Its the special wooden concrete...or concrete wood....i forget
call an inspection service and they could proably recommend someone, plus if you did higher an actual inspection company it would be in writing and if problems occured later they would be liable...to some extent anyways.
Also I am far from a concrete expert but after having to re-pour a front step and walkway I learned that floors/foundations etc poured that long ago would be different than now. Different mixes and all. But one thing for sure if it was not maintained properly than it would most assuredly be weaker than required. I would mention specifics but I cannot recall exact details, only remebr if it (concrete) is not maintained properly after 5+ years it degrades quite a lot. Dunno if this was helpful but...i tried