Whenever a concrete surface is not completely level, there is a risk for damage due to the accumulation of water. After a rainfall, puddles can often form in spots that are not level on a concrete surface, and the same can happen on concrete basement floors that have been flooded. After several years of such puddling, the integrity of the concrete can become compromised. You can, however, patch these indentations to reduce the chance of damage.
Things You'll Need
Concrete patching compound
Straightedge (spare piece of wood)
Clean the concrete surface. You want to clean the depression in the concrete first with water and a wire brush. Scrub the surface to remove dirt and grime and allow the depression to fully dry before applying compound.
Mix a concrete patching compound. In a bucket, mix the dry patching compound with the liquid recommended on the packaging. In many cases this is water. Strictly follow the guidelines on the package to achieve the desired consistency of the mixture.
Pour the compound into the depression on the concrete surface so that it is slightly mounded above the surface of the surrounding concrete.
Use a spare piece of wood to level the compound with the surrounding concrete. The piece of wood should be long enough so that its ends slide along the concrete, while the middle levels out the compound.
Smooth the surface of the compound and more finely integrate the edges with a metal trowel.
Let the compound dry for 24 hours before disturbing it.