3 Methods to Repair Sunken Concrete

Uneven concrete isn’t just an eyesore—it’s a safety hazard that can lead to trips, falls, and costly damage over time. If you’re dealing with sunken or uneven concrete slabs around your home—in a sidewalk, driveway, or patio, for example—you may be wondering whether to repair or replace them. The good news? You have options. 

There are three primary methods to consider, each with its own advantages and drawbacks, but ultimately, there are effective ways to lift and stabilize your concrete without the hassle of a full replacement. The right solution depends on the condition of the slab and the underlying cause of the settlement. For this reason, it’s wise to consult with a professional concrete repair expert, who can determine the most effective approach for your needs.

Keep reading as we break down the three methods to get your concrete looking and functioning like new again.

1. Replacing or Repairing Concrete

When concrete is heavily cracked, replacing the slab might seem like the obvious solution. But there are some clear drawbacks to this approach. For example:

• Replacing the existing concrete with a fresh slab may look appealing, but it often won’t match any surrounding concrete in color or texture.
• Pouring new concrete doesn’t solve the root cause of the problem. If the original slab settled due to unstable or compacting soil, the new concrete will likely suffer the same fate. Pouring over weak or shifting ground only offers a temporary fix.
• Replacing concrete is typically the most expensive of the three options, making it a less practical solution in many cases.

2. Mud Jacking

Mud jacking is a common method used to lift sunken concrete back into place.

The process involves drilling small holes (typically 1 to 1 5/8 inches in diameter) into the slab at key locations. A thick grout mixture, made from finely crushed limestone aggregate and sometimes Portland cement, is pumped through the holes. As the slurry fills any empty spaces beneath the slab, it gradually lifts the concrete.

Some of the disadvantages of mudjacking include:

• Added weight — Although mud jacking is less invasive than full slab replacement, it does add significant weight to the area. This can be problematic if the original settlement was caused by weak or compressible soil, as the added load may cause further sinking over time.
• A messy process — The process can be a bit haphazard, and any blowouts during the injection can be difficult to clean.
• Lengthier repair time — Mud jacking takes longer to cure than polyurethane foam injection and causes more downtime before the homeowner can make use of the repaired slab.

3. Polyurethane Foam Injection

Polyurethane foam injection is another effective solution for lifting and stabilizing settled concrete slabs.

This method uses a closed-cell polymer foam, which repels water and doesn’t absorb moisture. The foam is injected through small, dime-sized (5/8 inch) holes drilled into the slab. A port is inserted into the hole, allowing the foam to be delivered beneath the slab.

As the two-part polyurethane mixture combines, it creates an expanding foam that lifts the slab by filling voids and compacting weak soils. The foam expands quickly—reaching full expansion in about 15 seconds—and cures in roughly 15 minutes. The slab is often ready for use within 30 minutes.

In addition to being ready to walk on within minutes of repair, polyurethane foam has a number of other advantages, including that it is:

• Lightweight, which reduces the risk of further settlement 
• Resistant to erosion and maintains its shape and volume over time, making it a durable, long-term solution
• Made with recycled materials, so it’s an eco-friendly option
• Less expensive than full concrete replacement, making the repair easier on your wallet

Choose the Right Concrete Repair Solution

If you’re unsure which method is best for your sunken concrete issue, reach out to the experts at Ox Foundation Solutions. Our team will assess your situation and recommend the most effective and lasting solution. Contact us today and request a free estimate. We serve homeowners in Birmingham, Pelham, Montgomery, Huntsville, Mobile, and other areas throughout Alabama and are here to help keep your concrete Ox Strong!