pole barn concrete slab

[buckeyefarmer]

Instead of continuing to hijack another thread, I'll start my own. I'm getting prices for a 30x48' pour in my pole barn. Got 2 prices, getting a 3rd. One guy said to box around the poles about 18" away, to not pour the concrete against the poles, and then fill this later with grout. This is to keep movement of the poles away from the slab to prevent cracks. I had not heard of this, nor have I seen this in any pole barn that I have been in with a concrete floor. does anyone have theirs done this way? He's also recommending a one bag fiber mix, 4000psi instead of rebar, but has no problem doing rebar if I want. Adding the fiber will be about half the price of the rebar cost, saving a couple hundred.

 

[SPIKER]

I'm planning on a wrap of styrofoam board material around my posts thick enough to still let the wood expand & contract later grout might be put on top to seal out any ants that may show up is all...

Mark

 

[dcyrilc]

Instead of continuing to hijack another thread, I'll start my own. I'm getting prices for a 30x48' pour in my pole barn. Got 2 prices, getting a 3rd. One guy said to box around the poles about 18" away, to not pour the concrete against the poles, and then fill this later with grout. This is to keep movement of the poles away from the slab to prevent cracks. I had not heard of this, nor have I seen this in any pole barn that I have been in with a concrete floor. does anyone have theirs done this way? He's also recommending a one bag fiber mix, 4000psi instead of rebar, but has no problem doing rebar if I want. Adding the fiber will be about half the price of the rebar cost, saving a couple hundred.

We have three pole barns. 24x60, 24x72, and one 30x36. Poared right against the posts and have had no cracking in 20 years. 6" slab on each building. I have talked to engineers about fiber in the concrete and have been told that it is an exceptable substitute for 1/2" rebar. The only drawback I know of is if you want a burnt finish on the floor, you can't do it with the fiber.

 

[crbr]

Instead of continuing to hijack another thread, I'll start my own. I'm getting prices for a 30x48' pour in my pole barn. Got 2 prices, getting a 3rd. One guy said to box around the poles about 18" away, to not pour the concrete against the poles, and then fill this later with grout. This is to keep movement of the poles away from the slab to prevent cracks. I had not heard of this, nor have I seen this in any pole barn that I have been in with a concrete floor. does anyone have theirs done this way? He's also recommending a one bag fiber mix, 4000psi instead of rebar, but has no problem doing rebar if I want. Adding the fiber will be about half the price of the rebar cost, saving a couple hundred.

Fiber admixture is not a primary reinforcement product. It will not prevent nor reinforce anything about or in concrete, except surface shrinkage cracking. Whoever is telling you otherwise does not know what they are talking about. Not to brag but I have a MS in Concrete Technology and have done more research than should be allowed. Fiber is not a reinforcement substitute. However I would not place concrete without it. It's cheap and does serve a purpose for the surface (only).

Use rebar. If not, don't say you wish you'd have used it, later on.

Concrete away from the pole does not prevent cracking. It will seperate the slab from the pole, leaving it as a floating slab. Use rebar and expansion joints.

Concrete will crack. You can choose to control it to crack where you want it to or it will crack at random. Your choice but you only get to make the choice once.

Do not allow the rebar to lay on the ground. Use chairs to raise it to the proper height within the placement. They are very cheap for the return on the investment.

Use 4000# regardless. Do it right and don't squabble over a few hundred dollars.

 

[dodge85rc]

Mine is poured right next to the posts and I don't have any cracking, at least not because of the posts shifting. Make sure they cut enough joints into it! The guy who did mine didn't cut any, but put two plastic strips in the concrete to create 3, 18x30 sections because he didn't see a need to cut it. Needless to say, up in the north, it cracked all over the place the first winter. I am still pretty ticked about that and its been 6 years. I had my brother in law try to cut a few more joints in it and that seemed to keep the cracking at bay. If I didn't have so much crap in the shed and concrete wasn't so expensive, I would rip it out and do it over, a section at a time.

 

[crbr]

Cutting is done after stress starts to build in the placement and I am sure no one on a slab will do post-stress relief. Cracking has already begun and has nowhere to go (controlled) until the joints are cut. After 24 - 48 hours, it's of no real benefit but will work to a degree. These are symptoms of the such. Put the joints in prior to the placement curing beyond the finishing. Take the time to do it correctly.

Also use an air entrainment mixture for the freeze-thaw cycles. The southern tier region actually gets more freeze-thaw cycles than the north. I'd ask for air entrainment regardless.

Plastic strips are useless.

 

[drhomer32]

Putting foam around the perimeter of building and posts will will give you expansion room. I would also suggest that you have expansion joints cut off of the posts as well. As far as the rebar you need to pour a #3 (3/8") rebar on 2' centers on compacted base...also make sure that the steel is put on rebar chairs this give a constant for location of steel. ALSO...maybe most important...make sure that the grade under the pour is not up/down (unlevel)...it will make thin and thick spots which is something that will cause cracking than anything else.

Good Luck!!!!

PS- nothing wrong with a 4000 mix but a 3500 is good for most applications!

 

[buckeyefarmer]

I had never seen a gap at the posts, which is why I asked. He was planning on a keyway in the middle of the 48' length, then cut the middle of the 30', so I'd have 4 squares 15x24.
this guy also mentioned non air entrained concrete. I used air entrained on my garage floor when I did it years ago. It's 24x30, no cuts, and it did crack a little. It has rebar, which I placed.

of 3 quotes, 2 want to do the prep, the third wants me to have the prep done beforehand. I'm pretty sure I will go with the rebar. I can get it for $.29 ft or 5.80 a stick (last time I bought it it was $.16 ft)

thanks for the comments.

 

[crbr]

I had never seen a gap at the posts, which is why I asked. He was planning on a keyway in the middle of the 48' length, then cut the middle of the 30', so I'd have 4 squares 15x24.
this guy also mentioned non air entrained concrete. I used air entrained on my garage floor when I did it years ago. It's 24x30, no cuts, and it did crack a little. It has rebar, which I placed.

of 3 quotes, 2 want to do the prep, the third wants me to have the prep done beforehand. I'm pretty sure I will go with the rebar. I can get it for $.29 ft or 5.80 a stick (last time I bought it it was $.16 ft)

thanks for the comments.

Joints are to your choice at this point. I'd place one more within the 15x24 and then fill in the joints with self-leveling filler. That (15 x 24) is still a good size area for the opportunity of cracking. I have seen a lot of placements like this while working in the construction of nuclear power plants (very design regulated). Section your areas at 15 x 12 with one extra area joint. Just my opinion.

Air entrainment allows for small air pockets within the placement to allow for water expansion when it freezes. It's inexpensive and I'd suggest it regardless.

Good luck on the placement and have fun.

 

[Diamondpilot]

None of the barns around here have the space you talk of. All are poured right upto and around the poles. I had joints put every 10' in mine and no cracking.

Go 4000psi 6 bag mix with fiber and 6" and you will have no issues if the prep and base are done right.

Chris