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Slab Lifting

Mountain Grout Flexible

Slab lifting is the process of pumping voids beneath failing, sinking slabs with polyurethane resin and using the expansive properties of the resulting foam to support and lift the slab to its proper level. Single component polyurethane resins or dual component polyurethane resins can be used depending on specific site conditions and pumps available to the installer.

If installers prefer a single component, Mountain Grout Flexible is most often recommended due to the strong, robust foam it creates. If a dual component is required, Mountain Grout Void Filler or Mountain Grout U4.0 are the two most likely recommendations. A successful application lifts the slab to its original level and guards against further erosion of the soils beneath the slab. The cured foam can support the slab for everything from light foot traffic to heavy equipment and highway vehicles.

Installers pump the polyurethane foam of their choice through a removable injection port, or packer, which is installed into the slab using a drill bit. Pumping the product under pressure and the expansive properties of the foam enables it to spread and penetrateand fill everything from large spaces to tiny voids. The polyurethane foam reacts and starts to expand and the slab begins to rise.

Installers should be careful to pump the resin at a slow and controlled rate to avoid causing damage to the slab. Some bore holes drilled for packers should be left open to allow pressure created by the reaction to release. Installers can also use these vacant bore holes to monitor the travel of the foam under the slab to help determine the proper volume to pump.

The foam is created by the chemical reaction of the resin and catalyst and will expand at a rate of 15 to 30times its original volume, depending on specific site conditions. After the slab has been lifted, the ports should be removed and the injection holes should befilled with nonshrink grout.

Any foam that escapes from joints or slab edges should be scraped off. Most slabs can be restored to their original elevations or sloped grades and, now supported by polyurethane, will stand the test of time.

Common Application Sites:

  • Highways
  • Factory Floors
  • Concrete Slabs
  • Sidewalks
  • Driveways
  • Pool
  • Decks
  • Foundations
  • Basement Floors
  • Loading Dock Slabs
  • Concrete Patios
  • Warehouses

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Green Mountain Grout International LLC, Member of the ICRI & Member of the ASDSO.