How Do You Fill Voids Under Concrete Slabs?

Filling Voids Under Concrete Driveways, Sidewalks and More

how to fill voids under concrete slabs

In the past, techniques to fill voids that may have been used included mudjacking (or slab jacking) with a cement-based product. A more modern method of fixing voids under concrete slabs is using polyurethane foam that expands to fill the void. It may also be used to level the concrete in cases where it has been sunk due to the void.

What are the benefits of polyurethane foam?

There are several benefits of using polyurethane foam to fill voids under concrete. Here are just a few of the main reasons we recommend polyurethane foam for void filling:

  1. It is stable and long-lasting.
  2. When you use a uretnae-based grout it “cures” quickly so you can utilize that space almost immediately after the application.
  3. It can be used to stabilize soils. Whereas straight polyurethane (that used to solely raise concrete) will only fill voids.
  4. The process is minimally evasive. A small diameter hole is drilled into the concrete and the grout is pumped through that hole.
  5. Our grouts are extremely versatile! You can reach voids that would be impossible to get to with the straight polyurethane lifting foams. Our team controls the mix of the grout. This allows us to control the set/expansion time of the foam after it is injected into in the void. Imagine the void is long, narrow, and shallow. We can delay the time of expansion so the grout will travel into and throughout that void before it expands!

Sinkholes Common in Alabama

Example of a sinkhole.

A common type of void in Alabama is a sinkhole. Sinkholes can be caused by natural causes. Much of the rock in our state contains limestone which can break down when it rains. Rain is naturally acidic and can breakdown limestone in the ground causing voids. Man-made causes exist as well due to construction, drilling, and other events. To learn if sinkholes are a problem where you live click here.

Our team can help find and fix voids in numerous places beneath the concrete. We work on both commercial and residential concrete problems. To learn more about void filling and the causes of voids, or to get an estimate on void filling for your property, contact us today.