Concrete mix in a bag.

[Mark42]

I put a 7 ft aluminum lamp post in the ground in a garden the other day. I used two 60lbs bags of concrete mix. For some reason I stopped to read the directions and it said to just dump the dry power mix in the post hole, then add water until it is all absorbed and a puddle forms on top, then let it sit until it cures.

I thought that was strange.

I mixed the concrete in a wheelbarrow the traditional way until the consitency of wet sand, not a slurry. Then dumped it in the hole and shaped a "dome" top around the post so water will run off, and no weeds will grow within 10" of the post.

It set up fine.

I was just wondering if anyone has used the concrete mix by dumping it dry in a hole and pouring water in and if it workes well that way.

 

[NelsonQ]

Re: Concrete mix in a bag.

I guess they'd know best but I've done a similar thing with the concrete and I ignored their instructions and mixed it separate as well.

I don't know how you'd mix that much with water in the hole without getting dry pockets in the concrete.

 

[SoFloStone]

Re: Concrete mix in a bag.

I was just wondering if anyone has used the concrete mix by dumping it dry in a hole and pouring water in and if it workes well that way.

I have been setting fence posts this way for almost 20 years, and never had an issue with it not setting up correctly.

in fact, my fence lasted through Hurricane Wilma and stayed standing, while the neighbors had fence sections fall down.

 

[WizeOne]

Re: Concrete mix in a bag.

It's done very commonly, especially with relatively smaller diameter fence posts here in the PNW. Even then they wait for two days before they hang the fence on them. If for any reason the water you pour in the hole doesn't get the job entirely done, then the eventually wet ground will.

Sounds like you have a pretty good size hole with two 60 lbrs. It didn't hurt to pre-mix it in that case.

 

[j_martin]

Re: Concrete mix in a bag.

Here frost footings are needed under any permanent post in the ground, such as a post for a porch or a pole barn. Procedure is to drill a 1 foot hole to the required depth, pour a bag of dry pre-mix concrete in it. Level it off, set in your 4 to 6 inch post, and back fill it. Ground moisture will shortly set up the concrete.

hope it helps
John

 

[Limited-Time]

Re: Concrete mix in a bag.

I've done it that way for years as well. Never an issue. I've even dry set post and let the concrete pull the moisture needed to set up from the ground. Have you ever seen a bag set up just laying on the damp cement floor, or the ground for that matter. Given time a bag of premix concrete will pull water from where ever it can and harden completely.

 

[Mark42]

Re: Concrete mix in a bag.

Next time I am just setting a wood post, I'll do the dry mix. It sounds like less work too. But for this aluminum lamp post in a garden where I wanted to keep weeds from growing close to the post so a weed trimmer won't be blasting the black paint off the post, I needed to be able to "form" the cement in a dome above grade so it looks nice, and sheds water.

I have three more lamp posts to set in other gardens along walkways, but they will only get one bag each, because these posts are cut down to where only 30" will be above grade, and a 13" tall traditional brass carriage lamp goes on top. I guess I'll have to hand mix the cement again to have it in a consistancy where I can form the dome I want.

Thanks for the advice!

Mark

 

[Bob_VT]

Re: Concrete mix in a bag.

Seriously consider a piece of sonotube next time...... the frost might raise hell with the rough concrete shape.

 

[Mark42]

Re: Concrete mix in a bag.

Seriously consider a piece of sonotube next time...... the frost might raise hell with the rough concrete shape.

Oh, good idea Bob! I think I have a piece of sonotube somewhere.

 

[triumphrick]

Re: Concrete mix in a bag.

I mixed the concrete in a wheelbarrow the traditional way until the consitency of wet sand, not a slurry. Then dumped it in the hole and shaped a "dome" top around the post so water will run off, and no weeds will grow within 10" of the post.

Not sure of the dry mix and then add water?? Will it soak thru? I have lots of fence posts and other concrete projects here and what you posted about "doming" is the most important aspect to setting posts/poles. Good info for all to know.

 

[KRS]

Re: Concrete mix in a bag.

I've done it the "dry" method and the "wet" method. I'm told there is enough ground moisture to set the "dry" method.

Both worked fine except the wet method is easier to dome.

KRS

 

[i386]

Re: Concrete mix in a bag.

I set a few posts for a short retaining wall. I thought the instructions were weird too, but I did it anyway. No problems.

 

[Bondo]

Re: Concrete mix in a bag.

Ayuh,...

If you just leave a bag of Concrete laying around the garage, It'll draw mosture from the air,+ get Hard....

In the ground,... It'll draw Plenty of water to harden....

 

[ThumbPkr]

Re: Concrete mix in a bag.

Using dry mix is the preferred method in some applications.Years ago,(back in the '70s) when AT&T started upgrading their infrastructure in anticipation of fiber optics their contractors used to buy from my redimix company when in the area.
Their specification was for dry product which we just dumped down the chute into their trench which would contain several runs of 4" PVC on the major arteries and they would be backfilling right behind the mixer.
I just picked up a bag of quickcrete from a freecycler and after carrying it down two flights of stairs and across the street to my pickup truck I was looking for something to cover the opened bag so it would not blow away on my return trip home.
I need not have worried,it was not going to blow anywhere.
What was worse is that he had not used very much of the bag either,it was almost full.
I chipped away at it after returning home and I think I can salvage enough of it to do what I wanted to do but I wished that I had been a little more inquisitive before I carried that heavy bag down those stairs.LOL.Ron G