The concrete pavement in a driveway, walkway or patio can break and lift when the ground settles or roots from trees dislodge it. This can cause uneven pavement that is dangerously easy to trip on. Here are some suggestions on how to repair lifting concrete pavement.
The easiest way to repair lifting concrete pavement is to grind it down. Most driveways are at least 6" thick by code, so there should be sufficient grinding depth. Walkways and patios are 3" - 4" in thickness. Renting a scarifier is probably the most practical way to do this yourself. This is not an easy machine to use, so if you are not comfortable with the job, don't hesitate to call in a professional.
If the lifting is the result of tree root growth, you will have to grind your cement down repetitively as the roots will continue to push the concrete up. A better solution is to remove the concrete pavement all together, cut out the offending root(s) and re-pour the cement.
A quick fix would be to fill in the 'step' created by the raised concrete with a cement adhesive and concrete/polymer fill. Even if you carefully rough up the lower cement, this ramp-like fix will only be a temporary patch at best. It will chip away fairly quickly, especially on a driveway pavement with heavy traffic.
Better left to the professionals, you can float a slab of concrete that has sunk into the ground by drilling holes and pumping in a cement mix. This will literally float the slab back up with the pressure of the concrete beneath.
For more information on how to repair lifting concrete pavement, please check some of the links provided below under Additional Resources or call in your local cement contractor for advice.