On Tue, 08 Dec 2009 18:36:10 -0500, aemeijers wrote:
Probably was a 2-piece metal mold- fill the bottom, stick in the rebar,
put the top on, and finish filling. They didn't have sonotube back then,
and getting stuff out of an eight-foot mold is a pain. Is there evidence
of any sort of ground-down 'mold flash' line at the mid-point?

No, nothing at mid-point. Various vertical casting lines though, which
suggests to me that they made a mold from wooden strips.

I just did some proper measuring too (that'll teach me to take a quick
look and then post in a hurry!) and they're actually 12"x16", and 11"x16"
at the top and bottom (so not 12x12 square like I said in the OP, and the
tapering's less pronounced than it looks to the eye)

I took a quick photo - see reply to Oren...

Musta been built during war when steel was in short supply or something.
I've probably been in over 1000 basements over the years, and I have
never seen formed concrete basement pillars before. Either steel or wood
or laid-up brick columns.

Yeah, the guy who did the home inspection when we bought the place said
he'd never seen ones like that before.

Lots of the construction around this area was done by the family who
previously owned our place though, and it appears they were happy to work
with whatever materials they had (our barn's rather oddball in its
construction, too). Makes me wonder if they just happened to know someone
who could supply concrete, or someone owed them a favor, so they did
that rather than using wood or metal.

12"x16" seems overkill, though. The basement walls are all poured concrete
too, 10"-12" thick; it's pretty solid down there.

One other possibility is that the pillars weren't cast in-place, but were
brought in from somewhere else and were maybe originally intended for some
other construction project. I still can't think of a good reason why
they'd need to be narrower at the bottom, though (I mean, if they had to
sit on something that was 11"x16", then why not just make them 11"x16" all
the way up...)

cheers

Jules