles together, while the water increases the workability of the mixture, allowing it to fill in the gaps between the aggregate particles and form a cohesive mass. Once the concrete has set, the water evaporates, leaving behind a solid mass of interlocking grains.
Concrete spalling occurs when the surface of the concrete is exposed to extreme temperatures and moisture. As the concrete is exposed to these conditions, the water absorbs into the surface, causing the cement to expand. This expansion causes pressure to build up in the concrete, which then causes the surface to break or crack, resulting in