What is polyjacking and how does it differ from regular polyurethane injection?

Polyjacking is the trade term for concrete lifting using expanding two-part polyurethane foam and the terms are interchangeable with polyurethane foam injection. The foam is injected as a liquid through small ports in the slab, where it expands 20 to 30 times its liquid volume, fills the void, and lifts the slab as it expands. The result is a lightweight water-resistant fill that cures in 15 minutes.