Polyjacking can be a permanent solution to sunken concrete if you also address the underlying issue—like poor drainage—at the same time. The polyurethane material itself can last as long as or even outlast the concrete you’re lifting it with. Your sunken concrete issue will likely return if you don’t couple polyjacking with proper drainage to prevent future soil movement and sinking.

A sinking foundation can be lifted, most often by installing piers to re-level and support the weight of the house. Depending on the cause and extent of the sinking, other methods to lift a foundation include underpinning and mudjacking. Consult a foundation repair pro to determine the best way to lift your sinking foundation. 

Mudjacking typically takes 24 to 72 hours (one to three days) to dry and cure completely before you can resume normal use. The exact time can vary depending on the size of the project. Because the slurry mixture contains cement, it must fully harden to ensure that added weight from walking, furniture, or vehicles won't shift the concrete slab. A professional contractor can advise you on when the surface is safe to use. For comparison, if you use polyjacking instead, the polyurethane foam can dry in just a few minutes, but it's best to wait about an hour before use.

On average, a mudjacking repair lasts between five and 10 years, though it can sometimes last for well beyond a decade under ideal conditions. Its longevity depends heavily on several factors, including the condition of the underlying soil, environmental conditions like freeze/thaw cycles and erosion, and whether the root cause of the sinking, such as drainage issues, is resolved. Because it doesn't always fix the underlying problem of loose soil, mudjacking is often considered a temporary solution. Proper maintenance and evaluation can help extend its lifespan.