MUDJACKING & POLYURETHANE FOAM LIFTING
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If you’re searching for mudjacking or void fill, you probably have a sinking concrete foundation or even sidewalks and driveways. Uneven concrete slabs such as sidewalks, driveways, pools or pool decks, patios, and floors are not only eyesores, they’re also a safety liability that could result in injuries and even lawsuits.
The old school technique of fixing uneven concrete slabs was to simply dig them up and replace them by pouring new concrete. This was both expensive and time consuming. There was also the downtime waiting for the new slab to dry and harden.
Therefore, raising the slab became a better option, first via a technique called mudjacking and later via polyurethane foam injection. Both techniques involve drilling holes into the slab and then injecting a material to fill the voids and lift the slab.
WHY DO CONCRETE SLABS SINK AND BECOME UNEVEN?
Concrete slabs sink for a variety of reasons including problems with drainage, expansive tree roots, and expansive soil.
Expansive soil is soil that swells when it gets wet, and shrinks when it dries out. This back and forth swelling and shrinking is seasonal and causes the soil to move. This can, over time, destabilize any concrete slab sitting on top of expansive soil.
Drainage problems can cause too much water to get under the slab and wash away the soil holding it up. Voids form and the slab starts to sink.
You can probably visualize how expansive tree roots can destabilize a concrete slab such as a sidewalk. Not only can they physically push against the slab, but they can also soak up moisture from the soil causing it to shrink and eventually leading to the formation of voids under the slab.
WHAT IS MUDJACKING?
Mudjacking has been around for about 75 years now, and is used to lift everything from Slab home foundations to small sections of sidewalk. It’s a quick repair and can often be completed in just a few hours or days depending on the size of your project.
Note: Mudjacking is used to lift and level concrete slabs, mudjacking is used to raise intact concrete slabs.
If a slab has been severely damaged, mudjacking won’t help. The slab will need to be torn up and replaced with a new one.
HOW MUDJACKING WORKS?
Mudjacking involves drilling several holes – about 1.5”-2.5’’ in diameter – into the slab. A cement slurry usually consisting of water, sand, and portland cement is then injected under the slab via the core holes. It fills any voids and as the pressure builds, it lifts the slab back up to where it was before. The holes are then filled to match the existing grade, and the repair is complete. Once the concrete has cured properly – this usually takes 12 hours – the slab will be ready for use again.
THE PROS AND CONS OF MUDJACKING
- Mudjacking is less expensive than replacing the concrete slab because you don’t need to remove the old slab and pour a new one.
- Mudjacking is an environmentally-friendly green solution because the slurry injected under the concrete is a mix of water, sand and cement.
- Mudjacking is a quick repair. Most jobs can be completed in just a few hours.
- Mudjacking is an easy repair that doesn’t require any heavy equipment or a large crew.
- The holes required for mudjacking are larger than those required for polyurethane foam injection because the cement slurry is bulky.
- The cement slurry used in mudjacking is also heavy. If the slab sunk because the soil wasn’t able to support it, adding even more weight isn’t going to help. In fact, it could even cause the slab to further sink into the ground because of the added weight. (The cementitious mud used for mudjacking typically weighs from 90 to 125 lbs./cubic foot.)
ABOUT FOAM INJECTION
- Polyurethane foam injection started being used back in the 1980s to repair/fill voids in roads and highways. Today, it’s still used to repair roads, but also sidewalks, driveways, pool decks, patios, sinkholes and more. If you need to lift a sunken concrete slab, polyurethane foam injection is also a good solution
- It’s a minimally-invasive procedure that does not require digging or excavation.
- While both mudjacking and polyurethane foam injection require drilling holes in the concrete, the holes necessary for polyurethane foam injection are smaller, only around 5/8’’ in diameter compared to the 1.5”-2.5’’ holes necessary for mudjacking.
- Polyurethane foam is extremely lightweight when compared to the heavy cement slurry used in mudjacking. The unit weight for polyurethane grout typically used for slab lifting ranges from 2.0 to 6.0 lbs./cubic foot.
- Around 15 minutes after the polyurethane foam injection procedure is complete, the slab is ready for use again. In contrast, you’ll need to wait about 24 hours to use the slab again after mudjacking.
- Polyurethane foam is under the slab to stay. It will not wash away, shrink, or lose its density and bonds well to soil particles.
- While polyurethane foam injection does cost more than mudjacking, it’s less expensive than tearing up a slab and replacing it with a new one. Also, like mudjacking, polyurethane foam is an environmentally-friendly green solution.
HOW DOES POLYURETHANE FOAM INJECTION WORK?
Polyurethane foam injection is a simple, 3-step process:
1. Small, 5/8 inch diameter holes – strategically placed – are drilled in the concrete slab.
2. The polyurethane foam is injected into the holes in order to lift the concrete slab back up to where it was before. The foam is pumped in as a liquid, but then rapidly expands in order to fill the voids and raise the slab.
3. The holes are filled, and in about 15 minutes the slab will be ready for use again
Tearing up a sunken concrete slab and then replacing it by pouring new concrete is expensive and time-consuming. Therefore, repairing an intact slab is always going to be the better option. The question then is, which is better, mudjacking or polyurethane foam injection?
While mudjacking is less expensive than replacing a concrete slab, it has some serious drawbacks, including the fact that adding more heavy cement to soil that’s already having trouble supporting a slab isn’t going to solve the problem. In fact, it could make it worse. This is why we recommend polyurethane foam injection for raising sunken concrete slabs.
Have a sunken concrete slab that needs lifting and leveling? We are a Texas Based company but we serve all over the united states, Please Contact us today for an inspection and estimate at (817) 226-7221