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Expansive Soil and its Impact on Concrete

The underlying, expansive soil is responsible for the majority of damage to your property’s concrete structures. Learn more about this issue and how Peak Structural can help.

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Concrete structures like your driveway and sidewalk can sustain damage for many reasons, but it all boils down to the underlying soil. Expansive soils prevalent throughout Colorado are volatile and contribute to problems with concrete cracking and sinking. Read on to learn more about what’s happening on your property.

How Do Expansive Soils Work?

While many soil types exist across the country and the globe, there are three basic ingredients in soil – sand, silt, and clay. DenverColorado Springs, Grand Junction,  and other areas in Colorado are rich in clay soil, particularly bentonite clay. Bentonite is an additive that can be mixed with sandy soil for more strength and durability, but it naturally occurs in Colorado and is problematic primarily because of the area’s weather.

Drying and Shrinking During Drought

One way soil can become unstable is by drying and shrinking. This is a common occurrence during Colorado’s frequent periods of drought. Without consistent moisture levels, clay soil dries up, shrinks, and leaves structures like concrete slabs without proper support. As the soil shrinks and settles, the above concrete follows suit. 

Saturation and Expansion During Heavy Rain

Colorado receives less rainfall than the national average, but any heavy rain or snowmelt can take its toll on soil. Clay soils like bentonite clay absorb a lot of water when saturated and significantly expand. As they expand, they exert a great amount of force, known as hydrostatic pressure, on anything nearby including concrete slabs. This continued force can lead to various concrete damage.

The Risks of Expansive Soils

The combination of Colorado’s weather and expansive bentonite clay soil creates a recipe for disaster for concrete structures. Here are some ways expansive soil can impact your concrete slabs.

Cracked Concrete

As soil expands and hydrostatic pressure is exerted, this force can become too much for the concrete to bear. This will be visible in cracks and fissures throughout the concrete slabs. These cracks can appear in the middle of the slabs or along the edges and corners. Shrink-swell and freeze-thaw cycles throughout the year will only create more cracks and worsen existing ones.

Sinking and Uneven Concrete Slabs

When expansive soil shrinks during periods of drought, it leaves voids under concrete that the slabs can easily settle into. When concrete slabs sink and settle into the ground, the surface is no longer even. This is most visible and dangerous in sidewalks and pool decks.

Safety, Aesthetics, and Home Value

This is not an exhaustive list of concrete problem signs, but issues like cracking concrete and sinking, uneven slabs impact your home in other ways. Concrete cracks and slabs that are not even are tripping hazards that affect the safety of your family and guests. Cracking and uneven concrete slabs also make your property look unkempt. These factors of safety and appearance greatly affect your home’s resale value, as well.


There are thousands of different soils around the world, but their basic makeup consists of sand, silt, clay, or a combination of any or all of these. Sand tends to quickly drain water and silt has intermediate drainage properties. Clay soil holds onto water better than sand or silt, which is why it is known as an expansive soil. Expansive clay soil can be found throughout the country, and it is prevalent in areas of Colorado including Denver, Colorado Springs, and Grand Junction.

Expansive soil, particularly bentonite clay soil, can be found throughout Colorado. It’s not feasible to replace all the soil under and around your home or your property’s concrete, but there is something professionals can do to stabilize problematic concrete and the soil beneath it. PolyRenewal™ polyurethane injections work by being pumped under sinking concrete slabs. This lightweight foam expands to fill voids between the soil and concrete slabs, lifting the concrete along the way. Not only will the concrete be stabilized, but so will the underlying soil as well.

How much soil expands is often dependent on the weather. If it is dry, the soil will begin to shrink and settle, bringing part of all of your concrete slabs or foundation down with it. If it is particularly wet, the saturated soil can greatly expand press up against your concrete and foundation with a great amount of force. In both situations, concrete slabs and your foundation could sustain minor cracking and shifting at first. But as these shrink-swell cycles continue, significant damage can result in cracking and uneven concrete as well as bowing walls and a settling foundation. All of which can be safety hazards and result in extensive repairs.

Address Expansive Soil and Concrete Problems with Help from Peak Structural

You may not be able to see expansive soil at work at first glance, but you’ll know it’s happening when your concrete slabs begin to crack, sink, and become uneven. If you notice these issues in the concrete around your property, don’t hesitate to reach out to the expert team at Peak Structural for a FREE inspection today. These problems will only get worse over time, and they need to be taken care of right away to ensure your health and safety. 

Our professional inspectors and installers have years of experience with diagnosing and repairing concrete problems like expansive soil. We are proud to serve homeowners like you in communities throughout Colorado including DenverColorado Springs, Grand Junction, and the Pikes Peak region. We look forward to helping you create a safer living environment. Call today!

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