How can I get the 2-part epoxy smell out of concrete?

Question

Six months ago or more, my friend used a 2-part epoxy (no longer have the packaging, but it's a double-syringe with clear liquids, purchased at Home Hardware) on something, and some of it (one or both liquids) got on our basement floor, which is concrete someone had painted grey before we moved in. Well, the reaction between the epoxy and (I had thought) the paint smells like a burning rag of cat pee. After the nth cleaning of it with vinegar and baking soda, I one day just duct taped it over to at least stop the smell, since it was winter and (enough) fresh air (for this particular smell) was hard to come by in our house without central air without us freezing to death.

Today I decided to try sandpaper, and sanded down to the concrete, and no matter how much I sand I can now see the outline of the spill in a grey-brownish shadow on the white concrete, and I can still smell the damn stuff. I smell three inches away on the floor and it smells neutral. It's just that one spot, and it can stink up the whole room if I leave it.

What will take care of the smell (while not adding another smell to take care of)?

Answer 1

The easiest and most cost effective way of dealing with it is to paint over it with something like drylok. You can't really do anything about the smell itself other than removing the epoxy but you can put up a good barrier.

Answer 2

Concrete appears solid, but it is very porous. Likely, the epoxy got down into the pores of the concrete. Ways to get it off economically include taking an angle grinder wth a diamond tip and grinding it down properly (because sand paper is not enough to get through concrete), or simply painting over it with drylok or something similar. Really, any paint layer should work to cover the odor.

Another thing you could do for more extreme measures would be to glue a small circle of plastic down to create a physical barrier, and then paint over that with several layers of drylok that overlap outside the plastic layer. At a later time for more extreme measures you can go in with a diamond-tip surface grinder which will definitely take up anything you have put down, or an angle grinder with a diamond-tip sanding wheel.

p.s. like others said, the odor from drylok itself will dissipate after a few days, and by that time, you will have a barrier than should prevent the odor from causing your house to smell.