What Are the Causes of Uneven Concrete and Driveways?

Uneven concrete is all about the soil that’s used as a foundation. When it gives way or shrinks and loses its topsoil volume, a void remains and there’s nothing supporting the concrete. This is something that cannot be prevented, and very little can be done in the face of earthquakes and floods, but certain measures can be taken in order to prevent soil erosion and shrinkage.  

• The Kind of Soil 

The type of soil used as the foundation for the driveway impacts how severe and how quickly the settling is. Soils with big, grainy particles tend to wash away because water is able to pass through easily. It’s the kind of soil that doesn’t compact well, so it’s loose and shifty. It’s vulnerable to floods, snow, rain, and earthquakes. 

Expansive soils (often clay soils) compact well, so they are denser and make for a much better foundation. However, because of the clay content in the soil, expansion occurs at a higher rate. The more the soil is able to expand, the more it’s able to shrink. Despite its swell-shrink capacity, contractors still use clay soils because it compacts easily. This makes it easier to manipulate and saves time when laying down the foundation. 

• Soil Shrinkage  

Soil shrinkage occurs when the moisture in soil dries out. As the moisture leaves the soil, the individual particles come together since there is nothing between them anymore. The soil becomes denser, but due to shrinkage, it loses surface volume. 

Once the soil loses surface volume, there is nothing supporting the concrete. With the added weight of cars, snow, and people walking on the driveway, the concrete gives way and settles on the soil. Soil shrinkage is a naturally occurring process that can’t be controlled or predicted, but placing a canopy over the driveway will limit the concrete’s exposure to the elements and mitigate the damage done by soil shrinkage.