pouring concrete dry

[okclumberjack]

I know there are going too be some comments because i always here you can't pour dry concrete for fence poles but my 2.5 acres has a 6 ft fence around it coming on 15 years know & is solid as a rock, anyway what i'am getting @ is, i want to pour a retaing wall 4 inch thick with rebar & about 25 ft long & probally 3 ft tall & was considering pouring it dry & was wondering if anyone has any experience with this i want to put a car port next to my shop with gravel base to park a boat but it slopes away & will need to raise the outer side up 3 ft to make a leval pad, will frame up & pour H20 as i fill & probally keep a sprinkler on the forms to keep wet for a couple of days any exp. doing this???

 

[stuckmotor]

We'll see what the experts say but, I'm afraid, if you don't mix the concrete it'll end up with dry pockers that don't stick and will weaken the whole pour. I'll be plesantly surprized if I'm wrong.

 

[Egon]

At one time you could get no slump concrete. What's available today I don't know.

Check with the local concrete supplier for what they have available is the easiest way.

 

[vtsnowedin]

:duh:
A lot of fence posts get backfilled with just dirt so even a poor concrete job is an improvement. Your letting the soils moisture provide the mixing water and there is usually enough to get the job done as all the sides of the hole your dry mix comes in contact with are moist.
A retaining wall on the other hand should be poured in a form front and back and would be completely dry and there is no way water added to the top would get properly mixed with the cement powder and give a decent job. Mix your crete in a wheel barrow or rented mixer and have a uniform product that will bond to your rebar and do a good job that lasts for years or just have a truck deliver it if your wall is anyway near a road. A tractor FEL does a good job of transporting crete from the truck down through the woods to your wall if your off road but they do charge for waiting time.

 

[Pipestone Kid]

what vtsnowedin said!!!!!!

 

[Brad_Blazer]

If you compare prices you may find that having a truck come is less expensive than buying pre-mixed bags. Around here I can only come close by buying bulk aggregate and portland cement. Form up your wall and when the truck comes the pour will be quick and easy.

My new method of putting in landscape timber fence posts is use a 4" auger and pour dry sand around the post, wiggling the post and maintaining plumb as the sand is poured. Sure beats tamping for line posts. Most large flag poles are in a metal sleeve filled with sand.

 

[FredH]

Don't know if cheaper , but once done , the wall looks a heck of a lot better than cinder block or plain concrete wall .

8 in. x 12 in. Red Charcoal Concrete Garden Wall Block-M0404COTA181 at The Home Depot

I currently have 3 walls with the highest being 3+ feet tall and have drove my TC 30 New Holland along the edge without any movement of wall . I purchased mine at a local Masonry / brick / rock supplier . They actually make them on site so they are a little cheaper than big box stores . The link I posted is similar to what I used , but mine weigh in at 67 lbs. a piece . First layer Sucks . Pick up and lay down each block several times till it is level and pitched , but after that it goes pretty quickly , at least as long as your body holds up .:thumbsup:

Fred H.

 

[/pine]

To poor a reinforced wall you really need to vibrate the pour even if it is by just using a hammer on the outsides of the forms...and the concrete needs to be wet enough to encapsulate the reinforcing...if you do not do this you will end up with severe "honeycombing" and a very weak wall...

 

[EddieWalker]

No, you cannot do a dry mix for a retaining wall or anything else and expect it to have any strength. A big part of what gives concrete it's strength is the water activating the cement in the mixture. Sand, Gravel and Cement with water will give you concrete. You can vary the strength of it by how much water and how much Cement is added to the mix. By eliminating the water in the proper amount, you eliminate it's ability to bond together.

Fence posts are different, what you are doing there is wedging, or locking the post in the hole. The concrete will set up, but the amount of strength you get is greatly reduced when done dry. Some fence builders who do this commercially will never use a dry mix because of need for all the strength they can get out of the concrete. For most residential fences, a dry mix, or just compacting the clay around the post is good enough.

Eddie

 

[Carl_NH]

Not relevant to the question on concrete but another good retaining wall option is used railroad ties. 5 ties high is about 40" and if you bury the first one on a base of stone you get to 36" total.

For your height and length you would need about 18-20 RR ties with dead men (2-3' section of RR tie ran perpendicular to the wall into the banking). Cost with spikes and ties $200-250 range.

 

[jerrybob]

Good comments above......you don't want to dry pour unless the boat you are covering is no longer wanted and you have good insurance on it!

 

[etcallhome]

I agree with the others about the retaining wall. but as for the fence post ??? Around here if using pressure treated post for buildings and then just for post Sakrete is saying do not put concrete around a post .. Reason once the concrete sets up it will stay one size, right , well the wooden post is wet ,or has moisture content ,it dries out shrinks, then leaves moisture come in crack between edge of concrete and the wooden post . will cause your post to rot out quicker.
Older brother was told this by a Sakrete rep last fall.

 

[LD1]

I agree with about everything said.

At 25' long, 3' high, and 4" thick, you need 25 cu ft of concrete. Thats 50 bags, and about $150-$200 worth of cement. And will all be wasted if you dont mix it. And a TON of work if you do.

Most concrete outfits have a $300 or so minimum. Well worth the extra money. You may not think so now, but if you opt to hand mix, you will agree with me long before you get 50 bags mixed.

I also agree that there are better ways of doing a retaining wall. I like the stackable blocks personally. Best looking, and much easier.The 12" wide and 5-1/2" high blocks are only $2 each. 6 rows (about 33") for 25' is only 150 block. And will look a whole ton better than a plain concrete wall.

 

[Short Game]

As far as fence posts go, I live where they can hardly dry out. I never set any post in concrete, unless I want to make it so heavy that someone would not want to pull it out by hand and steal it.

A local farmer's kid taught me fence post science. It's all in the tamping. I tamp it, and tamp it hard, every couple of inches of dirt, starting right at the bottom, all the way to the top. I bless that kid every time I set any kind of post in a hole.

 

[/pine]

In my experience just gravel works as good as concrete mix for stetting posts...unless it is a gate post where any stress or strain is not static...IMO setting them in wet mixed concrete is a waste of time and effort...

 

[quicksandfarmer]

Some people build retaining walls from unopened bags:
http://www.tractorbynet.com/forums/photos/95343-retaining-wall-unopened-sacks-concrete.html

 

[whistlepig]

I wouldn't hang a gate on a post that wasn't set in concrete. And I sure wouldn't give a good tug with the tractor stretching a fence against corner brace posts that weren't set in concrete. Concrete may rot the posts out. Some of mine have been in the ground over twenty years now with out rotting.

 

[okclumberjack]

I like the post that quicksandfarmer posted from bird , stacked bags with rebar might be what i do , but i still think it's the same concept as pouring into a form dry, keep it wet for a few days the take your forms apart & have a solid wall i have pulled fence poles out that were poured dry & there isn't any soft crumbly concrete attached to that fence pole it's solid as a granite rock.

 

[bcp]

Build a small test section of form and try it with several bags.

Maybe we will all be surprised.

Bruce

 

[Drexel]

If you compare prices you may find that having a truck come is less expensive than buying pre-mixed bags.

I mixed approximately 133 80# bags of concrete for my pole barn thinking that mixing it myself would be cheaper then having a concrete truck deliver.
Six months later, while building a new home I needed about the same amount of concrete to support a 16x24 ft. deck. Because of the size of the concrete pillers I was afraid I wouldn't be able to mix the concrete fast enough to keep part of it from drying before I was finished so I hired a truck to deliver the concrete.
Even with the extra charge for ordering under a certain amount of concrete I still came out cheaper then if I'd mixed it myself. Oh well, you know what they say about assume.