How dry does the ground need to be in order to use postcret? I'm in norcal and we've had tons of rain. The ground is real saturated at 1 1/2 to 2ft.
You should not put dry concrete mix into a hole. The wetness is really not the big thing it is the fact that you may not mix it properly meaning you will have pockets of dust as things settle. These small pockets of unmixed mix will make the concrete extremely weak and will crack or crumble apart - "a buddy had this issue one time" haha.
You mix the concrete as normal (maybe shy on the side of drier mix) and simply dump it in the hole. It will displace the water since it is heavier. I have also dammed up holes and pumped out the water while filling - this just takes a few minutes a hole and keeps the hole integrity better and keeps from getting concrete slopped everywhere.
For wet conditions I use Quickcrete fast setting. It won't cure/set in 40 mins under water but it does harden enough to hold a post and move on. Others may have personal favorites for wet conditions but I can say that using the right type is a big deal.
How do you pump it out? Dec 11, 2019 at 5:41
1@aparente001 - a water pump or wet vac. Or you can just use a hose if you can get suction.– DMooreDec 12, 2019 at 0:06
Dry enough that there is no standing water after "sprinkling" it on the ground. (It's not a structural product, (no compressive strength,) so it's not critical to structural performance.
2I have put in posts with standing water in the hole and added the mix dry. I do usually over fill but it has worked well. May 11, 2017 at 19:08
@EdBeal I doubt if you can find any agency, association, (Portland cement association), etc. that would "recommend" pouring into water is "best practices."– Lee SamMay 11, 2017 at 23:45
I believe if putting the mix in the hole dry or not pre mixed some water in the hole first works better than adding water after filling the hole with the mix. Yes the water is supposed to be potable but if there is high ground water getting the hole dry is not realistic. I have put in many fences that I used this method and as I said it worked well. May 12, 2017 at 12:55
@EdBeal If the hole is full of water, how do you measure the water? How do you control the water-cement ratio?– Lee SamMay 12, 2017 at 14:52
2The mix displaces the water its a post not a structural member some water in the hole works better than trying to add water after the mix is in the hole especially with clay. May 13, 2017 at 3:44