How to Fix a Cracked Driveway Concrete: Step-by-Step Guide

Driveway cracks are inevitable in concrete — the material is strong in compression but brittle under tension and movement. Left untreated, a hairline crack becomes a quarter-inch gap within a few winters as water infiltrates, freezes, expands, and widens the void.

Driveway cracks are inevitable in concrete — the material is strong in compression but brittle under tension and movement. Left untreated, a hairline crack becomes a quarter-inch gap within a few winters as water infiltrates, freezes, expands, and widens the void. Fixing cracks early is far cheaper than replacing a slab.

Understanding Crack Types

Not all cracks are equal:

• Hairline cracks: Surface-only, less than 1/16 inch wide. Often cosmetic and easy to seal.
• Shrinkage cracks: Common in driveways under five years old. Usually straight or slightly diagonal, under 1/4 inch wide, and stable.
• Settlement cracks: One side is higher than the other, indicating the subbase has shifted. These may need more than just filler.
• Structural cracks: Wide, branching, or accompanied by significant displacement. These require professional evaluation.

This guide addresses the first two categories — the most common types homeowners encounter.

What You’ll Need

• Pressure washer or garden hose with high-pressure nozzle
• Wire brush and cold chisel
• Shop vacuum
• Crack filler (polyurethane self-leveling sealant or vinyl patching compound)
• Putty knife or trowel
• Concrete sealer
• Safety glasses and gloves

The Quikrete Polyurethane Self-Leveling Sealant is a widely available and reliable product for cracks up to 1/2 inch wide. For larger voids, Quikrete Vinyl Concrete Patcher fills and bonds well to existing concrete.

Step 1: Clean the Crack Thoroughly

Filler will not bond to dusty, greasy, or wet concrete. Start by pressure washing the entire driveway — at minimum the cracked section — to remove dirt, oil, and loose material. Let it dry completely (at least 2 hours in warm weather, longer in humidity).

Use a wire brush to scrub inside the crack and dislodge loose chunks of concrete. Follow with a cold chisel and hammer to knock out any crumbling edges — this creates a clean, stable surface for the filler to grip. Vacuum out all dust and debris.

Step 2: Widen Narrow Hairline Cracks (Optional but Recommended)

For very fine cracks, filler can bridge the surface without penetrating to fill the full depth, which leads to early failure. Use an angle grinder with a diamond blade or a circular saw with a masonry blade to widen the crack slightly into a “V” or “U” shape — this is called “chasing” the crack. Clean out the new debris with compressed air or a vacuum.

Step 3: Apply Backer Rod for Deep Cracks

If the crack is deeper than half an inch, press foam backer rod (available in various diameters at hardware stores) into the crack before filling. This limits the depth of filler needed and creates a proper two-sided bond for flexible sealants, which improves long-term performance.

Step 4: Fill the Crack

For narrow cracks, cut the tip of the polyurethane sealant tube at a 45-degree angle and load into a standard caulk gun. Run a bead of sealant along the crack, slightly overfilling. The self-leveling formula will settle flush on horizontal surfaces. Smooth with a putty knife if needed.

For wider cracks using vinyl patching compound, mix per package directions (some are pre-mixed, some require water). Pack the compound firmly into the crack in layers if the void is deep, tamping each layer before adding the next. Finish flush with the surrounding surface using a trowel. Feather the edges to minimize the seam.

Step 5: Allow to Cure

Keep vehicle and foot traffic off the repaired area for the full cure time specified on the product label. Protect fresh repairs from rain for at least 4–6 hours.

Step 6: Seal the Driveway

Once repairs have fully cured (ideally 48–72 hours), apply a concrete driveway sealer to the entire surface. This locks the repair in place, protects against water intrusion, and gives the driveway a uniform appearance. The Foundation Armor Concrete Sealer is a penetrating formula that doesn’t leave a glossy film and holds up well in freeze-thaw climates.

Apply sealer with a long-handled roller in two thin coats, allowing the first to dry before applying the second.

Maintenance Going Forward

• Inspect your driveway every spring after the freeze-thaw season for new cracks.
• Reapply sealer every 2–3 years or when water no longer beads on the surface.
• Avoid using rock salt for de-icing — it accelerates concrete spalling and crack formation. Sand or kitty litter are safer alternatives.

Catching cracks early and filling them properly keeps a concrete driveway in service for decades.

Related Reading

• Concrete Driveway Cost — full replacement costs if cracks are beyond repair