The reason one keeps concrete wet is so that it doesn't dry. Covering
it with plastic does the same thing but in cold weather this isn't
much of a problem. Covering it with plastic will help keep it warm,
though, and a couple of bales of straw will help even more (and the
plastic will keep the straw out of the concrete).
On Sat, 22 Dec 2012 05:11:25 -0800 (PST), andyeverett
I don't think you need to do much besides put a blanket over the top
of it. Looks like at worse the temp will drop to freezing but that's
AIR temp, I assume you are putting the concrete in the ground. The
concrete is going to generate heat as it hydrates so it's going to be
self heating. You've actually got just about the best possible
conditions for getting a good hunk of concrete since a slow cure
produces better strengths and less shrinkage and cracking. Basically,
as long as the concrete doesn't freeze you're all set and the only
part that could possibly freeze would be at the surface and with the
self-heating of the concrete I don't even think that's a realistic
If you are going ahead and doing this, and if it is not too late to ask,
maybe you could take some photos of various stages of the hole digging and
concrete pour process etc. and post them here. It would be interesting to
see how the project worked out.
The posts above that recommend going deeper are right. Two feet down and two
feet wide is shallower than I'd recommend.
Now, it's a pain in the butt, but if you really want resistance to toppling,
don't use a round hole. Ideally you want a pyramid, nice square sides that
widen as you go down.
Get some neighborhood kids and a shovel or too, and go down three feet minimum,
with nice square sides, and that basketball hoop will be secure for a long time.
Again, thanks for all the help. Too late for pictures but I can
describe the process. The hole went down about 26 inches, was about 22
inches in diameter at the top and about 28 inches at the bottom. Per
suggestion the hole was somewhat tapered to resist frost heave and
also the widened base of the hole will resist rotation better(?). I
sweated out the hole in under 2hrs. The first 6 inches or so was soft
top soil but then got progressively more dense. At the bottom of the
hole the earth was so dense that a 20 pound breaker bar would only
chip away at the earth. The earth at the bottom of the hole was so
dense and hard that (it had rained very long and hard a couple of days
previously) I can't imagine it holding enough water to cause much
frost heave. I'm guessing frost heave depends on the soil type?
The inside of a drywall bucket was marked with several reference
lines, the bucket was filled to the line where I thought the right
amount of water would be needed. After several bags of concrete I got
the right amount of water dialed in. This way I could add nearly all
the water that was needed at once thus speeding up the mixing process.
As was suggested my concrete was a bit on the wet side but if concrete
is too dry there will be air pockets even with some poking and
aggitation. I did add about a shovel full of extra cement to the mix.
To see the instructions for the basketball setup see,
I hung a 100 watt bulb inside the metal tube clamped just above the
bottom (heat from the inside as suggested) on the top of the concrete
sat two aluminum reflector lamps also with 100 watt bulbs. On-top of
this was placed about 2/3 cubic yard of fiberglass bat-insulation that
another costumer wanted thrown away. The insulation was covered with a
tarp and anchored with many concrete blocks. This all was done on
Sunday and today (Wednesday morning) I went back to proceed with the
next step (bad design, must fill the post assembly with concrete
nearly to the top). I was worried that with too much heat I risked
melting the plastic insert (what a nightmare that would have been) I
uncovered everything and found the concrete toasty warm, not hot but
warm to the touch (I should have placed a thermometer inside). And
everything was toasty warm with only 1 100 watt bulb still working!
The bulb inside the metal tube shattered, maybe it got wet and the
smaller of the two reflector lamps had a "melt down", it got too hot
If I had this to do again I would have gone deeper as suggested but
the concrete for this project lies on very dense soil so I do not
think I will be getting a call-back (knocks on wood).
One final caution.
Steel surrounded by soil is electrically different from steel surrounded by
concrete. I don't know the physics of why, but it is.
So. If your pole is in concrete, and somebody piles an inch or two of diret on
top, there will be a voltage differential between the two lengths of steel.
That will corrode through the pole right at that point.
We've all seen it with clothesline poles. They're commonly set in concrete with
dirt over them and grass up to the pole. They all break off at the interface
between concrete and dirt, while the rest of the pole is still solid.
The instructions you posted say to mound the concrete for drainage. That will
work, mounding dirt will not.
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