We begin by injecting the two-part polyurethane foam through a removable injection port that is installed into the slab using a 5/8" drill bit. The foam is capable of spreading and penetrating voids as small as 1/32 of an inch. The two part foam reacts and starts to expand and the slab begins to raise. This is done at a slow and controlled rate, often referred to as the "art and science" of concrete lifting. The foam is created by the chemical reaction of the resin and catalyst and will expand at a rate of 15 times its original volume. We monitor the lifting slabs with the aid of laser levels and dial indicators as well as box beam levels. Most slabs can be restored to their original elevations or sloped grades. During the lifting process, slabs may crack. Cracks due to settlement may lose up because they are being restored to proper grade.
After the slab has been lifted, the ports are removed, the injection holes are filled with non-shrink grout. Any foam that escaped from joints or slab edges is scraped away and disposed of and the only evidence of our repair is the grouted 5/8" ports.
A pattern of holes are drilled through the sunken slab.
Polyurethane material is pumped under the slab filling all voids and raising it to the desired height.
The holes are then patched with cement.
Trade names such as slab jacking, poly lifting or slab raising, slab lifting is a method of returning a concrete slab to its original grade. Concrete slab failure or settling often times is not due to the concrete itself but can be attributed to one or more of the following, erosion, expansive clays, poor sub-grade compaction or biodegradable materials in sub-grade. Left unattended water flow (rain, drainage, etc.) will continue to wash away this base creating voids and unstable sub-grade which amplify the failure.
Once the cause has been determined the proper repair methodology and product can be combined to effect the repair. We will then begin the injection of a 2-part Polyurethane Foam via 5/8″ ports capable of penetrating voids as small as 1/32”. As the foam 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 perfectly level slab (or back to original grade if sloped) under most conditions. This process also seals any cracks that were present 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 grouted 5/8” injection holes. This is much more aesthetically pleasing than rip-out-and-replace slab methods that can be discolored when compared to surfaces outside the immediate area of repair.
We specialize in raising concrete floors, squares, walk paths, patios, driveways and pool decks to permanently and safely remedy unsightly sunken concrete and remove trip hazards, standing water and areas of erosion.
CASE STUDY: NCFI’s TerraThane™ Helps Improve Houston’s Busy Highways
CASE STUDY: Soil Beneath Historic Landmark, The American Royal, Erodes and Concrete Slab Floor Becomes Uneven
CASE STUDY: Convention Center Built on Reclaimed Riverbed Suffers from Settling, Erosion, and Construction Issues. Contractor Uses TerraThane™ to Fill Voids, and Raise and Level Concrete Slabs.
Lifting an underground manhole junction? Re-leveling a basketball court? Is your living room floor beginning to settle and separate? Seawall showing signs of stress? Concrete roadway beginning to get bumpy? Warehouse floor showing stress?
All of these problems and a whole lot more can be quickly repaired and brought back to original grade in hours… not days, and in most cases are ready for immediate use under load.This process is EXTREMELY clean… no big pumps and nasty concrete slurry puddles. In fact, only the small, filled injection holes bear evidence of a previous repair.