One of the fastest growing segments of the foam industry is Poly Jacking. Poly Jacking refers to the process that uses special polyurethane foam to lift and level concrete. There is a wide market for these services including homeowners and residential markets, municipalities and industrial applications. The basic process involves drilling holes in the strategic areas on the non-level concrete and pumping in special expanding polyurethane foam to raise the concrete back to its appropriate level. 10 psi will lift a standard free floating slab of concrete. The foam needs to lift the concrete but shouldn’t adhere to it. As the concrete slab needs to be raised one side at a time, when you raise one side, you may end up lowering the other. But this can be beneficial because rocking back on foam already installed is important, but nearly impossible if the foam becomes too rigid or hard too quickly. The foam needs to remain pliable long enough to work with it as you raise and level the slab. Good foam should set up in 15-20 seconds and stay pliable for 15-20 minutes. 
