You’ve probably seen sunken concrete slabs on sidewalks or pavements around your home. There are a variety of reasons for why concrete slabs sink and settle, but the primary cause for sunken concrete slabs is changes in the soils beneath the cement. Whether the soil foundation is poorly compacted, undergoes drying and shrinking, or becomes washed out by the elements, concrete slabs begin to settle in a sunken fashion because of the void that is left below the slab. If the concrete is not strong enough to withstand the void, the cement slabs will eventually crack, break, and settle into a new formation, becoming uneven with all of the other slabs.
Concrete Settlement Can Cause Serious Damage
Cement that settles along the sidewalk or on a driveway may not pose a structural threat to the buildings and homes around it. It can however present a physical danger of tripping, falling, and badly injuring the body. Concrete settlement can cause serious damage when it occurs in places that are directly related to the foundation and structure of a building. Noticing uneven cement, cracking or shifting in the pavement of your porch, basement, or concrete around the exterior of your home could be an indication of shifting soils. Soil erosion, washout, and drying can be a major problem for the stability of any home or structure.
Drying and Shrinking
When soils beneath a concrete floor slab become dry and shrink, the foundation takes on a new shape and form. Moisture in the soil causes it to expand and become more full than when it is dry. Dry soil will shrink and create unwanted space below the concrete slabs, causing them to settle on the newly formed foundation. If the partition walls and structural foundation of your home begin to settle with the sinking concrete slabs, cracking in the drywall will occur.
It is a common practice to install plumbing lines underneath concrete slabs. If those plumb lines start to leak, it can cause the soil foundation to wash away, leading to settlement and cracking. Washout is not always preventable, and it often goes without detection until the concrete slabs above the plumb lines become cracked.
Concrete settlement is fairly common in homes and buildings across the United States. Understanding what causes concrete slabs to settle is important for knowing how to repair and fix concrete that becomes broken and cracked.