What is the best concrete crack filler for NB winter conditions?

For New Brunswick's freeze-thaw conditions, the best concrete crack fillers are flexible polyurethane sealants for surface and control joint cracks, polyurethane foam injection for leaking foundation cracks, and epoxy injection for structural cracks that need rigid bonding strength. Rigid, brittle fillers like standard hydraulic cement or unsanded grout are poor long-term choices for exterior NB concrete because they cannot flex with the 150+ annual freeze-thaw cycles the concrete experiences.

The critical rule for choosing a crack filler in NB is this: the filler must be able to move with the concrete. Every winter, exterior concrete expands and contracts with temperature changes. Cracks also open and close slightly with frost cycles. A brittle filler that bonds to both crack edges but cannot flex will eventually pop out or cause the crack to propagate around it. A flexible filler stays bonded through decades of NB winters.

For exterior cracks in driveways, walkways, patios, and steps in Moncton, Fredericton, Saint John, and across NB, the best readily available options are:

Polyurethane concrete caulk (Sikaflex, Vulkem, NP1) — the go-to filler for control joints and surface cracks up to 1/2 inch wide. It cures to a tough, flexible rubber-like consistency that bonds to concrete and survives repeated freeze-thaw cycling. Available at most NB building supply stores for $8-$20 per tube. Apply when temperatures are above 5°C (ideally 10°C or above) and the crack is dry or only slightly damp. For cracks wider than 1/4 inch, use a foam backer rod to fill the depth of the crack before applying the sealant on top.

Self-levelling polyurethane joint sealant — the same chemistry in a pour-grade formula that flows into horizontal cracks and self-levels to a smooth surface. Excellent for driveway control joints and cracks in horizontal flatwork. Brands like Sikaflex-1a Self Leveling are widely used in NB.

Epoxy crack injection — for structural cracks in foundations, garage floors, or load-bearing slabs where you need the crack to regain structural strength. Epoxy creates a bond stronger than the surrounding concrete. Not suitable for cracks that are still moving or for exterior flatwork where flexibility is needed. Professional application recommended — properly executed epoxy injection costs $500-$1,000 per crack for foundation applications.

What not to use in NB winter conditions: Standard vinyl concrete patching compounds, hydraulic cement applied alone, or rigid cementitious fillers on exterior flatwork. These products are too brittle to survive NB's freeze-thaw cycles and will crack, pop out, or cause the surrounding concrete to spall within 2-5 years.

Timing matters. Apply any concrete crack filler in the May through October window when temperatures are consistently above 10°C and the concrete has thoroughly dried after spring thaw. Filling cracks in late fall as temperatures drop reduces adhesion and accelerates re-opening. After filling, seal the surrounding concrete with a penetrating silane/siloxane sealer to reduce water infiltration and extend the repair life.