Concrete slabs that are settling or rocking can be stabilized by injecting structural polyurethane grouts into the voids beneath the slabs. Slab stabilization is accomplished when these grouts flow into the voids and cavities and fill them by expanding up to 20 times (depending on formulation). These grouts are fully expanded and traffic ready within 15 minutes (85% strength). The rigid grout re-establishes contact between the slab and the sub-grade and is strong enough for heavy traffic loads. One square foot of our structural grout will support a load of over 10,000 lbs.
Not all unstable slabs need to be lifted. Rocking slabs in traffic aisles in warehouses and factories often can be remedied via stabilization (without requiring lifting). Such rocking slabs however, if left unchecked will cause spalling of joints and possible cracking of the slab; as well as forklift tire damage and other safety hazards associated with material movement.
Slab Lifting (The Precision Lift System)
Often referred to as slab jacking or slab raising, slab lifting is the art and science of returning a concrete slab to its’ original grade. The primary cause of concrete slab failure or settling can be attributed to one or more of the following: erosion, plumbing leaks, poor drainage/run off, underslab & underground water migrations, expansive clays, poor sub-grade compaction, or improper fill materials & biodegradable materials in the sub-grade. Left unattended, water flow (rain, drainage, etc.) will often continue to cause ongoing erosion and wash outs; thereby creating larger voids and an unstable sub-grade, which can greatly amplify the original problem. If unchecked, erosion can cause devastating damage and grave safety hazards.
Once the cause has been determined the proper repair methodology and materials can be combined to effect the repair. Simply put, slab lifting involves the process of injecting a 2-part polyurethane structural grout though the concrete under pressure via ports inserted in 3/8” drill holes. This material will flow into the voids and cavities under the slab, and fill them by expanding up to 20 times (depending on formulation). As the grout reacts and begins to expand, the slab will begin to raise. Because we lift very slowly and with the aid of laser levels placed strategically on the slab being lifted, we accomplish a near level slab (or back to original grade) under most conditions. This process also seals any concrete cracks that were present; which may help to eliminate further water intrusion and subsequent erosion.
After the slab is lifted to the desired, pre-determined position, all injection holes are filled with cement. The only remaining evidence of the repair will be the 3/8” injection holes. This is much more aesthetically pleasing than partial rip-out-and-replace slab methods (which can look piecemeal when compared to surfaces outside the immediate area of repair).
We specialize in lifting entire concrete structures, buildings & foundations, both interior and exterior concrete floors, concrete aprons, highway-bridge approach slabs, sidewalks, stairs & steps, patios, driveways & roads, pool decks, etc. The Precision Lift System permanently and safely remedies unsightly sunken concrete and removes trip hazards, standing water and areas of erosion.
All of these problems and a whole lot more can be quickly repaired and usually brought back to original grade in hours……not days and weeks. The areas are also typically ready for use immediately, and slab lifting is far less intrusive and costly than traditional rip out and replace methods.
It should be noted that the root cause should never be ignored; and that items such as drainage, leaky pipes, or weak and unstable soils should be remedied, if required.