What causes concrete to spall in New Brunswick driveways and how is it repaired?

Concrete spalling in New Brunswick driveways is almost always caused by freeze-thaw damage combined with de-icing salt penetration — and NB's climate makes this one of the most common and destructive concrete problems in the province.

Spalling is the flaking, pitting, and scaling of the concrete surface where the top layer separates and breaks away in chips or sheets. It looks like the concrete is peeling from the inside out — because it essentially is. Water penetrates the microscopic pores in the concrete surface, freezes, and expands by roughly 9%. With 150+ freeze-thaw cycles per year in New Brunswick, that expansion-contraction stress repeats relentlessly through every NB winter. The surface layer eventually delaminates and breaks away.

De-icing salt dramatically accelerates this process. Sodium chloride (regular road salt) lowers the freezing point of water, which sounds helpful but actually creates more freeze-thaw cycles at the concrete surface than ambient temperatures alone would produce. Salt-laden slush splashes onto NB driveways from November through April, and the salt solution wicks into the concrete surface. When it refreezes, the damage compounds with every cycle. New concrete is especially vulnerable — concrete less than one year old has not fully cured and its surface is particularly susceptible to salt damage.

The other major cause is poor original construction. Concrete placed without air entrainment will spall in NB conditions within 3-7 years, guaranteed. Air-entrained concrete contains billions of microscopic air bubbles (4-7% air content) that give freezing water room to expand without fracturing the concrete matrix. Any exterior concrete poured in New Brunswick without air entrainment is living on borrowed time. Finishing mistakes also contribute — overworking the surface, adding water to the mix at the jobsite, or finishing while bleed water is still present all weaken the surface layer and make it prone to scaling.

Repairing Spalled Concrete

The right repair approach depends on the depth and extent of the damage.

Surface scaling (less than 1/4 inch deep, less than 25% of the surface) can be addressed with a concrete resurfacer product like Quikrete Concrete Resurfacer or a polymer-modified overlay. The surface must be thoroughly cleaned, all loose material removed with a wire brush or pressure washer, and the area profiled so the new material bonds properly. These products are available at NB building supply stores for $30-$60 per bag. This is a manageable DIY repair for a homeowner who is comfortable following product instructions carefully.

Moderate to severe spalling (deeper than 1/4 inch, large areas, or active pitting) requires more involved repair. A contractor will grind or scarify the surface to remove all deteriorated material, apply a bonding agent, and install a polymer-modified overlay or micro-topping at the appropriate thickness. Expect to pay $3-$6 per square foot for professional resurfacing on a typical NB driveway.

Widespread spalling affecting the full driveway is often a sign that the original concrete was poorly specified or placed. At this point, resurfacing is a temporary measure — the underlying concrete will continue to deteriorate and the overlay will eventually fail along with it. Full driveway replacement at $8-$15 per square foot is the honest long-term answer, and the new concrete must be specified correctly: air-entrained mix at 32 MPa minimum, 5-6 inches thick, with proper reinforcement and control joints.

Preventing Future Spalling

After any repair or new pour, apply a penetrating silane/siloxane sealer — this is not optional in NB. A quality penetrating sealer ($40-$80 per gallon) repels water and salt solution from entering the concrete surface. Reapply every 2-3 years. Switch from road salt to sand for traction, or use calcium magnesium acetate if you need a chemical de-icer. And never apply any de-icer to concrete less than one year old.

Need help finding a concrete contractor for driveway repair or replacement? New Brunswick Concrete can match you with local professionals for free — browse the directory at newbrunswickconstructionnetwork.com/directory?trade=concrete.