Trade name for cementaceous hollow roof planks

[woodypup59]

My house is 70 years old, one of a number identical is our street.

The kitchen and separate garage flat roofs are felted on top of hollow cement or concrete interlocking "planks" 15 in wide, 8 ft long and 4in thick. They are a bit like a large version of twin wall polycarbonate.

I'm trying to find a decent picture of them to show my roofer.

Is there trade name for these, has anyone any pictures of the structure ?

Thanks

Edited by woodypup59 on Thursday 12th February 10:02

[Lotobear]

Often referred to as 'Bison Beams' though that is not always strictly correct but it's the oft used 'trade' term that most builders know

Prestressed hollow core concrete planks would be the technically correct term