Yes, I did it and regret it...I squirted some low expanding foam inside drilled plug holes (prior insertion of plugs and screws). Inserting the plugs and screwing the screws was ok (it felt tight and smooth) but once the foam dries out there is no way you can undo the screws.
I don't know if the foam improves stability and strength (I was dealing with breeze blocks) but unless you need the screws permanently fixed in a certain position I'd recommend not to use the foaming stuff.
DON'T squirt expanding foam inside drilling holes!!
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