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berkshireman

@sky.com

[Masonry] Fence Posts, Postcrete and water

Hello,

Yesterday we got our local diy man to redo our fence posts. He did a clean job, but he did not add any water to the postcrete at the bottom of the fence posts...

he inserted the fence post, put 40 kgs of postcrete, then just dumped normal soil on top it without adding water. He insisted not to add water even though postcrete bags has instructions to add water. Did he do something wrong? Should i go ahead and add water?

Looking forward to hear back from all those diy gurus out there.



mityfowl
Premium
join:2000-11-06
Dallas, TX

1 edit

I have 98 posts and that's not the way I handle them.

But that said I have heard that it's accepaple to do that.

Its probably wrong but I think the mix of water and concrete makes it harder.

24" is a normal hole here


Tig

join:2006-06-29
Carrying Place, ON

1 edit
reply to berkshireman

Dry setting is done because it it easier.
Moisture in the soil will cure the mix. If youR soil is very dry, then water it a bit. Don't flood it, or the post may sink or shift.



Camelot One
Premium,MVM
join:2001-11-21
Greenwood, IN
kudos:2
reply to berkshireman

A lot of the fence companies here do it that way. They claim it provides a stronger bond, allowing the post to dry/shrink a bit before the inner layer of concrete pulls enough moisture from the surrounding dirt to fully cure.

I think they are full of crap, dry setting is just easier. And it does seem to work, provided it is done at a time when there is moisture in the soil.



Ken
Premium,MVM
join:2003-06-16
Markle, IN
reply to berkshireman

Pouring the dry mix in the hole is the lazy way of setting a post. It will eventually turn into concrete, but the concrete will not have as high of a psi rating as concrete that was properly mixed with water in the first place. In the end you will have an adequate job that most likely won't cause any problems, but mixing the concrete with water in the beginning just gives you more of a guarantee that you won't have problems.



Msradell
P.E.
Premium
join:2008-12-25
Louisville, KY

said by Ken:

Pouring the dry mix in the hole is the lazy way of setting a post.

Postcrete is designed to be put in the whole dry. Normally after you put the dry concrete and the post in the hole you just pour water in on top of the dry mix.
--
Written using Dragon NaturallySpeaking


Caddyroger
Premium
join:2001-06-11
To the west
Reviews:
·Comcast
reply to berkshireman

When I lived in Mich I had a 10ft satellite dish installed. The first day they installed the post. They drilled a 6in 4ft deep hole. They placed the pole and put dry concrete around the post.I asked them should the concrete be mixed and they told me it would adsorb the water from the ground. The next day cane back to install the dish. Even when there was high winds that 10ft dish did not move.
--
Caddy


PrntRhd
Premium
join:2004-11-03
Fairfield, CA

1 recommendation

reply to berkshireman

The bigger concern when setting wood posts is getting the top of the concrete above ground level to control rotting of the post.



nunya
Premium,MVM
join:2000-12-23
O Fallon, MO
kudos:12
Reviews:
·Charter
·voip.ms
·surpasshosting
reply to berkshireman

Wooden fence posts should not be set in concrete. It causes them to rot faster.

Concreting wooden posts is a hack method to keep from having to dig to a proper depth. Essentially, they are using the concrete as ballast.

If you must use concrete, fill the bottom of the hole and several inches up the post with gravel - then pour concrete all the way to the top.

If the post hole is dug to a proper depth and properly tamp backfilled, no concrete is necessary.
--
If someone refers to herself / himself as a "guru", they probably aren't.


PrntRhd
Premium
join:2004-11-03
Fairfield, CA
Reviews:
·Comcast

Depends of the soil type and climate. Out here we have heavy clay soil and no frost line. We use concrete and treated posts but it pays to raise the concrete above the soil line and taper the top to ease the water away from the post. Dry posts make less fungal growth.


Hellrazor
Bah Humbug

join:2002-02-02
Abyss, PA
Reviews:
·Service Electric..
reply to berkshireman

and don't put a huge bell of concrete at the top of the post or the freeze/thaw cycle will push it out of the ground. The best method is to the bell of the bottom of the hole so the concrete acts like a plug.

OR

You can do what nunya mentioned but pack rocks around the post to help keep it set in place. Jam them in place with the head of a digging bar.



mityfowl
Premium
join:2000-11-06
Dallas, TX
reply to berkshireman

I dug out a couple of the neighbors ladies post (that too) that were put in dry.

They weren't even close in strength to the wet holes I have replaced.



Pacrat
Old and Cranky
Premium,MVM
join:2001-03-10
Cortland, OH
kudos:2
Reviews:
·Time Warner Cable
reply to berkshireman

I have seen and done it wet and dry. I've noticed no appreciable difference in performance. That said, when I did it dry, the soil was quite damp. And when I used a wetted mix, the soil was bone dry, even at the bottom of a three foot hole. The one thing you don't want to do if you do mix it first is get it too wet. It should be on the dry side for maximum strength. Above all, if you live where you're subject to winter freezes is make the hole bigger at the top than at the bottom. If it looks like a mushroom at all, eventually the frost will heave it right out of the ground. I usually fill with concrete to about 2-3" of the ground level, and top off the top with soil. I always use the rule of one-third in the ground, two-thirds above the ground when setting posts. If you do use the dry method, it's important that it be tamped well all around the post to eliminate voids in the concrete. I use the blunt end of my spud bar for that.
--
Keep your eye on the ball, your shoulder to the wheel, your nose to the grindstone, and your ear to the ground. Now, try to work in that position!!!



slaker

@50.138.50.x
reply to berkshireman

for strongest concrete, follow the factory recommendations.

most want wet premix, with just too little water.
as the water absorbs, the chemical reaction heats the mix and the mix gets less liquid.
AFTER the heating has stopped, add just a little more water.

that's the slaking process.

--
some tests have shown dry pour with water added to be close to strength of regular mix, other tests have shown strength only half of regular mix.

dry pour with no water added, with water absorbed from the earth, is not mentioned by the factories.

==
all of which is separate from the question of whether or not a half-strength or less mass of concrete is sufficient for whatever loads are on it. normally there aren't much loads on a post.


laserfan

join:2005-01-14
Texas
reply to berkshireman

Wow do I ever need you guys!

I have an existing split rail fence, and the two cedar wood posts at the swinging gate itself are in concrete, but the concrete is well below the surface of the soil i.e. about 8 or 10 inches (I dug the soil out from around these posts--did so because they were starting to wiggle and I want to install an automatic operator on them). The posts suffered some 1 or 2 inch diameter damage, but otherwise are still strong/sturdy maybe 8" posts and I want to keep them. I'd thought I would wrap the damaged area that I exposed with that heavy black material that is used for roof edging--I forget what it's called but it looks like tar paper. And then I wanted to "postcrete" and slope-away where before there was just soil with accompanying moisture retention thus rotting problem. Does this seem a good approach? I really do NOT want to take these posts out--I expect they can last another 10 years easy if not 20...

I also have a game fence (8' tall) with heavy 3" steel 10' posts sunk 2' into the ground, and one of them has pushed-up badly (heavy clay, rock, and caliche "soil" here) and I want to try to get it back down again. I'm thinking about sledge-hammering the inverted bell of concrete at the base, so I might get down under the post and dig out whatever is pushing-up and get the post back down again. This without disconnecting or loosening the high-tension deer fencing it supports.

Any thoughts about these issues are indeed welcome! And apologies to the OP if I've taken this too far OT!



berkshireman

@46.235.152.x

Thank you all of you for your valuable replies. With mixed replies, at least I am not confused anymore, I understand how these things work. You guys are great.



mityfowl
Premium
join:2000-11-06
Dallas, TX
reply to laserfan

said by laserfan:

I also have a game fence (8' tall) with heavy 3" steel 10' posts sunk 2' into the ground, and one of them has pushed-up badly (heavy clay, rock, and caliche "soil" here) and I want to try to get it back down again. I'm thinking about sledge-hammering the inverted bell of concrete at the base, so I might get down under the post and dig out whatever is pushing-up and get the post back down again. This without disconnecting or loosening the high-tension deer fencing it supports.

Any thoughts about these issues are indeed welcome! And apologies to the OP if I've taken this too far OT!

Your going to have to dig that up and resink it to have success.

laserfan

join:2005-01-14
Texas

said by mityfowl:

Your going to have to dig that up and resink it to have success.

Yeah that's what I meant by digging underneath it. As it stands it is actually being pulled-down by the fence it "supports" so I'm thinking if I can dig under it I can get it to drop into place. Must be popped-up at least 5 inches, breaking the weld on a cross-support!


slaker

@50.138.50.x

for laserfan,
first question, just pour the additional concrete around the damaged area. if you want you can treat that bad area first with anything water sealant, like tar or varnish or roof cement.
second question,

with a little kludging, the easiest way to excavate under the concrete is hydraulic drilling.
just get a length of 1/2" pvc pipe, to which you have glued a female hose fitting, and a shorter length of say 1" pipe, that the 1/2" pipe will slide into easily. attach a garden hose to the 1/2" pipe, run the water. push them both into the soil near the post. the water will loosen the underground soil, and the water with the soil will come up and out through the gap between the two pipes. when the excavation is big enough, the post with concrete will settle by itself.


laserfan

join:2005-01-14
Texas

Thanks a lot slaker for your replies. I'd have never thought of "hydraulic drilling". I may have some trouble getting water to the site, and I expect the rockiness may cause it not to work, but it's worth a try for sure.

We certainly have had a very extended period of drought here (several years now) and while I'd hoped for heavy rains to get the posts to "settle" (I have two that are popped actually, tho one is worse than the other) the idea to inject water under pressure and flushing soil/clay out has merit. Thanks.



Hall
Premium,MVM
join:2000-04-28
Germantown, OH
kudos:2
reply to berkshireman

said by berkshireman :

With mixed replies, at least I am not confused anymore...

If it's any consolation, flip a coin and do it one way or the other and you should be okay. Whatever route you take, no need to tell anyone here lest those who said to do it the "other" way will give you grief.