Concrete Void Filling in Illinois for Hollow & Settled Slabs
Voids beneath concrete can develop from soil settlement, erosion, poor drainage, washout, or improper backfilling. Scritchlow provides concrete void filling for driveways, sidewalks, patios, garage floors, steps, and other concrete slabs throughout Central and Northern Illinois.
A site evaluation can help identify what caused the void and determine whether void filling, slab jacking, or another repair approach is appropriate.
What Causes Voids Under Concrete?
Voids form when the soil beneath a concrete slab loses support or moves away from the underside of the concrete. This can happen gradually or after repeated water movement around the slab.
Common causes include poorly compacted soil, natural soil settlement, erosion, drainage problems, downspouts discharging near concrete, washout, and improper backfilling.
When enough support is lost, the slab may begin to settle, become uneven, or develop hollow areas beneath the concrete. Identifying the underlying cause is important because drainage or soil problems may also need to be corrected.
Common causes of voids beneath concrete:
- Poorly compacted or settling soil
- Water erosion and washout
- Poor grading or drainage
- Downspouts discharging near slabs
- Improper backfilling
- Soil movement around foundations and structures
How Concrete Void Filling Works
Concrete void filling restores support beneath slabs where soil has settled, washed away, or left empty spaces under the concrete.
During the process, material is placed beneath the slab to fill unsupported areas and improve contact between the concrete and the underlying base. Depending on the condition of the slab, void filling may be performed by itself or as part of a concrete lifting project.
Before work begins, the slab, surrounding soil, drainage conditions, and amount of settlement should be evaluated. If water movement or poor drainage contributed to the void, those conditions may also need to be addressed to reduce the chance of continued soil loss.
- Fill unsupported areas beneath concrete
- Restore support beneath settled slabs
- Suitable for driveways, sidewalks, patios, and garage floors
- May be combined with concrete lifting when needed
- Drainage and soil conditions evaluated before repair
When Is Pressure or Compaction Grouting Needed?
Standard void filling is suitable for many concrete slabs, but some projects involve deeper voids, unstable soil, or more significant settlement.
In these situations, pressure or compaction grouting may be considered to improve support within the soil beneath a slab or structure. The appropriate method depends on the depth and size of the void, soil conditions, accessibility, and the type of structure involved.
A site evaluation is necessary before recommending specialized grouting because not every settlement problem requires the same repair method.
- Larger or deeper underground voids
- Loose or unstable soil conditions
- Significant settlement
- Areas requiring deeper soil support
- Projects that are not suitable for standard slab jacking alone
Void Filling FAQs
Get answers to common questions about concrete void filling, hollow slabs, soil settlement, erosion, drainage, and when concrete lifting may also be needed.
Concerned About Voids Beneath Your Concrete?
Hollow areas, settling, erosion, or uneven slabs can be signs that support has been lost beneath the concrete. Scritchlow can evaluate the area and help determine the appropriate repair approach.