Raising Concrete with Confidence
When pumping a light-weight material beneath a slab, you need the confidence that it is
strong enough for the application. How strong is strong enough? This is a commonly asked question by engineers that are new to slab jacking with polyurethane. Structural foams only need to be as
strong as dirt, but they're actually stronger than crystalline bedrock.
The Right Strengths for Concrete Lifting
Slab lifting foams are rated on density (weight per cubic feet) and compressive
strength. This testing and rating is based on the foam in a free rise state; the parts A and B are mixed together and allowed to expand freely. Our structural lifting foams, for example, will weigh
2.75 – 3.25 lbs to 4.75 – 5 lbs per cubic foot. But they have a compressive strengths of 50 psi and 100 psi in a free rise state. That's equal to 7,200 to14,000 lbs per square ft of support,
just in a free rise state.
Polyurethane Slab Jacking Compared to Clay and
To put that into perspective, the National Home Builders Association and the
International Building Code lists stiff clay at 4000 psf and crystalline bedrock as having 12000 psf of load bearing capacity. Consider the job site conditions where the foam will be injected into a
confined area. Testing data in the lab shows that our lifting foams will increase in compressive strength: In a space confined 25% by volume there will be an increase of 31% in psi and in a space
confined by 75% there will be a 79% increase in the psi.
Slab Jack for Any Job with the Right Foam
Today polyurethane lifting foams are used to level airport slabs supporting jumbo jets,
equipment and building slabs supporting tremendous loads, and even railway sleepers that support the heaviest freight trains. So don't let the word “foam” fool you. These resins cure to strengths
beyond what is needed to support any structure.