A sunken concrete patio or driveway is not just unsightly, severe damage can make it impossible to use the space as intended. Concrete sinks due to voids that open beneath the paving, often due to washouts, uneven settling, or poor base construction. Fortunately, concrete can often be lifted back into place, so there is no need to rebuild the entire paved area. The following will answer some of your questions about the concrete lifting process.
How are the voids detected?
Your contractor will use a device called ground penetrating radar (GPR) to detect any voids beneath the concrete that are leading to the sinking and cracking of the slab. The GPR device looks like a small lawnmower with an attached screen. The contractor pushes it slowly over the concrete slab and monitors the readings on the screen. Once a void is detected, it is then marked on the slab so that the concrete techs know where to focus the lifting process.
What Is Used to Lift the Concrete?
There are two main options when lifting concrete. Mudjacking consists of a slurry of concrete mixed with polymers. The other option, Polyjacking, uses an expanding foam as opposed to the concrete slurry. Mudjacking is typically used in areas with higher traffic, thus requiring more strength, or in areas where the concrete must be lifted by more than a few inches. Polyjacking works well for areas with less severe sinking.
Will the Repair Be Noticeable?
The process of lifting the concrete does require that several quarter-sized holes are drilled into the concrete so that the foam or slurry can be injected beneath the slab in order to lift the concrete back into place. After the process is complete, these holes are filled and patched, but the small patches may still be noticeable on the driveway. Fortunately, these holes are a lot less noticeable than the initial damage was.
How Are Cracks Addressed?
Concrete often cracks as a result of sinking. Once the slab is back in place, your contractor will patch the cracks. First, a filler material is wedged into the crack. This material can expand due to thermal changes, which will help prevent further cracking. Then, a patching compound is poured into the crack and smoothed. Patches are visible on the surface of repaired concrete. In some cases, you may be able to paint the concrete or have it resurfaced in order to hide the patches from the concrete lifting and any crack repairs.
Contact a concrete lifting service for more help.