You’re usually here because your exposed-aggregate concrete has crossed a line: it doesn’t just look dated, it’s pitting or shedding stones. If the slab’s surface has failed or the concrete is still moving, overlays won’t hold and you’re in replacement territory.
In this guide, you’ll learn the red flags that turn exposed aggregate concrete repair into a short-term patch instead of a lasting fix. They just kick the can down the road. You’ll also get plain-English questions to ask contractors so you can tell the difference between a true fix and a “make it pretty again” bid that’s likely to crack or delaminate right back through.
Replacement-Only Triggers
A homeowner gets quoted a cheap “refresh,” then watches the same pits and pop-outs come back after the first winter—and that’s often when to replace exposed aggregate concrete becomes the real question. The difference is usually visible in a handful of telltale conditions that surface work cannot outrun.
Pitting that keeps deepening is often a sign the surface paste is failing and future stone loss is likely. Read more in our article: Exposed Aggregate Concrete Pitting
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Treat replacement (or full-depth reconstruction in failed areas) as the default when the conditions below are present.
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Skim coats and “make it pretty again” sealers hide problems. They are not a fix.
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At that point, replacement is the practical move, not another cosmetic pass.
| Trigger | Quick threshold / clue | What it usually means |
|---|---|---|
| Deep spalling (not surface scaling) | Consistently > ~1/4 in deep, or repair removes > ~1/2 slab thickness | Patches/overlays won’t last; plan replacement/full-depth repair |
| Widespread delamination (hollow/drummy) | Broad connected hollow areas on tap test (often top 1–2 in) | Overlay can’t bond to a separating layer |
| Rebar exposed + active corrosion | Rust-stained cracking, exposed steel, crumbling at bars (concrete rebar corrosion symptoms) | Structural deterioration beyond decorative repair |
| Systemic distress / movement | Damage ~30%+ of surface, or slab sinking/rocking/opening gaps | Tear-out likely; fix base/drainage/voids with replacement |
Quick Field Tests at Home
Before you pay for three estimates, you can do a quick reality check. You may be looking at a surface cover-up. Even “just ugly exposed aggregate” can mean the surface is separating. Think of it as a crust over crumble, especially with turning tires and salt air.
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Depth check (spalling/pits): Use a ruler or tape measure and check the worst spots for spalling exposed aggregate concrete repair. If you’re consistently deeper than about 1/4 inch, or you can tell a repair would have to cut out a big chunk of the slab, you’re past a simple cosmetic fix.
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Tap test (delamination): Tap the surface with a hammer handle or a metal wrench and listen for exposed aggregate concrete delamination causes. Solid concrete sounds sharp; delaminated areas sound hollow or “drummy.” Mark those zones with chalk. If the hollow areas connect into broad patches, overlays usually fail because they bond to a layer that’s already separating.
Salt and de-icers can speed up scaling and spalling by pushing water into the surface and amplifying freeze-thaw damage. Read more in our article: Does Road Salt Damage Concrete
- Movement clues (settlement/voids): Look for one side sitting lower, gaps opening at joints, edges that rock when you step near cracks, or a straightedge showing a lip you can catch with a shoe—classic concrete subbase failure signs. When the slab is still moving, any replacement that ignores the base and drainage is a redo waiting to happen.
When slabs sink or rock, the real failure is often below the concrete in the base, drainage, or voids under the slab. Read more in our article: Concrete Driveway Sink Causes
What to Ask in Estimates
A vague scope can buy you a surface makeover while the slab stays hollow or moving, which is when full replacement belongs on the table. A few pointed questions force each bid to reveal whether it is fixing the cause or just the look.
When two bids recommend totally different fixes, it’s usually because one is pricing a surface makeover. Mike Holmes would call that a bad bet. You’ll make a cleaner repair-vs-replace decision if you force the scope to match what’s actually deteriorating.
Ask each contractor:
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“How deep will you remove unsound concrete in the worst areas, and what thickness will be left?”
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“Roughly what percent of the slab is affected once you mark hollow or popped-out zones?”
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“What’s causing this here: subbase voids/settlement or salt-air chlorides and moisture?”
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“If it’s moving or hollow, what will you do to stabilize the base before any new concrete goes down?”
