Welcome to the concrete floor leveling pages of ConcreteJack.com. Concrete Jack is a concrete leveling contractor serving Virginia and North Carolina which repairs settled and uneven slab on grade floors, in addition to other concrete flatwork. Concrete Jack’s concrete leveling process, which is also known as slab jacking, mud jacking, concrete raising and pressure grouting, works by injecting material under concrete to fill any voids and then raise the concrete back to its original level.
Concrete Jack uses three different materials to repair floors which have voids under them or have settled. The first is a sand-based grout, comprised of 70 percent sand and 30 percent clay, which we can also add Portland cement to as a drying or hardening agent. The second material is a group of expanding polyurethane foams, different types of which can expand to as much as 20 times from their liquid volume to others which expand as little as three times their liquid volume. The last material is lightweight cellular concrete, which is a great product for large void fills that do not require lifting or leveling work.
Lifting With Polyurethane Foam and Grout
The lifting process uses either high expansion polyurethane foam or sand-based grout to fill any voids under the floor and then push the concrete up. For grout, it is the force of the grout pump that pushes the concrete up, at a low pressure, of around 10 to 20 pounds per square inch. For the foam, it is the physical expansion of the foam that pushes the concrete up. Both materials work quite well, though the polyurethane weighs less and does better with smaller voids, so in areas where additional loading of subsoil is a concern, it usually the best material. Polyurethane does not do well with deep voids, because the material is more expensive and also generates heat in the reaction process. All of Concrete Jack’s jobs are evaluated by qualified estimators and project managers, who can help you in weighing the benefits of each material and selecting the repair method best suited to your settlement problem.
Micro Void Filling With Polyurethane Foam
For small and micro voids, such as those associated with slab curl, the low-expansion polyurethane foam material is best. It can flow into voids as small as 1/64 of an inch to stabilize loose soils and ensure proper contact between the bottom of slabs and the top of the base material.
Deep Void Filling with Lightweight Cellular Concrete
For deep voids or those where the floor has not started to settle, lightweight cellular concrete is often the best option. The material flows very far—it can easily travel 200 feet in all directions from a single injection point without segregation, which ensures a uniform fill. The material is also very light—1000 pound per square foot compressive strengths can be achieved with densities of just 30 pounds per cubic foot. Lightweight cellular cement can also be used to fill large voids under settled concrete in preparation for lifting using polyurethane foam or soil-based grout. This process works by filling voids up to very close to the bottom of the floor slab, letting the cellular concrete cure over a short period, and then coming back through with either foam or grout to inject into the smaller void to push the floor back up to level.
Concrete Jack’s crews have raise all types of floors, from small residential garages to 1600 square foot slab on grade homes with settlement extending up into upper floors. On the commercial and industrial side, we have raising floors inside of nursing homes and manufacturing facilities. The nursing home floor repair was particularly challenging in that it was inside of the dining room of a building occupied more than 60 percent by wheel-chair bound residents. The floor had settled along an exterior wall, so Concrete Jack’s crews inserted steel needles through the CMU exterior wall below the bottom of the slab and injected the grout material through the needles into the space under the floor. This pushed the floor back while maintaining full utilization of the facility; lifting was conducted during all three meals of the day. Concrete Jack also raised the floor of the facility’s Chief Financial Officer using the same process the following year after it began to suffer the same problem (different building and construction time).
Concrete Jack recently used lightweight cellular concrete to void fill under the foam and stainless steel floor of a built-in hospital freezer. The freezer was installed over a depressed area the in the floor and was supported by lathe strips, which caused the floor panels to deflect and deteriorate. Concrete Jack pumped lightweight cellular concrete more than 200 feet through interior hallways and food storage areas and then injected the material under the floor. This solution saved thousands of dollars of lost productivity that would have accompanied a floor replacement or other repair. Because lightweight cellular concrete does not segregate during pumping (it is a neat mixture of only water and Portland cement along with the foaming agent), the owner of the freezer and the freezer installation contractor were both totally confident that Concrete Jack’s value-engineered solution was the best and most permanent.