flex 450 concrete
 

flex 450 concrete
has anyone ever heard of flex 450 concrete? supposedly it is a flexible, waterproof concrete, reportedly used by the army corps of engineers. i can't find anything on the net. any leads would be appreciated.
i am not sure, but there may have been a article in aci, i recall the photo of the thin concrete slab flexing under
test apparatus loading. concrete international perhaps.
i've heard of flex 650, a typical pavement design.