What Causes Concrete to Settle?

Compaction fails: The base of a concrete slab must be properly compacted to ensure the strength and durability of the finished product. It is important to know that if the base is not properly compacted, there are risks of settlement, resulting in cracks in the slab.
Soil: Concrete will sink when placed atop heavy clay soils, which typically enlarge when wet and shrink when dry. As a result, it's important to note the depth of these soils before pouring concrete. Soil composition is typically determined by testing the depth with a core sample or auger drilling.
Trees: Trees can be a major cause of pavement settlement when they draw in large quantities of water. The roots in the tree push down beneath the tree's surface to take in more water and, in turn, dry out the soil around it, leading to a decrease in the level of moisture, which may cause nearby concrete to become settled.
Climate: Foundation problems can be caused by frost heaves. When frost expands and contracts, it can crack pavements. When the ground thaws, it does not always shrink back to its original size.
Abrasion: Poorly placed downspouts and sewer lines can lead to water seeping into your foundation, damaging or weakening it. Water abrasion can present itself in the form of cracks, bulges, or uneven surfaces.
Traffic or Machinery: If your building is in an industrial area, the constant vibrations from trucks and trains causes the slabs to shift over time. These consistent vibrations and traffic result in major damage to the building. Slabs can shift up to 2 inches or more vertically or 3 horizontally.