Concrete – Rotating a concrete slab

A healthy 6" slab is probably robust enough to handle quite a bit of movement without cracking. You just need to lever it around, not lift it. (Maybe that's what you meant.)

• Clear all material away from the slab in the direction it's to be moved.
• Pothole at several locations on the "push" side of two corners about 12", tight to the slab.
• Insert a 6-foot 2x4 in each pothole, and stand it up with the narrow edge against the slab. Place a block between the lever and the slab to prevent damage to the slab edge.
• Block against the bottom of the lever.
• With helpers, pry the levers in the direction of movement.

Depending on the nature of the substrate, the slab should spin with relatively little effort. (Ideally it was poured on gravel or washed rock.) Once it's in the new position, check level. Then...

• Using a garden hose, jet under the slab at approximately 24" intervals from opposing sides, just enough to get the hose to the center. This will soften the soil and allow re-settling. Avoid jetting crosswise near the ends so you don't remove too much soil there.
• If the slab needs further leveling, jet in more frequently at the high side and flush out a bit of material.

Finally, return to the levers and give the slab a few nudges to encourage a final settling action. Let the soil alone for a few hours to a few days so it can desaturate and stabilize before applying weight or movement to it.

Warning: If you get clever and start winching on these levers, use your head. A heavy stick of lumber becomes a loaded weapon when stressed. A slipped tether or broken strap can knock out teeth or much, much worse. This much weight brings inherent risks that must be respected.