[TowerTalk] Looking for some foundation advice

[jimlux]

On 5/27/20 4:34 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*.
> 


I agree, it doesn't rain much in SoCal, but I watched them place dozens 
of caisson piers one rainy spring, and they just backed the truck up and 
it came right out of the chute into the hole with the rebar. There was a 
couple guys with the vibrators on a long flexible "hose" making sure 
there were no voids.  The water just spilled over the edge of the form 
at the top as it filled.  The hard part for the concrete crew was 
placing the anchor bolts into the templates and getting it level.

(Of course, what we were bolting to the top of it wound up with the 
holes in the wrong place, but that was our screw up - a drawing that 
didn't clearly tell the fabricator which way was up. New holes created 
on site)