A highly experienced crew using button bit drills and a new-design grout pump helped American Concrete Raising Inc. to raise a settled floor slab in a supermarket--without closing the store during business hours.

The building is supported on drilled pier foundations, but the floor slab rests on loose fill material. The fill was disturbed when an excavation was made for constructing a building nearby. Instead of replacing the damaged slab, the owners decided to use a void filling and slabjacking approach.

For each section of the floor, workers drilled holes in the floor, pumped grout to raise the slab, patched the holes, and replaced floor tiles during an 8-hour period. To pump grout for raising the slab, workers used a self-propelled pump with remote control.