Concrete questions need to be asked after Florida building collapse
by Hans Weinhold
Just some thoughts on the building that collapsed in Surfside, Florida.
I worked on a highrise building in Hamilton back in 1975. That building was unique.
I was installing kitchen and bathroom exhaust systems in that building, and part of my job involved attaching the exhaust boxes to the ceilings. If you live in an apartment building, you will know the exhaust boxes are what is behind the grills in your kitchens and bathroom.
I would use a Hilti gun, or a RamSet to fasten the boxes to the concrete. I pulled the trigger, which ignited a charge, which drove a piston, which drove a steel pin into the concrete.
The thing that was unique about this building was that sometimes when I pulled the trigger, the piston would blow right through the box and into the ceiling, and a cloud of concrete dust would fall back in my face. I had hit a hollow spot in the concrete. This happened often.
In this case, in order to get the boxes to attach to the ceiling, I would have to move the box to a different location and try again, hopefully finding a spot where…
there was actually some solid concrete.
Even though I was supposed to fasten the boxes with four pins, sometimes I had to settle for three.
My dad was a sheet metal contractor specializing in ventilation for highrise residential apartment buildings. When I mentioned the issue to him he said, “That’s probably because they didn’t bother to properly vibrate the wet concrete.”
The vibration of the concrete, as I understand it, is intended to ensure that all of the wet concrete is properly settled before it dries and solidifies. I saw it being done many times. They would use a long snake that looked like a vacuum cleaner hose and just let it swim around in the liquid concrete.
To make a long story short, when I was driving Taxi, every time I either picked up or dropped off a fare at that building over the ensuing forty-plus years, I would think about that vibration issue with the concrete. This would have been one of the first things in my mind if I ever contemplated renting a unit there.
During my short career in the sheet metal business, I worked on quite a few high-rise apartment buildings. I don’t recall any of them having that problem, or at least having a problem serious enough that I can still remember it 46 years later.
Oh, and one other thing. I recall showing up at the site on a very windy day. I think the exterior panels containing the windows were also attached using Hilti guns; and because the building was only partially constructed, some of the floors effectively became wind-tunnels.
The wind was ripping some of these panels from their moorings and they would come sailing down to crash in the streets, with the windows violently shattering. It was pretty exciting for a 21-year-old sheet metal installer to see this shit going down. So, the concrete walls had no more integrity than the ceilings.
If the vibration issue applied to the floors/ceilings of the building, who is to say that the vertical supports are any better?
If a highrise building ever collapses in Hamilton, I bet that will be the one.
It will be interesting to hear what conclusions are reached or announced regarding the building in Surfside, Florida.
Retired Taxi driver Hans Weinhold is listed in his biography as simultaneously a Welfare Recipient at Senior’s Welfare; Self-Employed; and also, a Climate Scientist at BS Detective Services.
