Here are some more photos, taken near the end of last week, when the remainder of the walls had been demolished. The old plaster ceiling is coming out these next few days, so I’ll post photos of that later on this week and next. One of the interior (formerly an exterior, see photo of piece below) walls was a combination of cinder block, then terra cotta block, with steel rebar rods run all the way through, then filled with concrete- I guess with older buildings, you never really know what you’re going to run into. The concrete has been quite a challenge as well; it’s probably 5,000 to 7,000 PSI based on how it has behaved with a power chisel. Most foundation, slab, and wall concrete mixes are now typically in the range of 3,000 to 5,000 PSI, so the pours done here in 1922 are probably portland cement with a coarse stone aggregate, which is commonly used for applications where the concrete is exposed to freeze-thaw cycles, so in this case, it would make sense for the exterior walls and structural elements.
Interesting fact- the concrete mix for One World Trade Center’s supporting columns and walls (the building has a central concrete tower, like a vertical bunker) was invented solely for the project, and the higher-range pours have a tested strength of 14,000 PSI.