Another idea: I just went through this myself but not due to fire pop-outs. The bottom of my garage floor under and just outside the garage door had numerous little pot holes from salt damage and freezing/thawing over the years, some up to 3/4" deep, most about 3/8" deep. I don't have epoxy in my garage (it is in my basement workshop floor) and not planning to do that. So I wanted to repair without starting over with a large section of the floor, but wanted to also match the existing cement color reasonably closely so it blends in. I also wanted it to be extremely strong and tough and not fail or pop out again.
What I did was first used my little 4.5" diamond wheel hand grinder from my recent epoxy job and squared all the edges of each of the little potholes. That took a while. Then, I got some 5000 psi cement mix and also some vinyl patch cement mix and some bonding glue too. Pressure washed and cleaned all the cement, then put the bonding glue all around each pop out. Then mixed up the cement with about 1 part vinyl patch to 3 parts cement and troweled it down well. I left this higher than the floor level from 1/8" to about 3/8". (Also, the 5000 psi mix has lots of pebble rocks in it. These would have been bigger than some of the popout depressions so would stick out if that is used. This is stronger than the smooth sand mix though, so what I chose to use for strength reasons.) Kept it damp with plastic sheets over it for 7 days to cure to higher strength (key is to cure to high strengh this way or with sealer, etc). Then, used my diamond grinder again and ground the whole area flat to the level it was originally. I'll say this turned out about 95% good, perfectly smooth and flat to the original floor, with just 2 or 3 small spots I have to touch up again that got pulled out after the final grinding, probably just with the vinyl mix only there. The color all blends in quite well with the original.
I'll go through winter season number 1 in coming months and see how it does next spring, but I think it is a permanent repair. If there are other popouts coming, I can always try the epoxy/sand mortor repair, perhaps sprinkled on top with cement dust to try to blend in, but wanted to try this method above first. If I were planning to epoxy over anyway, I would just use epoxy/sand mortor mix completely and in the first place. But not planning to do that to this garage floor, so this was my low cost DIY method.
The pure vinyl patch mix is also very good stuff, but this was too large an area to just do that, and my way will be much stronger with the 5000 psi cement mix present. For very small areas, people could just use vinyl patch. It blends in very well with existing cement. Of course, it won't stain the same as the original would if that were to be done later and would stick out as different.
I also know about cement resurfacer overlay products, but I used the QuikRete form of that some years back and it all partially flaked off, so I'm not keen on that product at all. Maybe some are better than that one - don't know, but they also change the color obviously, and not what I wanted here. - Paul
