Yes, you can mudjack cracked concrete, but the cracks will need to be repaired once the concrete has been leveled. If the concrete is severely cracked in multiple places, replacement may be a better option, but for less severe cracking, mudjacking is a good solution as long as cracks are correctly caulked and sealed.

Yes, expanding foam (also known as polyurethane foam) can lift concrete. This approach, called polyjacking, involves injecting the foam rather than concrete slurry to fill voids and raise the concrete slab back into place. It’s often faster and requires smaller drill holes than traditional mudjacking, though it may come at a higher cost. Some contractors also prefer polyjacking over mudjacking for more damaged and delicate slabs.

Polyjacking and mudjacking can both be effective solutions for sinking concrete, but they have key differences. Polyjacking, which uses expanding polyurethane foam, is often considered a better option because the foam is significantly lighter than the cementitious material used for mudjacking. This reduced weight puts less pressure on the underlying soil and lowers the risk of future sinking. Polyjacking is suitable for any sinking concrete slab, while mudjacking is typically only recommended for non-structural concrete, such as sidewalks, patios, pool decks, and driveways. The primary drawback of polyjacking is its cost, which can be up to four times higher than mudjacking—as much as $25 per square foot compared to a maximum of about $6 per square foot for mudjacking.

The polyurethane used for polyjacking will expand and cure in 15 to 30 minutes. After that point, your slab will be safe to walk on and even drive on in the case of a sidewalk or concrete driveway. Double-check with your concrete lifting specialist to confirm a curing timeline, as products can differ.