Driveways, walkways and sidewalks are exposed to a lot of wear and tear. When the soil supporting it becomes weak or a void is formed, concrete slabs can crack and sink. There are many things that can create a void beneath a concrete slab, such as erosion from rainwater or gutter runoff, or a tree root that has rotted over time. Clogged gutters, downspouts that are not installed correctly, and poor yard drainage can make erosion worse. Dirt fill underneath the slab that has not been well compacted can also create voids beneath concrete.