What Happens to Slab Cracks and Joints Before Epoxy Goes On

Run a fingernail across every crack in the slab and note which ones catch. The ones that catch have moved, and riverside epoxy flooring ruts n guts covers how those get treated before any resin goes near them. Tract-home garages across Riverside, CA often have a hairline crack or two from curing, and epoxy will not hide them, so each crack is dealt with during prep.

Which cracks are only cosmetic?

Hairline cracks from shrinkage as the concrete cured are narrow and flat, with both edges at the same height. They are cut open slightly with a grinder blade or a crack chaser, cleaned and filled with a low-viscosity epoxy or a polyurea crack filler. Once the filler is cured, it is ground flush so the floor above it stays smooth.

What about cracks where one side has dropped?

A crack with a step, where one side sits lower, means the soil under the slab has settled. Filler holds the edges together for a time, but if the ground is still moving the crack will come back. Slabs in Jurupa Valley and the lower parts of Riverside County that were poured over poorly compacted fill are the usual cases. A repair is done with a semi-rigid filler and the homeowner is told the line may reappear.

What are control joints for?

Saw cuts across a garage slab are there on purpose, so the concrete cracks along them rather than anywhere else. They are filled with a flexible joint filler, not rigid epoxy, because a rigid fill will crack the moment the slab shifts. The joint is cleaned of dust, a backer rod is pressed in if it is deep, and the filler is tooled flush. The base coat and topcoat go over the filled joint, and a hairline may show through over time, which is normal.

How are spalls and chipped edges repaired?

A spall is a piece of the surface that has broken away, often at a joint edge or around an anchor bolt. It is ground back to solid concrete and patched with a repair mortar that matches the slab. A feather-edge patch under a thin coating shows through, so deeper spalls are filled in lifts and ground flat again.

Does the patching change the finish?

A patched floor under a solid color or a heavy vinyl flake broadcast hides the repair well. A clear coat or a metallic pigment finish shows every one, so those finishes need more careful repair, or a skim of cement-based underlayment over the whole slab.