Garage Concrete Prep, Crack & Pit Repair in Cincinnati, OH

Crack Repair: Not All Cracks Are the Same

“Can you fix the crack?” is the first question most people ask, and the honest answer depends entirely on what kind of crack it is. Lumping them together is how installers end up with a repair that reads straight through the finished floor a year later.

• Hairline shrinkage cracks. Thin, meandering, no height difference between the two sides. These form as fresh concrete cures and gives up water — nearly every slab has some. They are cosmetic. We open them slightly, fill with a low-viscosity repair resin, and grind the repair flush so it disappears under the coating.
• Wider settlement cracks. Anything you can catch a fingernail in. These get chased out into a V or a saw kerf, filled with a semi-rigid polyurea or an epoxy repair mortar packed with sand so the fill has body, then ground flush. Filling a wide crack with thin resin alone just lets it sink and telegraph.
• Active or structural cracks. One side sits higher than the other, the crack runs wall to wall, or it has visibly moved over the years. A coating is not a structural repair, and no floor system will hold a moving slab together. We will repair and coat it so it looks right, but we will also tell you plainly that the crack can return — and if what you actually need is a concrete contractor rather than a coating, we would rather say so at the estimate than after your deposit.
• Control and expansion joints. Those straight, tooled lines were cut on purpose to give the slab somewhere to move. Filling them flush and coating over the top gives a seamless look, but on a slab that genuinely moves, honoring the joint instead is the longer-lasting call. We make that decision with you rather than defaulting to whichever is faster.

One thing we never use: hardware-store concrete caulk or vinyl patch. It stays soft, shrinks as it dries, doesn’t bond to a ground profile, and shows through the topcoat as a visible line — which is why so many DIY repairs have to be ground back out before we can coat.

Pitting, Spalling, and Popouts — the Ohio Special

If your garage floor looks like the top layer is coming off in coin-sized flakes and shallow craters, that is spalling, and around Cincinnati it usually traces to the same story: de-icing salt carried in on your tires melts onto the slab, soaks into the surface pores, and then the freeze-thaw swing expands it and pushes the surface off from the inside. Slabs that were finished with too much water in the mix, or sealed before they had properly cured, give up their surface fastest.

Spalling looks alarming but it is usually a surface problem sitting on sound concrete underneath, which is why most of these floors are very much still coatable. The repair sequence is:

1. Grind the whole slab to get past the weak, dusting surface layer down to solid concrete.
2. Trowel a polymer-modified patching compound or an epoxy mortar into the pits and craters, slightly proud of the surface.
3. Re-grind the patches flush once they have set, so the floor reads as one plane.
4. Coat — and let the flake broadcast do the rest of the work, because a full flake layer is remarkably good at disguising the minor texture variation a heavily patched slab keeps.

What does not work is coating straight over a pitted floor. A thin film follows the shape of what is under it, so every pit and crater telegraphs through as a dimple, the low spots pool extra material and cure differently, and the coating has nothing solid to grip where the surface is already failing. Skipping this step is the single most common reason a cheap quote comes in cheap.

What Diamond Grinding Is Actually For

Grinding is not about cleaning the floor — it is about creating a concrete surface profile, an intentional roughness the coating can key into mechanically. The industry rates that texture on a CSP scale, and thin-film garage systems like ours generally want something in the CSP 2–3 range: opened pores and visible tooth, not a polished sheen and not exposed aggregate.

Grinding does three jobs at once:

• Removes laitance — the weak, fine layer of cement paste that floats to the top during finishing. Coating onto laitance means the coating is bonded to the weakest millimetre of your slab.
• Strips what is already there — old sealers, curing compounds, mastic, paint, and failed coatings. Sealers are the quiet killer: they are invisible, most homeowners don’t know a builder applied one, and nothing bonds through them.
• Opens the pores so the primer coat can sink in and anchor rather than sit on top.

This is exactly why we don’t acid etch. Etching is a chemical wash that reacts unevenly across a slab, cannot touch a sealer or an oil-soaked patch, and leaves behind residue and loosened material that has to be rinsed and neutralised. It produces an inconsistent profile at best, and it is the most common single cause of the peeling floors we get called out to grind off. We also grind dust-controlled — vacuum-shrouded machines pulling the dust at the disc — because a garage grind unmanaged puts concrete dust through the door into the rest of your house.

Oil, Grease, and Contamination

That dark patch where the car has parked for fifteen years is not a stain on the surface — it is oil that has wicked down into the concrete, and it will keep migrating back up toward a fresh coating and break the bond in exactly that spot. Grinding alone doesn’t solve it, because you can grind off the discoloured surface and still have contaminated concrete underneath.

Deep spots get degreased first and given time to draw out, then ground, then checked again. Occasionally a spot is saturated far enough down that the right answer is to remove that concrete and patch it. We would rather find that at the estimate and price it honestly than discover it mid-install — and it is one of the reasons we want to look at your actual floor rather than quote a square-foot number over the phone.

Below-grade slabs bring a different contaminant: water vapor moving up through the concrete continuously. We cover how we test for that, and what changes when the answer comes back high, on our basement and patio floor coatings page. Shop, warehouse, and service-bay slabs add hot-tire traffic, forklift wear, and chemical exposure on top of all of the above — that work is on our commercial epoxy flooring page.

When Prep Is Most of the Job

On a bare, sound, recently poured slab, prep is a morning’s work. On a forty-year-old garage floor with a failed coating, salt spalling, oil contamination, and cracks, prep can genuinely be the majority of the labour on the job — and the coating itself becomes the quick part at the end.

That is worth understanding when you compare quotes, because prep is invisible in the finished floor and therefore the easiest place for a cheap bid to cut. Two quotes on the same garage can differ by thousands purely on whether the slab is being ground and repaired or simply rinsed and painted. The floors look identical the week they go in. They look nothing alike in year three.

If you are weighing quotes right now, our Cincinnati cost guide lays out typical market ranges and exactly which prep line items to ask each installer to spell out. And if a previous coating has already failed on you, the specific failure modes — and which are prep-caused — are broken down in will a coating yellow, peel, or fade.