1) Concrete
Found on
https://www.crosswordclues.com/clue/hollow-core-slab
A hollow core slab, also known as a voided slab or hollow core plank, is a precast slab of prestressed concrete typically used in the construction of floors in multi-story apartment buildings. The slab has been especially popular in countries where the emphasis of home construction has been on precast concrete, including Northern Europe and social...
Found on
http://en.wikipedia.org/wiki/Hollow-core_slab
No exact match found.
