What Causes My Concrete to Sink and Settle?

Sinking and settling concrete slabs is not entirely uncommon, especially if you live in Richmond and Petersburg, VA. If you leave your concrete slabs without repair for long enough, these sunken or settled slabs can even crack or break. This is not only disruptive to your landscape aesthetics and unsightly to look at, but sunken or broken concrete can also be hazardous, as it can cause you to trip and possibly hurt yourself. There are several reasons why concrete may sink or settle: 

• Soil erosion
• Soil shrinkage, compaction, and settlement

Soil erosion, or soil washout, is a very common phenomenon in sand-based soils because sandy soils are very fine in texture and have tiny soil particles. When exposed to water or wind, sandy soils can become easily washed away, or eroded. Constant rainfall and seasonal melted snow is typical of Richmond and Petersburg, VA, so soil erosion is very common. When soil becomes eroded underneath concrete slabs, this can leave gaps. Less soil means less support for these heavy concrete slabs, resulting in sunken or settled concrete.

Virginia also has part clay-based soil mixed with the sand-based particles. Clay soil particles are infamously difficult to manage because they swell to double or triple their size when they absorb water but shrink back down to their original size when it dries out. Repeated cycles of shrinking and swelling during rainy and drier seasons of the year can cause surrounding soil to shift, which can weaken the integrity of the soil. Weakened soil can easily become compressed under the heavy weight of concrete and settle to lower levels. Concrete beds have less support when this happens, thus, resulting in sunken or broken slabs.