The primary purpose of concrete lifting foam is to raise and level sunken or uneven concrete surfaces. Over time, concrete slabs used in walkways, driveways and sidewalks can settle or sink in some areas due to factors such as soil erosion, poor compaction, or changes in moisture content of the soil around them.
Concrete lifting foam also known as polyurethane foam provides an effective solution to restore and lift those sunken areas to make them even and level with the other areas that have not sunk down. It is a type of expanding foam that rises, expands and solidifies beneath the substrate, thus raising and leveling the uneven areas.
How It Works
The foam is typically made of a two-part polyurethane resin, consisting of a liquid resin component and a catalyst or hardener component. When these two components are combined, they undergo a chemical reaction known as polymerization, leading to the expansion of the foam.
As the chemical reaction takes place, the polymerization process generates gas bubbles within the mixture. These gas bubbles are responsible for the expansion of the foam. The expanding gas creates pressure, causing the foam to expand and fill the voids and gaps beneath the sunken concrete.
The expansion rate of the foam can be controlled by adjusting the formulation and the amount of catalyst used. This allows contractors to fine-tune the expansion process to achieve the desired lift and levelness of the concrete slab. The ability to control the expansion rate helps ensure precise and controlled leveling of the sunken concrete, preventing it from over lifting in certain areas.
The foam hardens after the expansion because the chemical reaction it undergoes has a closed cell structure. That simply means that the cells or bubbles formed within the foam are sealed off after the expansion, preventing any gas from escaping. This closed cell structure makes the foam buoyant, capable of carrying load like the concrete above it, and also makes it resistant to moisture and other environmental elements.
How To Use It
Concrete lifting with polyurethane foam should be done by a professional contractors with experience who can ensure proper assessment, injection, and leveling.
Here’s a step-by-step explanation of the lifting process.
Step 1: Assessment
The first thing the contractor does is to access the condition of the concrete sidewalk, walkway or any other area, and confirm if lifting will solve the issue or not. They check the extent of the sink, the stability of the underlying soil, the integrity of the concrete and determine if it can be solved with lifting or whether it should be demolished and built again with fresh concrete.
Step 2: Drilling
Once it’s determined that lifting can correct the issue, small holes around 1 inch in diameter are drilled int the sunken slab at strategic locations.
The contractor determines the number of holes to be drilled based on the size and shape of the affected area.
Step 3: Polyurethane Foam Injection
A two-part polyurethane foam, usually consisting of a liquid resin and a catalyst, is prepared by mixing the components using an injection pump. The mixture is injected through the drilled holes, as the two components come together, they react chemically, causing the foam to expand.
The liquid foam expands to fill the voids, gaps, effectively displaces any loose or unstable soil, providing support and stability to the concrete above it. This expansion exerts pressure on the sunken slab, lifting it back to its original level.
The contractor monitors the lifting progress and adjusts the injection as needed, to ensure the sunken areas lifts up and levels with the other areas.
Step 4: Curing and Hardening
After the expansion, the polyurethane concrete lifting foam hardens within a relatively short time. This provides long-lasting support and stability to the concrete above it.
Step 5: Patching and Cleanup
The final step is to patch the drilled holes and any cracks. Any excess foam is also trimmed off, the siding and holes are finished with cement and edged to blend with the surrounding concrete.
Advantages of Using Concrete Lifting Foam
It’s Cost Effective
Breaking down old concrete slabs and building new ones require more money, labor and time to construct the new ones. Polyurethane lifting foam requires fewer materials, less labor and shorter project duration.
This makes it a more affordable option for homeowners, businesses and other property owners.
It’s quick and it works
Concrete foam lifting is a relatively fast and efficient process. The foam expands and lifts the concrete almost instantly, making it possible to use the repaired surface almost immediately. It reduces downtime and inconvenience to property owners or businesses who make use of the repaired surface.
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