concrete repair Ogden, Utah

How Concrete Repair Contractors Find Voids Under Concrete

When faced with cracked or sunken slab, concrete repair contractors in Ogden, Utah, solve the problem by conquering the subsurface voids. These pockets of air in the soil can form as a result of moisture infiltration, erosion and a host of other factors, but in any case, the spaces must be eliminated. By doing that, filling the voids with a special cement slurry mixture, professional contractors are able to raise and stabilize the concrete.

The question is, how do concrete repair contractors find subsurface voids? Empty spaces under concrete obviously aren’t visible – otherwise, Ogden homeowners and business owners would likely address the issue before a slab sinks or develops cracks. So, what approach do professionals take to determine where the voids are located?

When it comes to concrete repair, ground penetrating radar (GPR) is the key player. Below, the Lift-Up Concrete team explains how the technology works.

Using Ground Penetrating Radar

Ground penetrating radar is an efficient, non-invasive method for identifying subsurface features. Commonly used in construction, engineering, archeology and various other scientific and commercial applications, GPR is also an extremely useful tool for concrete repair contractors. The advanced imaging technique captures detailed information regarding what’s under the slab, and it clearly shows the location of and dimension of any subsurface voids.

So, how does GPR work? Essentially, the technology is like an X-ray scanner that can penetrate concrete. The equipment itself is similar in size to a small lawn mower, and concrete repair experts can typically complete a GPR scan in less than an hour.

To do so, the equipment, which is similar in size to a small lawn mower, is slowly and carefully driven across the entire repair area. As it moves along, radio pulses are sent through the concrete and into the soil below. When a void or any other anomaly is detected, a signal is sent to the receiver. By sizing up the reflected signals, concrete repair contractors can determine exactly where the pockets of air under a slab are located.

Interpreting the GPR Scan Data

While ground penetrating radar produces highly accurate results, it takes expertise to understand GPR scan data. Not every signal indicates an air pocket – some point to underground pipes, utilities, storage tanks and other subsurface structures. And, the data comes in the form of a wavy line map, not as actual pictures of what lies underground. How, then, do concrete repair professionals pinpoint the position and proportion of the soil voids?

When GPR signals are sent through different materials, their conductive and dielectric properties create distortions. By analyzing these irregularities, experts can identify subsurface voids, along with rocks and items made of wood, metal and PVC.

Most professional concrete repair contractors, including Lift-Up Concrete, have the training and skill to conduct GPR scans and interpret the results. This knowledge is essential in this line of work, as the soil voids under a cracked or sunken slab must be filled to restore the integrity and stability of the concrete. However, for anyone without expertise, the variables at play can make GPR data quite difficult to understand.

Taking Steps to Abolish Soil Voids

After determining the precise location of the air pockets under a slab, concrete repair professionals take the necessary steps to fill them. As we’ve mentioned, eliminating the subsurface voids is the key to raising and stabilizing cracked, settled or sunken concrete. So how is this accomplished?

First, using a high-powered concrete drill, a few small holes – each about two inches in diameter – are bored through the surface of the affected slab. Next, professional contractors use a hydraulic pump to send a specialized slurry mixture into the soil voids. Once the air pockets have been filled, concrete repair experts use the resulting pressure to guide the slab into the proper position.

When the surface is level, the concrete is stable. At this point, the only task left is to caulk and seal the holes and cracks in order to prevent water infiltration. Some Ogden homeowners and business owners handle this themselves, but in many cases, professional contractors include this step in concrete repair estimates.

Does Filling Soil Voids Provide a Permanent Fix?

The cement slurry mixture that concrete repair contractors use to fill subsurface voids is incredibly strong, and most restored slabs remain stable for at least a decade. But as much as we’d love to say that the results last forever, that isn’t the case.

Many parts of Ogden, Utah, have poor soil conditions. Burrowing animals are a common problem, too, and other issues – like improper land grading, poorly placed gutter downspouts and tree root growth – can affect the integrity of concrete structures. And, of course, heavy rainfall, floods and serious plumbing leaks can drive a great deal of moisture into the soil. For all of these reasons, it’s likely that new air pockets will form in the future. Even so, a repeat concrete repair project won’t be necessary for quite some time.

Do you have a cracked or sunken concrete slab at your home or business property? If you’re in Ogden or the surrounding Utah area, the professional team at Lift-Up Concrete can provide you with an expert repair at a reasonable price. For a free, no-obligation concrete repair consultation and estimate, contact us today.