The stability of any concrete surface is dependent on the soil beneath it. The weight of concrete and what it supports, combined with natural soil erosion, can lead to sunken and uneven concrete surfaces. This process affects everything from your driveway and sidewalk to roads and airport runways.
C.A.R.E. Property Services, Inc provides expert concrete repair solutions using the PolyLevel® system. PolyLevel® is an expanding polyurethane foam that is injected beneath the concrete to fill the gaps caused by soil erosion and raise and stabilize the concrete surface.
In the photos below you can see the difference that the PolyLevel creates within the before and after pictures. An obvious place to look is the top right corners of each photo.