There are several possible reasons for concrete slabs to slump, sink, or settle below the desired finish grade. In Many instances time will allow the finish grade of slabs to change (settle, sink, or slump) due to failure of backfill and lack of soil compaction during construction, or erosion from poor drainage.
Over time, moisture from poor or inadequate drainage can cause the fill under the slab to settle and compress under the weight of the concrete slab, thus allowing the unsupported concrete to fail because of inadequate support from soil beneath the slab. Some soils such as clay, will expand and contract under the influence of moisture and weight, and can be the cause of slab failures.
In most cases placing a bed of gravel and then properly compacting it will prevent slap failures. The exception can occur during improper drainage events. Properly engineered gutter and downspout placement can alleviate water drainage issues which in turn can aggravate concrete slabs. During the life of the slab drainage plays a critical role in concrete slab stability.
Of course proper concrete steel reinforcements such as Re-Wire and Re-bar are helpful in preventing fractures and settling.
Reputable concrete contractors such as Poppenga Concrete Construction, LLC will recommend proper drainage and fill methods to use in your next project. Call Dave at 417-379-5441 or request a Free Estimate here.