I have 60 concrete slabs in Deluge and cannot build the concrete bridges

[Komrath]

Also the concrete slab factory is not operational and I have no idea how to enable it. Sometimes this game makes no sense whatsoever

[Spliff]

Sounds like the factory needs power. You can see and start this activity at infrastructure

[Plagen]

You need the factories operational before you can build bridges with those resources. Wood bridges should be unlocked, use logs if you need bridges for now.

[shadow82]

There is no need for any other kind of bridges. Only advantage of concrete ones is the big wide one that is twice as long as a regular bridges. It is not needed on Deluge, so you can stick with wooden one. And well, you swim into woods on that maps (pun intended).