> I'd like to hear comment on something the concrete people told me when I
> put in my base. I think it might be important for those who haven't
> done it before.
> I was told that the use of the vibrator is a good idea, but that
> over-using it can cause problems with the concrete. If you vibrate it
> beyond what it takes to get it to fill in the gaps, it begins to
> separate the components of the concrete. I noticed some of that when I
> was playing with it in my pour. Keep use of the vibrator to just what
> it takes. Don't over-do it.
My concrete contractor consultant and the pumper-dude both told me:
1. Concrete ordered to be pumped is usually delivered pretty "dry",
with a small slump. The mixer can adjust it as it's delivered to the
2. If it's pumped correctly, it doesn't need the vibrator, at least
in the smallish hole I had. (Gee, it seemed really big when I dug it
by hand!) The hose is put very near the surface, and the flow sets
up a standing wave which will wet the sides of the hole, the rebar
cage, and NOT incorporate any air bubbles. They seemed convincing,
The 2.5 cubic yard pour took under 3 minutes!
George T. Daughters, K6GT
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