Chipped, flaking, or scaling concrete doesn’t just look bad — it’s a sign that the surface is breaking down due to weather exposure, poor curing, or freeze-thaw cycles. If ignored, it can lead to deeper spalling, corrosion of reinforcement, or full slab failure. Thankfully, most surface-level damage can be repaired successfully without removing the entire slab. This guide walks you through exactly how to diagnose and fix flaking concrete properly — so it stays fixed.
Start by testing whether the chipping is only surface deep or if it’s beginning to spall. Tap around the affected area with a hammer — hollow sounds often indicate deeper delamination. If damage is limited to the top few millimetres, a surface patch will suffice. If you see crumbling edges, rust-stained cracks, or deeper breakaway, you may need to remove and rebuild a thicker section. Never just skim patch over loose concrete — it’ll fail again fast.
Use a cold chisel and hammer or angle grinder with a diamond grinding disc to remove all loose flakes and weak concrete. Cut out to solid edges with a slight undercut to help hold your repair. The patch area should be clean, sound, and not feathered too thin. For best results, grind or scarify the full surface area to a depth of 3–5 mm beyond the edge of damage. Vacuum up all debris once done.
Use a pressure washer or wire brush to scrub the prepared area thoroughly. If there are signs of efflorescence, mould, oil, or salt damage, use appropriate cleaners (citric acid, degreasers, etc.). Flaking concrete is often made worse by contaminants — you don’t want them interfering with the patch bond. Once cleaned, rinse and allow the surface to dry completely before proceeding.
Many patch products require either a bonding primer or water pre-wetting (for cement-based mortars). If you're using a polymer-modified mortar, follow the instructions exactly — too much or too little moisture can weaken adhesion. Apply bonding slurry or primer into the patch area using a stiff brush. Avoid letting it dry before applying your repair mix unless your product specifically instructs it.
Mix your repair mortar (polymer-modified, rapid-set, or commercial patch compound) according to instructions. Apply with a steel trowel, pressing it firmly into the prepared area and building up slightly proud of the surface. Feather the edges only if the product is rated for feathering — many are not. Aim for a smooth, even finish, and shape to match any slope or drainage lines the slab originally had. Avoid applying too thinly — most patch failures occur when applied less than 5 mm deep.
Once the patch is finished, cure it just like fresh concrete. Use curing blankets, plastic sheets, misting, or curing compounds depending on the setting. Most surface patches fail because they’re allowed to dry out too quickly. Curing is especially critical if you're repairing an outdoor slab in direct sun or wind. Give the patch 3–5 days minimum (or per product instructions) before exposing to water, freeze, or load.
Once cured, seal the entire slab or patched zone with a high-quality concrete sealer. Choose a penetrating silane-siloxane sealer for exterior work (especially driveways and patios), or an acrylic sealer for interior slabs or decorative surfaces. Sealing helps prevent freeze-thaw damage, water ingress, and salt absorption — the very causes of flaking to begin with. Reapply sealers every 2–4 years depending on wear and exposure.
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