Our polyurethane foam method uses the concrete slab itself as a means of delivering poly foams that raise concrete, fill voids, and stabilize soils. A ⅝” hole is drilled through the slab into the subgrade. A tapered delivery port is installed into the ⅝” hole. The injection gun is connected to the port. The injection gun delivers the polyurethane material through the port and slab. Expansion of the material occurs within seconds, compressing loose soils and raising concrete.