Learn about the advantages and disadvantages of leveling your settled concrete with foam.
If you’re tired of looking at your old, settled concrete, professionally leveling the sunken concrete slabs may be just what you need to bring it back to life.
Concrete leveling is a great way to restore concrete for an affordable price, and there are a few different methods for getting the job done right – foam injection, traditional mudjacking, and stone slurry grout concrete leveling.
Each method comes with its own advantages and disadvantages, and it can be tricky to decide exactly which route to take.
To help you decide which method is right for you, we’ve created this article detailing the pros and cons of foam concrete lifting based on our 30+ years of experience in the concrete leveling industry.
How Does Foam Concrete Leveling Work?
Before diving into the pros & cons of foam concrete leveling (also called “polyjacking”), let’s start with a refresher on how it works.
It follows the same steps as other concrete leveling methods but uses expanding polyurethane foam to lift the slabs:
- Holes ~⅝ inches in diameter are drilled in the settled slabs.
- The liquid foam is injected through the holes and undergoes a chemical reaction underneath the concrete that causes it to expand and lift the slab.
- Once the slab is lifted back into the right position, the drill holes are patched.
Pros & Cons of Polyjacking Overview
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Pros of Foam Leveling
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Easy To Transport
The foam used in foam concrete lifting starts out as a two-part liquid and expands under the concrete as the two combine.
This liquid takes up less space compared to the pulverized stone or mud used in other concrete leveling methods, making it easier to transport and carry more material for high-volume jobs.
Additionally, foam concrete lifting can sometimes be done with portable units. This is ideal for hard-to-reach areas that would be inaccessible with the hoses used in stone slurry leveling or the traditional mudjacking process.
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Cures Quickly
Most polyurethane foam products used in the polyjacking process reach an initial cure within one hour of injection.
It may take longer to cure completely depending on the chemical formulation, but this quick initial cure allows the concrete slabs to be used right away.
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Cost-Effective Alternative to Replacement
Like all concrete leveling methods, polyurethane foam concrete leveling can save quite a bit of money off the cost of replacement.
This is because concrete lifting requires far less time, labor, and materials than completely replacing the concrete. There’s no need for demolition, and most concrete leveling repairs are completed within a day.
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Small Drill Holes
Foam concrete leveling can be done with smaller drill holes (~⅝ inches) that may be less noticeable when the repair is complete, especially after the patched holes are given time to weather.
This is beneficial for decorative areas, or where a larger, more visible patched hole would bother you.
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Minimal Mess During Application
The foam concrete lifting process can be mess-free due to its self-contained nature. This is ideal for spaces that require clean, nearly dust-free applications, like surgical wings of hospitals.
However, if the foam happens to leak out and get stuck on the concrete or surrounding surfaces, it can cause chemical stains that can be very difficult (if not impossible) to remove.
Cons of Foam Leveling
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Cost Compared to Other Methods
Foam leveling is usually the most expensive method of concrete leveling. Foam leveling uses synthetic materials and chemicals, which cost more than the natural alternatives.
For larger jobs, this higher material cost is a big roadblock.
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Difficult To Fill Voids Completely
Due to the nature of foam, it’s very hard to fill the crevices and space under a sunken concrete slab as it expands.
What happens is “pancaking,” which is when foam spreads out in a small area, not filling the void, and technicians add layers to the stack until the slab is lifted.
This “pancaking” effect creates weak points where the individual “pancake stacks,” or pillars, hold up an entire slab of concrete, which has a higher chance of cracking where the base is unsupported.
Read more about why voids under concrete should be filled properly.
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Less Control and Over-Lifting
When technicians stop injecting the foam leveling solution, the lift doesn’t stop – the chemical reaction that takes place after the material is in the void continues to lift.
Foam’s chemical reactions are also highly sensitive to temperature and pressure, and the pressure of the confined space under the slab can lead to inconsistent expansion.
These factors reduce control and make it easier to overdo the repair and lift the slab too far out of place. And once the slab is lifted, there’s no way to lower it back down again.
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Safety Concerns and Bad Chemical Reactions
Because of the nature of the foam’s chemical reaction, it produces a lot of heat. When large amounts are injected at one time, this heat can cause the foam to damage itself from the inside, which can lead to shrinkage.
This can also reduce the compressive strength and overall durability of the foam supporting the slab and repair.
Another concern arises if the foam is mixed incorrectly or the chemical ratio is off. In this case, there is a greater risk of the foam turning out weak, brittle, or soft.
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Environmental Concerns
While most foams are presented as eco-friendly, they are ultimately made from petroleum-based raw materials and synthetic chemicals.
Also, when the concrete needs to be removed later, the foam will likely not be recyclable like concrete alone is now. How much foam lifting materials can be recycled is still unknown, but polyurethane foams have historically had a very low recycling rate.
Note: There is ongoing research and development to improve these environmental factors related to the entire foam product industry.
Should You Lift Your Concrete With Foam?
Now that you know a little more about the advantages and disadvantages of foam-injection concrete leveling, you’re one step closer to deciding if it’s the right method for you.
However, each situation is unique, and an experienced concrete leveling professional will be able to shed light on the best route to take based on your specific circumstances.
But whichever concrete leveling method you end up going with, the goal is to return your settled concrete back to a safe and even position, and polyjacking is just one way to do that.
If you’re ready to see what concrete leveling can do for your property, click the link below to request a free onsite estimate with a member of the A-1 team near you!
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