On 05/27/20 19:34 PM, Steve Maki wrote:
On 05/27/20 19:15 PM, Grant Saviers wrote:
Actually it is ok to pour concrete into a wet hole if the concrete is
pumped in from the bottom. The water rises right out. Not ok to drop
concrete into water. The mix plant, pumper and driver know how to
adjust the mix a bit.
Hmm - that's not my experience. When we (drillers hired by me) install
caissons for tall monopoles and self supporters with 30'-50' deep
caissons, they just dump the concrete in. They use temporary cylindrical
forms to prevent cave-ins, but pay little attention to the water down
there. These operations are always monitored by 3rd party engineering
firms. On the reports I usually see *freefall concrete placement*.
Or have a PE design a different base, there are all sorts of
alternatives, plates, piers, wider and shallow, etc. As long as the
base resists the overturning moment and shear. The stock foundation
UST wet stamp is on the web so should be a easy and quick job for a PE
(unless they want a soils test, which in theory... but local
knowledge of conditions often is acceptable).
Agreed. A suitable foundation can be designed for above ground placement
if you don't mind the ugliness and the concrete cost. The key is to get
it engineered properly.
In fact there are many 70'-100' cellular monopoles around Detroit on
ballast mounts. Often to avoid what is beneath the surface.
-Steve K8LX
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