View Full Version : 900 deep post, water seeping in
23rd Oct 2011, 04:58 PM
just about to dig a 900 deep hole to put a colum in. Am a bit worried, water will seep in. If I pour concrete in, it may mess it up? Should I build soe formwork? Or throw something in like a bucket so the water stays outside and pour the concrete inside?
23rd Oct 2011, 05:22 PM
The main thing with damp ground is to concrete the post in the same day (preferably straight away) as digging the hole least the sides start to collapse in. Bail out the bulk of any water seeping in then put in the post and throw in the concrete, the material will displace any water and prevent anything else seeping in and will dry without any trouble. Many wouldn't bother bailing out the surplus water and would just fill, don't put in formwork it will be counter productive.
23rd Oct 2011, 08:06 PM
seems I got lucky, its a bit moist bot not like in the backyard where water seeps in as soon as you dig 100mm deep. Weird. At 800 now, pretty solid down there....
23rd Oct 2011, 08:16 PM
Famous last words ...
23rd Oct 2011, 09:59 PM
Famous last words ...
Thats what I love about this forum. Supportive, positive and encouraging. On the reno shows they dig a hole bung in the post pour in a bag or two of premix and shove the water hose in for a bit. Whats the problem?
I know the situation. I had massive rabbit burrows and Tasha digs (SWMBO's dog who is trying to emigrate to China the hard way) in my implement shed, under my metal stash of course. It was funny to see these holes full of water to within about, oh 100mm from the surface.
I usually drive in posts so I am not much help. I can agree that formwork is not a good idea. The purpose of concrete is to fill gap between post and soil and if soil is disturbed it will not grip properly. This comes back to driving in posts. Must be done right or the post will pull out. This is with stock type fencing but the grip is still important. The post should grip the soil around it. Best stability is with a tight grip. Otherwise you just have a heavy weight holding the post down. NB this is a non-professional opinion only.
24th Oct 2011, 01:49 PM
I'm just wondering why you are going down 900mm. Do you have very sandy soil?
25th Oct 2011, 11:15 PM
On the reno shows they dig a hole bung in the post pour in a bag or two of premix and shove the water hose in for a bit. Whats the problem?
they spraypaint on top of a rusty fire place too, don't even brush the cobwebs off. Fireplace meant to be used...
The water will not penetrate into the concrete, you would have to stir it. Plus 2 bags won't do it at 800mm, except in the block. That's why I am not watching this.
I'm just wondering why you are going down 900mm
classified as highly reactive, code says 800, may be 900 soon. Supporting the front porch, 5mē concrete tiles.
Suppose the renovators did the old column, concrete pad was ok, then bricks. No mortar between the bricks. or maybe once, but quite yellow stuff, suppose a little more cement would have done the trick. Maybe spent it all in the 100mē driveway. Suppose driveway is more important then the load bearing column which then went down by 40mm....
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