A friends garage, Michigan. Several areas of spalling on the concrete floor. Want to smooth it out and paint. Paint will be epoxy.
Should I patch with Quickcrete Vinyl patching compound? Had another friend use Portland Cement and Sand. As this is a garage floor I am a bit more concerned.
Skim-coating with joint compound covers texture, renews old drywall and plaster, and leaves smooth surfaces ready to paint.
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Replies
Portland cement and sand won't hold. There are a number of compounds made for that. Many are epoxy based, so overpainting with epoxy paint should be no problem. Try a good masonry or industrial supply house. Industrial plants repair spalled concrete all the time that gets beat up with fork trucks.
I have used a product from Emaco, called T-430 ( I get it locally, from Stetsons building supply). Reportedly, it is used to repair damage to airport runways, among other things. I have used Sonneborn's Epoflow epoxy to prime the damaged surface and then applied the T-430. This has worked well for me in the past to repair shallow damage to concrete slabs.
At first I would have said that cement and sand alone would do it but after reading some of these posts, I vote that you should buy some non shrink grout and mix it thick with min amount of water. Air brush the surface and remove all loose material then with spray bottle of water in hand spray the spalled area and trowel on the grout and level. Let it set up a bit and retrowel to smooth finish and let dry. Guaranteed to do the job and all you need to do then is apply your epoxy compound when it's completely dry.