Small contrete pot hole in front room

[bennash2007]

i, i have a small about the size of a pint jug in my front room under the laminate flooring, reason why it is like that is becasue had to have a electrical box put in there to safe zone the sockets near it before the flat was rented. I was wandering how is the best way to fill this hole, considering there is a elctrical box in there now, i presume i would still just pour concrete in there, poss just lay a panel over the top then laminate on top? or is there a pacific sealer maybe. any help would be great. Thanks

[welsh brickie]

you could do that but put plastic over it first, or fill it with expanding foam and cut the excess off when set.