How to Patch Spalled Concrete

Spalling occurs when moisture infiltrates concrete, freezes, and forces the top layer to flake or pop off, leaving an unsightly, brittle crater. While it looks like a permanent scar, you can restore a level, durable surface using modern cementitious patches that bond aggressively to existing structures. Success in this project depends entirely on surface preparation. If you apply new material over dust, grease, or loose flakes, your patch will fail within a single winter. A job well done creates a seamless transition between the old slab and the new repair, preventing further water intrusion and protecting the integrity of the remaining concrete.

Expose Sound Concrete. Use a hammer and cold chisel to chip away any crumbling or hollow-sounding concrete. Once the loose bits are gone, scrub the area vigorously with a stiff wire brush to remove all surface dust and loose debris.
Eliminate Bond-Breakers. Wash the patch site thoroughly with a pressure washer or a stiff-bristled scrub brush and soapy water. Flush all fine dust out of the cavity, as dust acts as a bond-breaker that will cause your patch to pop loose later.
Coat Every Crevice. Brush a high-quality acrylic concrete bonding agent into the cavity. Ensure the liquid reaches into every crevice and nook of the exposed aggregate.
Achieve Peanut Butter Consistency. Mix your polymer-modified concrete patch in a plastic bucket according to the manufacturer's water ratio. Aim for a consistency similar to peanut butter or thick mortar so it holds its shape while working.
Fill and Strike Level. Press the mixture firmly into the cavity using a steel trowel to remove air pockets. Overfill the patch slightly, then strike it off level with the surrounding concrete using a straight edge or float.
Blend the Finish. Once the patch begins to set, lightly drag a stiff broom or a specialized texture roller over the top to match the finish of the surrounding slab. This prevents a slick, mismatched spot on your driveway or sidewalk.