help identify cmu-based floor system 1

[fredneck]

Just encountered floor system of telephone swithcing facility utilizing 4" thick 24" wide x 12" long CMU blocks which have 3 ribs containing a minimum of (1) #4 continuous in groutd holes in each rib. Couldn't tell if any prestressing present. CMU has 2" concrete topping over it. Floor spans are 8"-8" clear between 12" cmu bearing walls. See attached.

Can anyone help identify this system?

 

[concretemasonry]

That looks like a proprietary concrete block floor system that I have seen.

It is probably not pre-stressed or post tension. Usually they are propped or supported until after the topping has cured, but it often is an integral part of the structural system. There may be specially formed block that allow a space for the topping to tie the block and the topping together in a structural unit.

Very common in short spans and used internationally in multi-story residences where the spans relatively short (3-4 meters). The system is also used in singe family residences with either hollow clay block concrete block or even block made of a mixture of wood shavings, sand and cement to provide thermal mass storage and comfort. I have seen the system used for years in loadbearing masonry apartments up to 7 stories.

You will probably not find an ASTM spec for the units or a code section, but some international codes do address the method of construction.

Dick



Engineer and international traveler interested in construction techniques, problems and proper design.