The Collaborative International Dictionary of English v.0.48:

Ferro-concrete \Fer"ro-con"crete\, n. (Arch. & Engin.)
   Concrete strengthened by a core or foundation skeleton of
   iron or steel bars, strips, etc. Floors, columns, piles,
   water pipes, etc., have been successfully made of it. Called
   also armored concrete steel, and most commonly reenforced
   concrete.
   [Webster 1913 Suppl. +PJC]