Concrete is a mixture of cement, sand, and gravel. It is a building material that is used in the construction of buildings and other structures.

There are two types of concrete damage:

1) Concrete spalling - this occurs when the surface layer of concrete starts to break apart or chip off. The cause for this type of damage can be due to environmental factors such as freezing or thawing cycles, or it can be caused by chemical reactions with acidic materials such as sulfates.

2) Concrete erosion - this occurs when water seeps through cracks in the concrete and starts to break down the surface layer. This type of damage can also be caused by environmental factors such as freezing or thawing cycles, but it can also be caused by chemical reactions with acidic materials such as sulfates.