is the slab good enough for coating?

During a recent site visit, I was confronted with a particularly bad slab in a garage and asked if I thought it was good enough for a resin floor coating. If it was, what would I recommend as the best way to proceed?

I thought this was a great example to discuss with the global resin flooring network as we all would've seen similar slabs before, but we might have slightly different opinions on how to tackle it (if at all).

Below is a couple of photos showing the slab halfway through surface preparation. You can see there's an existing grey coating that has partially peeled/flaked off, and the concrete is heavily pitted in some areas.

A close up shows that the existing coating wasn't very strong (possibly a water-based epoxy), and from the look of the concrete underneath, there's a question mark on whether it was prepared before the coating was applied. 

Below is a close up the prepared concrete and a spot where I had a bit of a dig with a chisel to see how soft the slab was.

So, what do you think? Is the concrete suitable for resin flooring? If so, how would you go about installing the flake floor the client was hoping for?

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Gary Johnson wrote:
29 May '20 8:09am
Tap with a steel rod to check for soundness

If ting ting go ahead

If a dull thud no

Check compressive strength min 25 Mpa

Check pull off strength min 1.5 Mpa

If both ok proceed

Check if effective DPC is under the slab

If yes, continue

Check for cracks and discuss with client what can be done and what can’t be done

Remove and repair unsound concrete with Epoxy mortar or putty as appropriate

Grind the surface


Prime with solvent free Epoxy primer

Allow to cure

Fill blow holes imperfections with quick set Epoxy putty

Allow to cure sand smooth, vacuum

Apply 250 micron solvent free pigmented scraper coat

Allow to cure

Sand smooth

Fill blow holes with quick set Epoxy putty

Allow to cure

Sand smooth


Solvent wipe

Surface must be perfect at this stage

Apply final coat of 750 micron solvent free pigmented self leveling Epoxy

Allow to cure

Cut and seal joint

Allow full cure of joints and floor

Open to traffic
Resin Jack replied with:
30 May '20 6:08am
Thanks Gary for the awesome response!

So you would do a tensile pull off test and also use a rebound Schmidt hammer to check tensile and compression test for a garage project? (keep in mind limited project price)

We could not get access to see if the slab had a sheet under it, does that mean you would rely on moisture meters (probe or capacitance) to reassure yourself for moisture?

Keep smiling @resinjack