"Cast Stone" 3

[msquared48]

Got a project at WSU where I am trying to attach antennas to a 3" thick sloping wall panels of what the architectural wall sections term as "cast stone". There is either a CMU wall or a concrete wall to the building side of the panels, with and without air gaps. There are no shop drawings for the connections or reinforcing/strength information for the panels, and the building was constructed in 1967. The panels are 6 to 8 feet high, width unknown, obviously precast sections.

Anyone run into this "cast stone" before and have any leads as to any reinforcing/ (assumed) concrete strength, and connection details (inserts, bolted, welded)?

I am really nervous about attaching anything to this material with any Appendix D, seismically approved after-set bolts, epoxy or otherwise, without knowing more.

Mike McCann, PE, SE (WA)

 

[CELinOttawa]

Hi Mike,

Cast stone is primarily an architectural product these days, but has been used as a Structural product for centuries. In the US and Canada it was very popular in the 20s and 30s as a way to build foundations that looked like cut quarry stones.

I don't have any idea as to a panel of cast stone. In my experience (Kingston, Montreal, Ottawa) these are concrete blocks formed to make quarry size stones and very effectively used to make nice looked old foundations and retaining walls.

The product, however, is fundamentally concrete. I suspect the "CMU" you have found is actually cast concrete blocks. They would be solid, and have a distinctly architectural finish. They would also be on the way out in most jurisdictions by 1967. Reliable high temp and pressure aluminium additive CMU blocks had bottomed the price of CMU and started taking over. I would not trust it for fastening without testing. Old concrete has a way of getting new ideas (read: cracks) when you fasten to it, as I am sure you are well aware.

If you'd like I can ask my father if we have specifications for a product, but I'm afraid this would be whatever as available in Newfoundland or Montreal. Let me know if I should dig.

 

[Ron]

Mike...in my experience, "cast stone" has only enough reinforcement in it to keep if from falling apart. Usually small bars but for the flatwork you described, probably WWF. It is by no means structural and I wouldn't attach to it either. Sleeve through it and attach to masonry or concrete walls.

 

[bridgebuster]

Mike,

We have a project under construction - a 300' long exterior stairway, the parapets have a cast stone coping. I don't know if shop drawings came in yet but the fabricator is only required to provide reinforcement necessary for handling and lifting. I can check on Monday.

A few years ago, we had a project where we installed about 10,000 SF of precast panels on a retaining wall. The panels were about 4" thick (concrete with a thin stone veneer). The largest panels were 5'x20'; again the fabricator only provided enough reinforcement for lifting and handling. The panels are held in place with threaded bar. There are pockets in the panels, which are filled with grout then covered with a piece of stone after installation.

 

[msquared48]

Thanks guys. You have confirmed my suspicions.

I will find another route to mount the antennas as Ron suggested.

Mike McCann, PE, SE (WA)

 

[msquared48]

I actually did finally locate the precast panel drawings after I put on my glasses (no panel placement drawings though) and WWF and #3 edge bars are specified. Still looking for the concrete strength, but probably grade 40 steel for the #3's.

Mike McCann, PE, SE (WA)