Dry vs. Wet Pour Concrete For Pole Barn

[sschefer]

Re: Dry vs. Wet Pour Concrete For Pole Barn

The guy who told you that the concrete was superficial was correct, wet or dry, the concrete is only there to keep the poles straight until you get the roof on. With the poles set at 48" you'll break them before you move them once the roof is on.

He's the one I'd hire. Sounds like he knows what he's talking about and is not trying to rip you off.

 

[bucky7680]

Re: Dry vs. Wet Pour Concrete For Pole Barn

I've set thousands of posts in both wet and dry concrete. What most of you are missing is that the posts will break long before the dry concrete fails. Install labor is more costly and you have less time to make sure the posts are in line and plumb with wet concrete. There's more than the cost of a truck involved. The size and spacing of the posts and trusses has more impact on snow load that the type of concrete used. The OP did not say what area of the world he's from. In my local who cares about snow or frost. All care about is wind load


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If you are an ASABE member or if your employer has arranged for access to the full-text, click the underlined title below to view.



In-Situ Hydration of a Dry Concrete Mix
Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan www.asabe.org

Citation: Paper number 034003, 2003 ASAE Annual Meeting . @2003
Authors: David R Bohnhoff, Zachary D. Hartjes, David W. Kammel, Nathan P. Ryan
Keywords: Concrete, Cement, Cement hydration, In-situ hydration, Hydration, Concrete placement, Dry concrete mix, Concrete moisture content, Concrete testing

Hydration of a dry concrete mix after the mix has been covered with soil is herein referred to as in-situ hydration. In this study, a series of dry concrete mix footings were hydrated in-situ by burying them in sand and subjecting them to different water treatments. Footings were removed and cored at 4, 12 and 24 weeks. Compression tests on these cores showed that in-situ hydration could produce concrete with strength comparable to a normally hydrated mix. Additional research is needed to determine how in-situ hydrated concrete strength is affected by aggregate properties, initial compaction, confinement pressure, dry mix uniformity after placement, as well as conditions related to water movement into the confined mix.

 

[sschefer]

Re: Dry vs. Wet Pour Concrete For Pole Barn

I've set thousands of posts in both wet and dry concrete. What most of you are missing is that the posts will break long before the dry concrete fails. Install labor is more costly and you have less time to make sure the posts are in line and plumb with wet concrete. There's more than the cost of a truck involved. The size and spacing of the posts and trusses has more impact on snow load that the type of concrete used. The OP did not say what area of the world he's from. In my local who cares about snow or frost. All care about is wind load

I totally agree and the facts as you've shown prove it. If the compaction rate of the soil is 90% or better then you probably wouldn't need any at all. Wind, weather and curiious neighbors usually dictate the need for concrete unless you like rechecking the poles a million times. I think the side track here might me be people thinking the poles on a pole barn are similar to fence posts.

 

[avenger79]

Re: Dry vs. Wet Pour Concrete For Pole Barn

just a thought, if you've researched the contractors, narrowed it to 5, checked their references, and looked at buildings they've put up and liked them. why would you not let them dictate how the posts are set. It's the same as what they've done on other buildings you like correct?

why go to the pros if you don't want their expertise I guess is what I'm wondering.

 

[getinmerry]

Re: Dry vs. Wet Pour Concrete For Pole Barn

why go to the pros if you don't want their expertise I guess is what I'm wondering.

The answer is simple- Because the pros don't agree. Depending on who you're asking, you get different answers, and everyone thinks theirs is the right one. While shopping around, I was looking at structure (above ground) and talking to owners of the barns. I didn't realize that there would be a difference in concrete while I was doing my research. When crunch time came, and I started getting estimates, it became clear that this is a major sale point for the companies that use wet pour concrete. The companies that use dry don't mention that the posts will be dry-set. They only say "posts set at 48" with concrete". You have to ask about the pour method.

I'm very old-school when it comes to construction methods. I worked construction through high school and college. I learned lots of good stuff from the old-timers I worked with. These guys knew their stuff and had spent a lifetime working their crafts. Dry concrete mix has been around for many years- how come nobody ever thought of using it dry before 1995?

BTW- the companies that use dry-pour method only use standard pre-mix. They're not using the specially formulated mixed for dry pouring.

 

[wewefirex2x]

Re: Dry vs. Wet Pour Concrete For Pole Barn

Sturdav,

Synthetic fibers DO NOT add strength. There intended purpose is plastic shrinkage cracks (cat hair fiber). The larger polypropelene fiber is intended to be used instead of wire mesh. Not contradicting anyone just telling the facts. They have been known to add strength ONLY because the fibers hold the cylinders together in a compressive strenght machine.
If your contractor insists on a dry pour, then talk to them about ordering your concrete from the batch plant with a minimum amount of water mixed in it, when it arrives at the job site add just enough water to get it down the shoot and into the post hole.

For others,

I also agree is the planning is done correctly a Batch Plant Wet concrete is best. You get all of todays admixes in liquid form and properly mixed and dosed at the plant. If the truck can drive along the Pole Bases you would be able to do all holes in no time. Make sure they consolidate material with vibrator to avoid air voids....

 

[v1_0]

Re: Dry vs. Wet Pour Concrete For Pole Barn

Very interesting set of comments. I have one manifesto to add..

I'm going to talk about "sufficiency". Put plainly: it's the policy of "good enough".

I think at a gut level we all have a grasp of what this means. What you may not realize is that this happens to be one of the major drivers of a lot of what goes on in the business world. (I can only speak from experience on what goes on in the software business world, but I can read the signs of what I see elsewhere and they match).

It is not necessarily a bad thing.

Since we are talking about a pole-shed here, and specifically about the post set into the ground, let me use that to illustrate.

Now, these numbers are purely fictional so don't dwell on them, but do consider the process that they illustrate.

Lets say that if we just buried the post in the ground (no concrete) and compacted the dirt around it we'd get a 'holding force' of 100. The effort to do this is 30 (dig soil back, compact).

Using the dry pour method we get a holding force of 200, and the effort to do this is 15 (pour cement in, a little soil on top, and a little compaction).

Using the wet pour method we get a holding force of 225, and the effort to do this is 30 (mix cement, pour cement, "burp cement", throw a little soil on top).

Clearly, the wet pour method provides a better holding force than the other methods. However, when we look at the total picture - benefits (holding) -vs- cost (effort), then things aren't so cut and dried.

The dry pour method has 25 less holding force BUT costs 15 less in effort. The question becomes: is a holding force of 200 sufficient? ("good enough"). If we are talking about the difference between withstanding a 100 MPH wind -vs- a 90 MPH wind, then yeah, looks like it would be. However, if its more like 100 vs 30 MPH, then no - not sufficient. The law of diminishing returns comes in here: at some point the cost for extra quality exceeds the benefits you get from it.

Finding the 'sweet spot' on this equasion is the tricky thing. As consumers, we run into this thing all the time - I'm sure you have had the experience of calling into some service center (bank, credit card, boat supply store), and have noticed that some respond quicker than others. Somewhere in that business someone made a staffing decision. It was probably based on cost of the staff, and how many (average) calls per hour they receive, and how long an average phone call lasts. (Hopefully for that particular hour of the day: this analysis can be very detailed - hour, type of call, number of each type, time to service each type, or it can be simple: number of calls per day, average time per call.) AND it was based on response time: was 5 minutes to answer the phone OK, 10 minutes, 15 minutes? What is sufficient so that we don't loose more than a few customers?

It's that decision that pretty much determines how long you are going to be on hold. "Please stay on the line. Your phone call is important to us. Just not important enough for us to hire enough people to respond to it quickly."

You may remember that I did say that this is not necissarily bad, but what benefit does a consumer get from this? Well, staffing costs money. That money comes from somewhere - yeah, us. So, instead of paying only 18% on your credit card (or getting an interest rate of 1.33 on your savings) you would pay 20% (or get an interest rate of 1.25). [Hopefully no one pays that much on their cards! Go to bankrate.com and find a better one!]

-V

 

[v1_0]

Re: Dry vs. Wet Pour Concrete For Pole Barn

Sturdav,

Synthetic fibers DO NOT add strength.

Fibers add torsional (twisting) strength but not compressional (standing on) strength.

 

[sschefer]

Re: Dry vs. Wet Pour Concrete For Pole Barn

You forgot one thing. The poles are set 48" into the ground and they are top loaded. Strength/Shear is dependent upon the pole itself and not how it's set.

There's little to gain structurally by pouring concrete, wet or dry. It will hold the poles straignt and if that is the purpose then a bag of quickset and a little water (dry pour) is all you need.

 

[sturdavj]

Re: Dry vs. Wet Pour Concrete For Pole Barn

Sturdav,

Synthetic fibers DO NOT add strength. There intended purpose is plastic shrinkage cracks (cat hair fiber). The larger polypropelene fiber is intended to be used instead of wire mesh.


OK' Next question what dose sand add to cement ?

 

[Nandy]

Re: Dry vs. Wet Pour Concrete For Pole Barn

You have been looking in all the wrong places. Find you an "old school" contractor...
You spent an awful long time researching this to find the best companies that seem to do this locally. Let them do it their way or find you an old school contractor.

 

[sschefer]

Re: Dry vs. Wet Pour Concrete For Pole Barn

Sturdav,

Synthetic fibers DO NOT add strength. There intended purpose is plastic shrinkage cracks (cat hair fiber). The larger polypropelene fiber is intended to be used instead of wire mesh.


OK' Next question what dose sand add to cement ?

Sand doesn't add anything to cement. Portland cement is the binder. If you mix sand or gravel with cement you get a much stronger bonded product thats often called concrete.

 

[sturdavj]

Re: Dry vs. Wet Pour Concrete For Pole Barn

Would synthetic fibers when added to cement not work much the same way as sand & aggregate, creating even yet a stronger bond in the concrete mix? Agreeing the primary purpose is to prevent cracking and separating of the concrete.

 

[bandit86]

Re: Dry vs. Wet Pour Concrete For Pole Barn

I thought local utility companies set their hydropoles in sand only

if it keeps a hydropole straight, might be a way to go

I've heard a lot of guys around here sticking fenceposts in sand only as well, and having it stay straight just as long

probably completely unrevelant to the building of a pole barn

 

[v1_0]

Re: Dry vs. Wet Pour Concrete For Pole Barn

Would synthetic fibers when added to cement not work much the same way as sand & aggregate, creating even yet a stronger bond in the concrete mix? Agreeing the primary purpose is to prevent cracking and separating of the concrete.

http://ace-mrl.engin.umich.edu/NewFiles/publications/Nelson2002.pdf

 

[Off-Peak]

Re: Dry vs. Wet Pour Concrete For Pole Barn

funny to see this thread today.... Dont bother sending flames my way because I prob wont be back over to this thread...

today i mixed (6) 80lb bags... Yeah, wet is better, MUCH BETTER. Trust me, I had to work to get the dry pockets wet as I mixed (1) bag at a time. I doubt the project is in danger, but hands down, the best mix is the one that is MIXED.

Gotta go.... I'm going to bake a cake without mixing the mix. Add the eggs and toss in the powder and off to cure in the oven...!!

 

[SuzukiChopper]

Re: Dry vs. Wet Pour Concrete For Pole Barn

I wasn't going to add my 1/2 cent to this thread because I don't know cement. However I think the K.I.S.S rule applies to this situation, and I'm not just talking with the construction of the barn. I'm talking more along the lines of thought process of who to use to build it.

This all reminds me of getting quotes to build a brick patio. Old school landscapers want to do a layer of crusher, then 2" of sand and then brick. Some of them want to do 1/4" crushed, crusher dust and 1" of sand. Some just want to do 1" of sand. Prices change quite a bit with each method of course. Just 1" of sand would have normally made it an automatic NO for me, but found out the company spends enough time compacting the earth and compacting the sand it's a non issue.

Being old school isn't a bad thing, but keep in mind that a LOT of new information, techniques and processes have been developed and learned since the days of yesteryear. What may not have seemed proper then, may be absolutely acceptable now because someone figured it out 15 years ago and has proven it to be viable. Like was mentioned, dry mix just didn't come out in 1995, but maybe someone in 1980 was using it and it took 15 years to be proven as a sound construction technique with the right process.

No you would never use dry mix for foundation walls, a footing or a slab... but to support a pole buried 48" in the ground, using dry mix does sound reasonable. The rest of the barn construction and the techniques they use should be evaluated though because that is the part that is going to provide the support. Maybe some of these guys trench the earth so they can provide extra support with joists buried in the ground?

 

[Bass Man Bruce]

Re: Dry vs. Wet Pour Concrete For Pole Barn

Well here is my 2cents.
The only purpose of the concrete pad is to spread the vertical dead and live load at each pole over enough area of the ground to prevent compaction of the soil and thus movement.
The pads are footings nothing more or less. No concrete vendor I've heard of would ever guarantee their product without a premix with water.
That said, yes a lot of builders do the dry mix thing and it works most of the time.

As for snow loads I've done post mortem inspections (I am a building inspector) on numerous pole barn roof failures and every one was due to a lack of "bottom chord and lateral web bracing".

Simply put these are 2" x 4's that run perpendicular to and are fastened to each of the trusses at precise locations determined by the truss manufacturer. They are installed during construction of the building not the trusses.
The lumberyard should give you the info on this when you receive the trusses.
Good luck!

 

[WizeOne]

Re: Dry vs. Wet Pour Concrete For Pole Barn

I've pried many a 4 x 4 fence post root out of the ground that was set with dry concrete mix. You couldn't convince me that the drymix does not absorb sufficient moisture to harden up.

Heck, just leave an unopened bag of redimix on the floor of your garage for a year, then go back and try to pour it. And that bag was never even in the ground, having received a soaking like it would be for your barn supports.

 

[Tim Frank]

Re: Dry vs. Wet Pour Concrete For Pole Barn

Well here is my 2cents.
The only purpose of the concrete pad is to spread the vertical dead and live load at each pole over enough area of the ground to prevent compaction of the soil and thus movement.
The pads are footings nothing more or less. No concrete vendor I've heard of would ever guarantee their product without a premix with water.

I don't know why "concrete pads" and "footings" entered the thread discussion and I don't recall anyone suggested a dry mix could be used for that purpose.
Pouring any type of concrete around a post in a hole, to set it, does not really constitute a footing or pad.

The question asked by the OP was whether he was being overcautious about the choice of setting posts in dry vs wet pour concrete.

We've had responses touting the dry mix as fine, ...the wet mix as much better or the only way to go, ....and some who suggest that it really doesn't matter as the posts aren't going anywhere laterally (unless they shear at ground level); one person pointed out that well compacted gravel might be the best solution since concrete (either option) is prone to promoting post-rot.

I'm increasingly coming to the opinion that there hasn't been a "wrong" answer so far.