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Expansive Soils

Expansive soils absorb tons of water from rain and other sources like drainpipes. When the soil becomes too saturated, it expands and pushes up on concrete which causes it to crack.

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South Carolina and Georgia contain copious amounts of clay-based soil and they also experience an above-average amount of rainfall. When you mix these two factors together, it can cause concrete problems as the clay fills with water and expands. All of this expansion causes uneven concrete and cracking in driveways or sidewalks. Thankfully, Mount Valley has concrete lifting solutions to lift and stabilize any damaged concrete. Here’s everything you need to know about expansive soils.  

How do Expansive Soils Work? 

In many places, loamy or sandy soil is the norm. These soils are often loose in structure, which allows water to pass through them easily. During a storm, these soils will get wet, but they won’t absorb water to the point that they grow in size. As you probably guessed, expansive soils do the exact opposite. In fact, most expansive soils tend to be clay-based. Clay soils are packed together tightly, so it takes much longer for water to drain from them. Due to their tight compaction, water may be absorbed quicker than it can drain which leads to expansion. Because of this, residents of Charleston, Columbia, Greenville, and Savannah might experience the negative effects of expansive soils during heavy rainfall.  

Not to mention, once expansive soils do finally drain, they shrink in size and become brittle, which causes the heavy concrete on top to crush through the weakened structure. This process will likely cause even more problems for the already damaged concrete. Over time, the process will repeat itself and continue to devastate your concrete.  

Risks That Come with Expansive Soils 

Expansive soils can lead to all kinds of concrete problems, including cracked concrete, flaking, and pitting concrete, and an uneven driveway and sidewalk. Concrete problems are serious, as they can lead to injuries and may indicate foundation issues in the future. 

Cracked, Sunken Sidewalk

Cracked Concrete

As you know, expansive soils will grow in size until they are pushing on the concrete above them. Concrete is a stiff material that is unable to bend and adapt under this type of pressure, so the only thing left for it to do is crack. Later on, as the expansive soil dries and sinks in size, the cracked concrete will undergo more pressure as a gap opens up between the concrete and soil. The cracked concrete will sink into the ground and crumble even further. No matter which step in the process your expansive soil is at, it never benefits concrete structures.  

Flaking, Pitting, and Staining

Since expansive soils cause concrete to crack, it also puts your concrete at risk for flaking, pitting, and staining. Each of these negative symptoms indicates that your concrete is in poor condition. Pitting refers to the deteriorating surface and structural integrity of concrete. You may notice clusters of small holes forming across sections of your driveway or sidewalk. Concrete that has been cracked by expansive soils is more likely to experience pitting. Concrete flaking is similar to pitting, and also indicates a structural issue with your concrete. However, flaking is most often brought on by moisture. The same rainfall that causes soil to expand can also cause flaking to arise in your concrete structures.  

Staining is exactly what it sounds like, the discoloration of concrete. Usually, this is also brought on by moisture like rainfall. Expanding soils cause the concrete to crack and open up even more areas of your concrete for moisture to leak into. This might cause efflorescence, mold, or other unattractive colors to appear on your concrete. Expansive soils have the potential to make all of these processes even worse.  

cracked and settling driveway concrete

Uneven Driveway and Sidewalk

Expansive will inevitably affect your driveway and the sidewalk just outside your home. Again, as the soil grows in size (and then eventually shrinks) driveways and sidewalks will crack and become uneven. This can lead to tripping on sidewalks or damage to vehicles as they enter and exit your driveway. Plus, pests might make the newly cracked concrete a temporary residence. Wasps and snakes love to slip into these small openings, raising the risk of injury to anyone passing by. Furthermore, an uneven driveway and sidewalk might also lower the value and curb appeal of your home. All of these cost you money in the long run, all thanks to expansive soils.  


Clay soil fits into the category of ”expansive soils” because of the minerals and soil particles found within it. These particles respond to water differently than sand or loam soils, both of which are loose soils. On properties with clay soil, the soil molecules are packed tightly together and often contain smectite clay particles. Smectite clay is what causes the expansion process to occur when it is exposed to water.  

You can with professional help. Expansive soils are a naturally occurring phenomenon, and you can’t easily replace the soil below your home or driveway. However, solutions exist to assist with expansive soil problems. Mount Valley uses PolyRenewal™, a polyurethane injection system that removes soil from the equation al together and keeps your concrete protected from soil issues permanently.  

In South Carolina and Georgia, they are. Much of the soil in these states is clay-based. However, construction companies often bring in soil from separate location in order to make the land better for building. Some homeowners may be lucky and have more porous soil in their yard. However, residents of South Carolina and Georgia should always be aware that expansive soils are a likely occurrence for them.  

Call Us for a Free Inspection! 

Being locals of the area, our team understands that many homeowners in Charleston, Columbia, Greenville, and Savannah are likely to experience expansive soils at some point. Thankfully, our team has the knowledge, experience, and solutions to protect your concrete structures. When you set up an appointment with us, one of our specialists can come to your home for a free inspection and determine the best course of action based on your unique problem. Don’t let expansive soils cause your concrete to suffer any longer, contact us today to learn more about our concrete lifting process! 

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