Spalling looks like patches of the surface flaking or peeling away in irregular sheets — not the tight little craters of pitting, but broader areas where the top layer of concrete has separated and lifted off, often leaving a rougher, lighter-colored layer underneath. It usually starts small, at a control joint or a low spot where water collects, and it spreads. Left alone, this winter's small flaking patch is next winter's larger one, because every freeze-thaw cycle works on whatever rough surface the last cycle exposed.
What's Actually Causing It
Spalling comes from a handful of overlapping causes, and it's worth knowing which one you're dealing with:
Freeze-thaw expansion. Water gets into the surface layer, freezes, and expands with enough force to fracture and lift a thin sheet of concrete — the same core mechanism behind pitting, just acting on a broader area at once.
Deicing salt. Salt accelerates and intensifies that freeze-thaw cycle right where you're driving or walking, which is why spalling shows up disproportionately in driveway wheel paths and at entryways.
Finishing issues from the original pour. If the surface was over-troweled or finished with too much surface water, it can leave a thin, weak layer (sometimes called laitance) that was never as strong as the concrete underneath it — and that layer is what eventually flakes off.
Chemical exposure. Pool chemicals and de-icers both attack the surface paste chemically, on top of the physical freeze-thaw damage.
First: Make Sure It's Cosmetic, Not Structural
This is the one honest caveat worth stating up front: surface spalling — flaking limited to the top quarter-inch or so — is exactly what a resurfacing product is built to fix. But if you're seeing exposed or rusting rebar, spalling that goes deep enough to expose large aggregate throughout, or cracking that runs with the flaking, that's a structural issue and needs a contractor's assessment before anything gets resurfaced over it. Don't spray over a problem that needs to be fixed underneath first.
For the more common case — surface-level flaking on a driveway, patio, or pool deck that's otherwise sound — here's the fix.
Step 1: Remove Everything That's Already Loose
Spalled areas often have flaking material that's still barely attached. Sweep and pressure-wash the area thoroughly to knock loose anything that isn't fully bonded — if you resurface over material that's about to flake off anyway, you're just delaying the same problem by one season. Wash off all dirt and debris with a hose, use a mild detergent on any oil residue, and let the surface dry completely (up to 24 hours) before moving on.
Step 2: Fill Any Exposed Low Spots
Where flaking has left a noticeably lower patch relative to the surrounding surface, fill it with a standard concrete patch product first, per that product's instructions, and let it cure. Then roll (not spray) Like-Nu Concrete Mix directly over the repaired spot with a paint roller or sponge pad — up to three light applications, each fully dried before the next — so the patch blends into the surrounding color and texture before the whole surface gets its general coat.
Step 3: Mix and Spray the Whole Surface
Blend the two-part Like-Nu mix (Part A liquid, Part B cement powder) in the kit's bucket with a drill and paddle mixer — 5 to 7 minutes, a 20-minute rest, then 2 to 3 more minutes to finish. Strain it into a garden pump sprayer and apply in roughly 10-foot sections, spraying a light, even mist side to side rather than concentrating on one spot, ideally on a sunny day between 70°F and 90°F for the most workable dry time.
Step 4: Match Coats to Exposure
Because spalling is driven so heavily by moisture and salt exposure, the surfaces most prone to it — driveways and pool decks — are also the ones that need the most coats: 3 or more, versus 2 for a patio or walkway that sees less water and traffic. Let each coat dry to the touch (roughly 30 minutes to an hour depending on weather) before the next pass.
Step 5: Seal It — This Step Matters More Here Than With Any Other Repair
Since spalling is usually a moisture-and-salt problem in the first place, sealing after the final coat isn't optional polish, it's addressing the actual cause. Allow 2 to 3 hours after the last coat, then apply a concrete sealer. Reseal driveways every 1 to 2 years given tire wear and salt exposure; pool decks and patios can typically go 3 to 4 years.
Why Like-Nu Specifically Fixes This — Not Just Covers It Up
It matters what you resurface with, because spalling is fundamentally a moisture problem, and a lot of resurfacing products just set up the next round of it. A topical overlay or coating forms a film across the surface — which means the same trapped moisture that caused your original spalling now has a barrier sitting on top of it, building pressure underneath until that new layer blisters and lifts too. You'd have spent a weekend re-creating the exact mechanism that caused the problem in the first place.
Like-Nu doesn't work that way. It's a modified cement formula that penetrates into the slab and cures as part of it, rather than forming a separate film — so the concrete keeps breathing the way it always did, and there's no trapped-moisture layer for freeze-thaw cycles to push against. That's the actual reason it's backed by a limited lifetime anti-peel warranty: it's not a thicker or tougher coating, it's a repair that doesn't create the moisture-barrier failure mode spalling and peeling both come from. Fixing spalling with Like-Nu isn't just restoring the look — it's removing the mechanism that caused the damage.
Catch It Before It Spreads
Spalling that gets addressed early — while it's still a small flaking patch — is a straightforward resurfacing job. Spalling that gets left alone for another few winters just gives the next freeze-thaw cycle a rougher, more exposed surface to work on. Under $1 per square foot and a single afternoon is a lot cheaper than letting it become a bigger repair, or a full replacement, later — and unlike a topical patch, it won't hand you the same problem again in a year or two.
See coverage and full details on the Concrete Mix 400 Restoration Kit page, or call (949) 333-4230 if you're not sure whether what you're looking at is cosmetic spalling or something that needs a structural look first.
This ties back to the same underlying issue -- see Why Your Concrete Patch Still Looks Like a Patch for why patches and coatings fail to blend, or How to Match New Concrete to Old for the color- and texture-matching technique if what you're dealing with is a mismatch rather than flaking.
