Concrete repair and resurfacing

Common repairs

• Crack repair. Routing and filling cracks with flexible sealant to keep water out before it freezes and widens them.
• Slab lifting. Raising sunken sections of driveway, walkway or patio by injecting polyurethane foam or a cement slurry underneath, often called mudjacking.
• Resurfacing. A thin bonded overlay on concrete that's sound but scaled or spalled on top.
• Step repair. Rebuilding crumbling edges and treads, or replacing settled precast steps.
• Sealing. A penetrating sealer that keeps water and salt out of the surface.

Repair or replace?

Repair makes sense when the slab is mostly sound: a few cracks, a sunken section or surface scaling. Replacement is usually better when the slab is broken into many pieces, has heaved unevenly, or the base underneath has washed out. Our guide to cracks and repairs explains how to tell.

Why concrete flakes in Ontario

Surface flaking, called scaling or spalling, is usually from water getting into the top of the slab, freezing and popping the surface off. Salt makes it much worse. Concrete that wasn't air-entrained, was finished while too wet, or was salted in its first winter is most at risk. Sealing every couple of years and using sand instead of salt on newer concrete both help.