The cost of replacing a concrete slab is approx. double the cost of raising or levelling a slab, and it only takes between two to three hours to complete an average job. Once the levelling is finished, the slab is ready for use. There are three steps to raising a concrete slab.
Drilling: Small 5/8" holes (size of a dime) are drilled into the sinking concrete slabs to be used for injection of the polyurethane material.
Filling: A 2-part polyurethane foam is inserted below the slab via injection "ports" (which are later removed). The foam fills the space beneath the slab(s), and then expands raising the concrete to its desired level.
Sealing: Once the concrete slab is raised to the desired level, the injection "ports" are removed and the holes are filled with cement and the slab can be used immediately.