How do I repair a cracked concrete driveway in NB?

The right repair method depends on the size, depth, and cause of the crack — and in New Brunswick's climate, a proper repair done now prevents a minor crack from becoming a major failure by spring thaw.

For hairline cracks and surface cracks under 1/4 inch wide, a DIY repair is reasonable. Clean the crack thoroughly with a wire brush and compressed air or a shop vacuum to remove all debris, loose concrete, and dust. Apply a concrete crack filler — either a polyurethane or epoxy crack filler from your local building supply store — following the manufacturer's directions. These flexible sealants bond well, resist freeze-thaw movement, and stop water infiltration. Avoid standard latex caulk, which breaks down quickly under NB freeze-thaw conditions.

For cracks wider than 1/4 inch or cracks showing vertical displacement (one side higher than the other), the repair is more involved. You may need to widen the crack into a V-shape using an angle grinder or cold chisel to create a better bonding surface, then pack with a vinyl concrete patch compound or hydraulic cement. Cracks with displacement indicate underlying movement — soil settlement, tree root intrusion, or frost heave — and patching the surface without addressing the cause means the crack will return.

NB's freeze-thaw cycle is the underlying enemy here. Water enters a crack, freezes, expands by 9%, and widens the crack with every cycle. New Brunswick experiences over 150 freeze-thaw cycles annually — more than almost anywhere else in Canada. Even a hairline crack left unrepaired over a Moncton or Fredericton winter will typically be 2-3 times wider by April. The best time to repair cracks is late spring (May-June) after the ground has fully thawed and stabilized, or early fall (September-October) before temperatures drop below 5 degrees Celsius at night.

Before you repair, seal. Once your cracks are filled and cured, apply a penetrating silane-siloxane sealer across the entire driveway surface. This is the single most effective step you can take to extend the life of NB driveway concrete — it repels the salt-laden water that causes 80% of concrete deterioration in our climate.

If your driveway has extensive cracking, surface scaling over a large area, or cracks that keep returning in the same location, patching is a losing battle. At that point, replacement with a properly specified 5-6 inch air-entrained concrete slab is the better long-term investment. New Brunswick Concrete can match you with local driveway contractors for a free assessment and quote — use the matching service to compare a few opinions before committing either way.