What is spalled concrete?

"Spalled concrete" is what happens to stamped concrete slabs as a result of snow and ice. It is the deterioration of the top layer of concrete, eventually seeping down throughout, causing flaking and scaling. While this may be the result of an improper finishing of the concrete, it can happen to any slab of concrete given enough fluctuation in extreme weather. Specifically, it is cause by water molecules infiltrating the surface of the concrete, and then freezing and thawing repeatedly; as water freezes and expands into ice, it breaks apart the concrete. Even "harmless" products like rock salt, calcium chloride, or urea may exacerbate surface spalling; these products cause rapid heating at first, but once consumed, there is the eventual refreezing that results in damage to concrete surfaces. This is because these products lower the freezing point of water, causing more frequent freeze-thaw cycling of the melted snow and ice, which causes surface spalling and scaling of concrete.