Rain Damage to Concrete Slabs

Rain and Concrete

It may come as a surprise that rain can be problematic for concrete. Sometimes, rainfall can actually benefit concrete — concrete mix water is unlikely to evaporate in the high humidity that occurs during rainfall. However, excessive rainfall collected on the surface of the concrete can alter the water to cement ratio, changing the concrete's durability if the water is allowed to dry with the concrete.

The simplest way to prevent concrete damage from rainfall is to cover the concrete with plastic sheeting. The only disadvantage to this technique is that pelting rain can physically alter the texture of the concrete as it dries, but this is merely a cosmetic rather than a structural problem. Steel or wood side forms should also be on hand to prevent the rain from altering the shape of the concrete, and the plastic sheeting should be weighed down so it is not blown about by the wind.

Of course, rainfall can be unexpected, or it can occur when the concrete job site is unattended. In these instances, it is necessary to visually inspect the concrete to assess the degree of damage. There are several methods for doing so, but they can be complex and may be difficult for anyone without extensive experience as a construction worker. Simply consider the rainfall itself to assess the degree of damage to your cement; if the rainfall was hard enough to alter the surface texture of the concrete, the concrete likely will not need to be replaced. It is only in exceedingly rare circumstances of particularly forceful rainfall that damage to concrete will be so excessive as to warrant removal and replacement.

For cosmetic or for any other reasons, you may still wish to repair whatever damage the rainfall has caused on your concrete. Diamond grinding can smooth out the differences in texture caused by rainfall impacting poured concrete. Keep in mind, however, that by diamond grinding, you are removing height from the concrete, so it will typically be necessary to measure the concrete after grinding to make sure the concrete still meets the minimum height required by your construction project.