concrete floor cold joints?

[roaddog359]

I am talking with several concrete people for my 36 x 48 heated and insulated pole barn project and i have heard everything and I am confused. One says wire is a unnecessary expense and will pour all at one time with a rat wall. another wants to pour in sections and use cold joints with rebar connecting the slabs with 2" foam then visqueen then foil bubble wrap. with a rat wall and foam on the inside floor around the perimeter in the rat wall. another will make one pour 5" with wire and fiber no rat wall or foam and only visqueen. what is the best way to pour this slab? I want 5" with fiber, 6 bag mix, and at least visqueen, foam is a plus. What about a rat wall and the foam or foil wrap? is wire necessary? is it better to use cold joints or should the pour be all at one time? HELP!!! I am running out of time. Thanks

 

[trbomax]

I would like a fairly deep (18") ratwall with 2" foam around it.The 5" slab is OK with 6bag and fiber,you wont gain anything by haveing fiber and wire together.All one pour with sawed joints the next day,cure and seal on it as soon as you can walk on it and not leave marks. I rolled 1 coat on right away,waited 3 hrs or so, and gave it another.I would and did , make bowls where you want a hoist or crane columbes,although in my old shop I did not and nothing cracked or broke in 20yrs.I laid a pattern of 5/8 rebar where the hoist goes to,but only because I had it laying around.Plastic under is a must,but I personally wouldnt want foam if I was loading the floor heavy,which I do. Our groomer tractors are 26000# and I have no cracks yet doing it this way.

 

[kmacht]

I,you wont gain anything by haveing fiber and wire together..

Not true. I just went through this same debate on a concrete pour for my garage. I did quite a bit of research on rebar / wire / fibers. The fibers are going to help with shrinkage cracking, surface cracking, spalling, etc. The basicly help the concrete stick to itself better. The wire or rebar is there to help with the load but more importantly it is there in case you have any settlement cracking. If your sub base isn't perfectly compacted or settles/errodes over time and the slab cracks your wire or rebar will help to hold to two pieces of concrete together and keep the crack from getting bigger and bigger. Once it cracks the fibers in the mix do nothing for you. If you can afford it then go with rebar on 2' spacing (squares) and fibers. If that is too much then eliminate the fibers and go with just the rebar. If that is still too much then consider both wire mesh and rebar.

The insulation and vapor barrier all depends on how you plan on heating. If you are doing in-floor heating then the foam and vapor barrier is a must. If you won't have a heated floor then leave the foam out. The vapor barrier issue is still open for debate. It works well if done right but can also cause surface cracking and spalling if the mix is a litte too wet and poured incorrectly. With a vapor barrier the concrete can only cure from the top down. All the excess water in the concrete now has to go up because it can't escape through the bottom. Just make sure you have the appropriate slump when pouring as it is more critical with a vapor barrier than not.

Keith

 

[trbomax]

Well,please dont take this wrong,but my engineering data came from my brotherinlaw,who worked for MDOT testing concrete samples used in highway projects. They test every batch and do a lot of research also.He's retired now,but is a wealth of info about pavement material,thats all he did.

 

[red]

With the plastic vapor barrier some masons are using 1" to 2" of sand on top of the plastic to aid in curing. Helps with allowing water to drain into the sand. After my slap was poured I covered it that night with plastic and kept it soaking wet for over two weeks. Used 1/2" rebar on 2ft centers with mesh tied on top. No fiber and only a few very fine hair line cracks that are visible when wet. This was on 26X32 slab with 4' to 6' of clay/sand fill. Used water compaction no mechanical. -Ed