How it is done
Slabjacking can both raise the old cracked slab back to its original position and create a new foundation of cement mortar or sand mix by injecting the mortar under the slab through a hole, under pressure. The viscosity of the mortar will keep it from flowing back through the hole until it sets.
Accounts of raising large concrete slabs through the use of hydraulic pressure go back almost a century. Mudjacking or slabjacking has been in common use for about 50 years. Generally a portable pump is carried to the location of the slab to be raised. A hole of up to 1.5 inches in diameter is drilled into the slab. Varying combinations of soil, sand, cement, or other materials, are mixed and then injected under the sunken concrete slab, causing it to rise.