Concrete is often poured over recently backfilled soil around a home after construction. This loose soil settles over time, creating a void under the concrete. Another common cause of concrete slab movement is erosion of the soil underneath the slab. As water runs down through the cracks and joints in the concrete, it washes the soil out as it passes through. This creates voids in your concrete, causing it to shift and settle, producing a cracked and uneven surface, as well as dangerous tripping hazards.