Why Does Concrete Sink?
Concrete Settlement Causes
When addressing concrete settlement, we know that soil is usually the primary cause, but we have to dig a little deeper to find out why the soil has shifted or eroded. Having that information is important to provide the right repair solution. The three main causes of concrete settlement are:
- Shrinkage and expansion of the soil
- Washed out soil
- Improperly compacted soil
Soil contracts and expands as it absorbs moisture and then dries out. During dry seasons, the soil will shrink. When the soil becomes saturated in wetter months, it expands. This cycle of shrinkage and expansion creates movement under the concrete slab, causing it to sink.
Over time, water can find its way beneath the concrete. Water from heavy rains, snowmelt, or plumbing issues can erode the dirt beneath the concrete slab, leaving gaps. The heavy concrete then settles into those empty areas, causing cracking and sinking.
Concrete needs to rest upon solid soil. During construction, the soil beneath the concrete needs to be properly compacted to give it enough support to remain stable. If the soil is too loose, it will compress as the heavy concrete rests on it, and this will cause the slab to sink and become uneven.
