Concrete Driveway Repair Guide: Cracks, Spalling, and Resurfacing

Updated April 2026 · By the MasonryCalcs Team

Concrete driveways develop problems over time regardless of how well they were built. Cracks appear from shrinkage and thermal cycling, surface spalling results from freeze-thaw damage and deicing salts, and sections settle as the subgrade compacts or erodes. The good news is that most driveway problems can be repaired rather than replaced. Knowing which repair method matches each type of damage saves thousands of dollars compared to demolition and full replacement. This guide covers the diagnosis and repair of every common concrete driveway problem.

Diagnosing the Problem

Before choosing a repair method, identify the root cause. Hairline cracks less than 1/8 inch wide are normal shrinkage cracks and are primarily cosmetic. Wider cracks may indicate subgrade movement, tree root pressure, or structural overloading. Cracks that run in a straight line along a control joint are performing exactly as intended. Cracks that radiate from corners or run diagonally across slabs suggest structural stress.

Spalling — the flaking or peeling of the surface layer — is almost always caused by freeze-thaw cycles on concrete that was improperly finished, sealed too early, or exposed to deicing chemicals. Settling occurs when the subgrade beneath one section compresses or washes away, creating a sunken area. Evaluate the overall condition before deciding between spot repairs and full resurfacing.

• Hairline cracks under 1/8 inch: cosmetic — seal to prevent water entry
• Cracks 1/8 to 1/2 inch: fill with flexible sealant or caulk
• Cracks over 1/2 inch: may indicate structural issues — investigate cause
• Surface spalling: topical repair with resurfacer or overlay
• Section settling: mudjacking or polyurethane foam lifting

Filling and Sealing Cracks

Clean cracks thoroughly before repair. Use a pressure washer or stiff brush to remove debris, dirt, and loose concrete from inside the crack. For cracks 1/4 to 1/2 inch wide, use a flexible concrete crack filler or polyurethane caulk that remains pliable through temperature changes. For narrow cracks under 1/4 inch, a liquid crack sealer that flows into the crack by gravity works well.

For wider cracks or cracks with significant depth, fill the lower portion with backer rod foam before applying the sealant. This prevents excessive material consumption and ensures the sealant forms a proper bond at the correct depth-to-width ratio. The sealant should be slightly below the surface level so it does not get peeled off by tire traffic.

Patching Spalled Areas

Spalled areas where the surface has flaked away can be repaired with a polymer-modified concrete resurfacer. Clean the area down to sound concrete by chipping away all loose material with a cold chisel and hammer. The exposed surface must be solid — applying resurfacer over deteriorated concrete results in the patch peeling off within a season.

Dampen the repair area, then apply bonding agent followed by the resurfacer mix. Build up the repair to match the surrounding surface level in layers no thicker than 1/4 inch per application. Feather the edges to blend with the existing surface. Allow each layer to cure before adding the next. The repaired area will not perfectly match the color of the original concrete, but the difference fades over time with weathering.

Lifting Settled Slabs

Settled driveway sections that have sunk below adjacent slabs can often be lifted back to level without replacement. Mudjacking involves pumping a cement slurry through holes drilled in the slab to fill the void underneath and raise the surface. Polyurethane foam injection is a newer, lighter alternative that expands to fill voids and lift slabs with less weight added to the subgrade.

Both methods cost significantly less than slab replacement — typically $500 to $1,500 per slab compared to $3,000 to $8,000 for demolition and replacement of a similar area. The repairs are completed in hours rather than days, and the driveway can bear traffic within 24 hours. However, these methods work only if the concrete itself is in good condition — they cannot fix badly cracked or deteriorated slabs.

Full Resurfacing vs Replacement

When surface damage covers more than one-third of the driveway but the underlying concrete is structurally sound, resurfacing is a cost-effective alternative to replacement. A concrete overlay system applies a thin layer of polymer-modified concrete over the entire surface, creating a uniform new finish. Overlays range from 1/4 to 1/2 inch thick and can include decorative options like stamped patterns or integral color.

Full replacement is necessary when the concrete has extensive structural cracking, multiple settled sections, or the original slab was too thin for the traffic it carries. A complete replacement costs $8 to $15 per square foot including demolition, disposal, subgrade repair, and a new pour. The silver lining of replacement is the opportunity to correct the original design flaws — thicker slab, better drainage, improved subgrade, and proper control joints.