What is Polyurethane Foam Concrete Lifting?
Injection holes are strategically drilled into the concrete slab(s) that requires lifting. The equipment is contained in a trailer rig with a long hose capable of reaching direct to the concrete slab location. Polyurethane foam is then injected under the slab filling voids, and raising it to the correct level.
After the injection is completed, the hole is patched with polymer concrete or cement. The concrete slab is repaired and for immediate use. The concrete repair typically takes a 1-2 hours based on the scope of your project. Most jobs can be done in one day.
Watch this video showing how SPF can be injected beneath a damaged concrete sidewalk to eliminate a dangerous trip hazard.
video courtesy Elite Concrete Lifters (VA)
Polyurethane concrete raising achieves the same results as traditional mudjacking, but with a lightweight material that requires smaller and fewer injection holes. Also known as foam lifting, polyurethane concrete raising is the latest and greatest concrete repair method available.
What are the Benefits?
Polyurethane foam concrete raising is a cost-effective alternative to replacing concrete. Concrete raising can usually be done for less than half the cost of pouring new concrete. However, the savings may be even greater, since when concrete raising the costs of demolition, removal, and landscaping are eliminated.
Polyurethane foam concrete lifting and stabilization avoid costly tear out and disruptive replacement of the slab. This allows the surrounding area to remain in use or service even during the project with minimal downtime, if any.
Quick Cure Time
Polyurethane typically cures in minutes after injection allowing areas to be fully available in minutes not days.
Since the foam cures in minutes—most solutions exhibit 90% of full compression strength after 15 minutes—large surface areas can be lifted and returned to service immediately during the application. This allows for swift construction and minimal waste.
The ease of application contributes to less time working, as does the fact that many of our geotechnical foam solutions can be applied by a two-man crew. These factors all translate to fewer paid man hours, and lower overall job costs.
Our geotechnical foam solutions are designed to be built up in great lift thickness without scorching or foam splitting. During application, our systems have low exotherm heat transfer, which eliminates additional spray passes and ensures quick construction.
Moisture-Tolerant and Resistant
Though our solutions are injected into wet areas, they will maintain their physical characteristics during reaction and expansion. Plus, the high-density, closed-cell nature of geotechnical foam makes them resistant to water penetration
Geotechnical polyurethane foam is designed specifically for different concrete applications. Theses foams are environmentally friendly, consisting of 39-49% renewable and recycled materials. In addition, polyurethane concrete lifting reduces the environmental impacts of concrete disposal and replacement.
Concrete Lifting Process
At its core, polyurethane is a two-component fluid material made up of a A-side and B-side. The materials are pumped to a proportioner that heats and pressurizes the material to a 1:1 ratio, then it is pumped through a heated hose to the application gun where the two materials are mixed and begin to become polyurethane foam.
The two chemicals begin to react, increase in volume 30-40 times their original volume and develop into a foam. This development of the foam is what lifts concrete.The foam pushes against the substrate and concrete. Since the resistance of the substrate is greater than the resistance of the concrete, the concrete slab begins to raise. It is through experience and thorough understanding of construction methods that the technician can inject the appropriate amount of material to perfectly raise and level the sunken concrete.
A contractor who specializes in lifting and leveling concrete will have all the specialty equipment to properly process the polyurethane foam including:
- Air Compressor
- Foam Hose
- Application Gun
- Ancillary Tools Necessary to Work with Concrete
Once on-site, the contractor will strategically drill 5/8” diameter holes into the areas that need lifted and leveled. Multiple injection holes are required even for the smallest applications.
Application ports will be installed into the drilled holes, and the application gun will be attached to the ports, this is when the injection of the polyurethane foam can begin.
Once the valve/trigger on the gun is actuated, the polyurethane foam enters the underside of the concrete and begins to spread out in a 3’ diameter circle. The chemical reaction of the A and B side begins, and the foam increases in volume 30-40 times its original mass. The reaction and growth of the foam is what causes the concrete slab to lift. There are primary holes that develop the lift and secondary holes that are used to fill the void that is created adjacent to the “pillows” that are created through the lifting process. Without filling the voids, the concrete can be compromised or prone to additional cracking as there would be areas of the slab that are cantilevered without the proper substrate support.
- STEP 1: Injection holes are strategically drilled around the areas where the concrete is sunken and requires lifting.
- STEP 2: Polyurethane foam is injected through the holes which fill the space underneath the concrete slab, using the concrete slab itself to drive the foam into the crevices, thereby lifting the concrete back to its original, correct level.
- STEP 3: Once concrete is leveled, the injection holes are filled discretely with new cement, allowing you to use your surface immediately.
Concrete Mudjacking vs. Foam Concrete Lifting
The initial technology utilized “mud” to jack the concrete up and while effective, it is disruptive, messy and not necessarily the best long-term solution. As the industry evolved, the most successful competition for “mud” jacking was polyurethane foam technology. Polyurethane foam developed in the early 1960’s began to take a large foothold in numerous industries including insulation, roofing and just about everything that has a foam pad or cushion in it.
As the chemistry advanced, the applications for polyurethane foam grew dramatically. As the equipment technology caught up with the chemical technology, polyurethane foam began to be used in lieu of “mud” jacking for concrete lifting and leveling.