Structural Concrete Slab Repairs

Indications and Causes

• Common indications of damaged concrete slab include cracks in walls, misaligned doors and jambs, and fissures and bulges in floors, all of which result from the slab settling and throwing off the balance of the structure. This settling can be caused by a variety or combination of factors such as clay soil under the foundation expanding or shrinking, improperly mixed or compressed fill materials or poorly maintained areas surrounding the concrete slab foundation.

Pier Repairs

• Installing piers repairs concrete slabs through putting in underground supports to lift the concrete and keep it in place. The cost of using piers is about a tenth of the cost of replacing the foundation. Pier installation requires no vacation of the premises, doesn’t disrupt utility usage and no heavy equipment is used that would ruin yards or landscaping. There are two pier options and both correct the instability of the soil along with the imbalance of the structure.

Pier Options

• Push piers are pounded into the soil beneath the foundation with hydraulic rams. The piers are made from steel pipes coated with epoxy or galvanized steel. Helical piers consist of steel shafts driven into the earth with screw piles turned by a hydraulic torque motor. Both systems are anchored by rock or other weight-bearing layers under the structure that are tested for force strength prior to installation. Once the piers are in place, hydraulic jacks raise the slab back to its initial height, and it is kept stationary with brackets welded or bolted into the walls connected to the foundation.

Slabjacking Solutions

• Slabjackers use a combination of sand, cement, fly ash and other materials to pump up the foundation. The cost of the procedure is about a third of the cost of foundation replacement. The structure has to be briefly vacated, but the process is quiet, noninvasive to surrounding areas and can be performed in any type of weather. Holes between 1.5 and 2 inches in diameter are strategically drilled into the foundation. The grout mixture is slowly pumped under the slab with a similar size nozzle that fills each hole. As the grout dries and creates pressure in the cavities, the foundation is hydraulically raised to its original position. The holes are patched with concrete to complete the process.