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Polyurethane Foam vs. Stone Slurry Grout Concrete Leveling

May 21st, 2024 | 4 min. read

By Sarah Etler

See how foam concrete leveling and stone slurry grout concrete leveling stack up against each other.

If you’re struggling with trip hazards and bad-looking settled concrete around your home or business, concrete leveling just might be the solution you need.

But how should you choose which of the three concrete leveling methods is right for your repair? 

In this article, we’ll give you a side-by-side look at two of these methods, polyjacking and stone slurry grout leveling, so you have a better idea of when each may be a better solution.

Want to see how all concrete leveling methods stack up against each other? Check out this resource to see them all compared.

What Is Polyjacking?

Polyjacking is a newer concrete leveling process that involves injecting expanding polyurethane foam beneath the sunken concrete slab through strategically drilled holes. It’s also called “foam leveling” and “foam injection leveling”.

When the foam enters the voids below the slab, it expands and puts enough pressure on the slab to lift it back up to a level position. Then, the foam hardens under the slab, usually within an hour, and keeps it in the level position.

Polyjacking Strengths

  • Easy To Transport  

In some cases, portable units enable technicians to level concrete in inaccessible areas that can’t be reached with the stone slurry grout hoses (200-300 feet from the leveling truck).

Note: Portable foam leveling units are not always used. Typical foam trailer/truck units (non-portable) are only able to go 200-250 feet depending on their equipment setup.

  • Drill Hole Size 

Polyjacking requires the smallest drill holes (typically ⅝”, but some systems allow for as small as ¼”) compared to the other concrete leveling methods, making them less noticeable and ideal for decorative surfaces.

  • Minimal Mess During Application

The foam concrete lifting system is self-contained, so it can be mess-free (as long as there are no accidental leaks). This is ideal for places like surgical wings of hospitals where the dust created by stone slurry grout leveling would be an issue.

  • Quick Cure Time

Polyjacking foam typically cures and can be ready for normal use within one hour. Stone slurry grout leveling repairs can be walked on immediately but are not recommended for normal use for 24 hours.

Polyjacking Weaknesses

  • Higher Cost

The materials used in polyjacking are more expensive, resulting in higher repair costs compared to the other concrete leveling methods.

  • Less Control 

The expansion of foam during polyjacking offers less control over the exact extent and direction of the lift, which may result in over-lifting or other unexpected repair outcomes.

  • Staining

Care must be taken during the polyjacking process to keep the foam off the surface of the concrete, as it can cause stains that are difficult (if not impossible) to remove.

  • Uncertain Void Fill

Due to the nature of the expanding foam, there is a possibility that the voids under the settled concrete will not be filled completely, potentially leading to a weaker repair.

  • Potential Safety Hazards

A lot of heat is produced during the chemical reaction that causes the foam to expand, and this can lead to shrinkage and a weaker repair if a lot is injected at once.

Improper chemical ratios can also cause the foam to turn out weak and brittle.

  • Environmental Concerns

Polyurethane foam is made from petroleum-based raw materials and synthetic chemicals, and likely won’t be recyclable when/if the concrete needs to be replaced.

3 Concrete Leveling Methods

Compare Leveling Types Side by Side

All three concrete leveling methods come with their own unique pros and cons. Find out which one is right for your settled concrete with a side-by-side comparison.

Learn More

What Is Stone Slurry Grout Concrete Leveling?

Stone slurry grout leveling is a concrete leveling process that involves pumping a mixture of crushed limestone, water, and sometimes Portland cement under the settled slabs.

As the mixture is pumped below the surface, it spreads out to fill voids and raise the settled slabs back to a level position. 

This concrete leveling method is often confused with mudjacking, but they are actually distinct processes.

Stone Slurry Grout Leveling Strengths

  • Strength 

Stone slurry grout leveling is stronger than both foam leveling and mudjacking due to its naturally higher compressive strengths with and without added Portland cement. 

Because it can be mixed to varying consistencies to better fill voids under the slab, it creates a solid, stronger base for the slab.

  • Control 

The stone slurry grout pumping process allows technicians to vary the material thickness depending on the needs of the repair, resulting in precise control over the lift. 

This control also helps fill voids beneath the slabs entirely, creating a solid base for the concrete.

  • Eco-Friendly 

The pumping compound used in stone slurry grout leveling is made with all-natural and environmentally friendly ingredients.

  • Locally Sourced Materials

Stone slurry grout leveling utilizes locally sourced limestone, supporting local industries and reducing transportation costs.

Stone Slurry Grout Leveling Weaknesses

  • Drill Hole Size

The drill holes for stone slurry grout leveling are larger compared to foam leveling, measuring 1" in diameter.

  • Limited Reach 

The stone slurry grout leveling job site must be within 200 to 300 feet of the truck and hoses as there are no mobile carts like with some foam leveling units.

When to Choose Polyjacking

  • Decorative Surfaces

Polyjacking is ideal for decorative surfaces, like stamped concrete, due to the smaller, less noticeable drill holes.

  • Smaller Areas

Foam leveling is also better suited for smaller areas or locations that need fewer or smaller voids filled, due to the higher material costs.

  • Non-Weight-Bearing Areas

    While it is possible to get customized, application-specific foam compositions (e.g. extra strong foam for use on highways), polyjacking typically does not provide the highest strength to support heavy loads, making it better suited for non-weight-bearing areas, like sidewalks, patios, etc. 

When to Choose Stone Slurry Grout Leveling

  • Versatile Applications

Stone slurry grout leveling is great for both interior and exterior concrete slabs, making it an option for virtually any application.

  • Larger Areas

Due to its lower material cost compared to polyjacking, stone slurry grout leveling is a good choice for larger-scale projects or when large voids need to be filled under the settled slabs.

  • Weight-Bearing Areas

If strength is a priority, such as in weight-bearing areas, stone slurry grout leveling is the better alternative to polyjacking.

  • Situations Requiring Precision and Control

Also, in situations where control and precision are important, like around pools or A/C unit pads, it’s better to go with stone slurry grout leveling.

Which Repair Method Is Right for You?

Both polyjacking and stone slurry grout concrete leveling offer a convenient and cost-effective solution when compared to full concrete replacement.

Still, it’s important to weigh the strengths and weaknesses of each option to figure out which method will be best for your specific project requirements.

Getting estimates from multiple concrete leveling companies will also help you decide the best course of action, as they will be more familiar with situations where one method is better than another.

A-1 Concrete Leveling offers stone slurry grout leveling in all nationwide locations, and foam leveling in some. Find your nearest location to request a free onsite cost estimate with an A-1 expert! 

3 Concrete Leveling Methods

Compare Leveling Types Side by Side

All three concrete leveling methods come with their own unique pros and cons. Find out which one is right for your settled concrete with a side-by-side comparison.

Learn More

Sarah Etler

Sarah Etler joined A-1 Concrete Leveling after receiving her Bachelor of Arts degree in English from Northern Kentucky University. As A-1's Content Marketing Manager, she works closely with industry experts to produce content that will best answer questions related to concrete repair and maintenance practices. Sarah loves living a life full of discovery and is excited every day to see what new things she can learn and share with those around her.