I have a few protrusions for my gas line, hose bib, and sump line that run through my poured concrete foundation. All 3 holes are above grade and were covered with putty by the builder since 03. I noticed that the carpet tack strip directly underneath those areas is slightly rusted indicating some water getting in or condensation between the wall where the cold and warm air meet.
What's effective way to fill those protrusions in? I was thinking Great Stuff expanding foam, which states that it's water resistant if water indeed is the culprit.
There are a number of products that will do the job, urethane foam is one, polyurethane caulk is another. There are a variety of cement and epoxy based putty type products that also work. Whatever you use, force it back into the hole so it surround pipes, crevices, etc. Some of these products don't work well on a damp surface.