There are two options for leveling concrete slabs.
Mudjacking uses a grout which is comprised of sand and cement. The process requires a 1" to 2” diameter hole to be drilled through the slab and then the grout is pumped into the hole and under the slab to be lifted.
The other option is to use Polyurethane Foam Injection. This method requires a 5/8” diameter hole to be drilled then the Polyurethane Foam is injected under the slab.
Both methods are designed to accomplish the same results.