I assume that this is concrete. The speculars look wrong, though. Concrete is either really rough, or it is polished, IMHO. The flat parts are too rough for being polished but to shiny for not being polished.

A ship in port is safe; but that is not what ships are built for.
Sail out to sea and do new things.
-"Amazing Grace" Hopper

Avatar image of me done by Chidori.