I need to do some repairs to the concrete surrounding our basement wood
chute; the concrete forming the chute has settled a little over the
years, resulting in gaps on the outside of the house between the chute
and the basement wall which I want to fill in.
Couple of questions:
1) Will used engine oil work as a release agent between the concrete and
wooden mold? I've got some laying around that was heading for disposal.
2) How long do molds need to be left in place? Presumably not the whole
duration of the curing process - but 24 hours? 48? (I've only ever used
concrete for doing post-work before, where the post-hole forms the mold)
Due to the fact that what I need to fill in on each side of the chute is
about 3' high, 4" wide, and a couple of inches deep at the top (tapering
to 0 at the bottom), I suspect that I need to fill as much as I can with
concrete, then make good with mortar afterwards - concrete alone won't
pour nicely into such a small space (none of it's really visible from the
outside, so it doesn't need to be cosmetically perfect).
I bet it'll ever be 100% water-tight, but anything's better than a 2" gap
that visibly leaks water every time it rains :-)