Concrete in Ontario has a hard life: freeze-thaw, road salt and heavy vehicles. Not every crack means a new driveway. Here's how to read the damage.
Hairline cracks
Thin cracks, especially along the control joints, are normal. Concrete shrinks as it cures. Sealing them keeps water out so they don't widen in winter.
Wide or uneven cracks
Cracks you can fit a coin into, or where one side is higher than the other, usually mean the base has moved. If it's one or two sections, lifting and sealing may fix it. If it's spread across the slab, replacement is usually better.
Sunken sections
A section that's dropped near the garage, the house or the street is usually from base that washed out or was never compacted. If the slab is still in one piece, it can often be lifted back to level with foam or slurry. If it's broken into pieces, it's a replacement.
Flaking and scaling
When the surface pops off in flakes, it's usually freeze-thaw damage made worse by salt. Shallow scaling on an otherwise sound slab can be resurfaced. Deep spalling with exposed stone or rebar usually means replacement.
How to make concrete last
- No de-icing salt on new concrete for its first winter. Use sand for grip.
- Seal driveways and patios every two to three years.
- Shovel early, so snow isn't packed into ice by tires.
- Keep downspouts and grading sending water away from slabs, not under them.
- Avoid de-icers with ammonium nitrate or ammonium sulphate, which attack concrete.
Not sure what yours needs? Send the form at the top of this page and a local contractor can take a look and tell you honestly whether to repair or replace.