concrete reinforcement

[flatout49]

ok i have pre existing building and im going to be grading down to in stall concrete what has people used or recomend to use as far as rebar weled wire or ive even been told to use bed springs lol. the shops going to have cars and truck and maybe a tractor on it not all at one time.

any info would be great thanks

new member jp

 

[ConCretin]

Welcome to GJ.

I'd stay away from the bed springs. Rebar or mesh are fine. Rebar doesn't sag as much between supports. If you use mesh, go with the sheets rather than the rolls.

I'd pay attention to your sub grade because it will do most of the work when it comes to supporting loads you place on the slab. The reinforcing is just there to hold any cracks or control joints together.

if in doubt, over excavate and install at least 8" of granular material and compact it well.

 

[dcs Inc]

Good info willys. Being a concrete contractor for 40 years I've seen all kinds of "stuff" thrown into slabs I've torn out and replaced. I'm not a big fan of the 6x6x10x10 rolls of remesh. Does nothing but make it a pain to remove. Rebar is really the way to go. 1/2" rebar grid 18" on center will give you a good, tough support system. As willys mentioned, it's as good as what you place it on. Compact the heck out of it, then compact it again. Keep a good look at the mix design. What depth are you pouring? Light traffic, a "true" 4 inches with plenty of crack control cuts. Saw cuts are great with an early entry saw cut saw. Have them placed no later than 12 hours after the pour. (If you wait much longer the cracks have already formed. Concrete cracks from the bottom up and when it shrinks, weak points form. If there isn't a weak point for it to form into, it will create it's own. Mix design is very important. I like straight bag mixes instead of fly ash additives to bring up the compressive strength. A 4000 psi is the same as a 6 bag mix. The difference is the 4000 psi mix is made with 5-5.5 bags of cement with fly ash verses 6 bags of cement. What's the difference you ask? One is the appearance, fly ash is a byproduct of burned coal. They reclaim it and found it strenghtens concrete mixes. Depending on the reclaimers and their cleaning efforts, sometimes it discolors concrete. When I was pouring a lot of concrete I prefered to use straight cement mixed concrete because of the yellowing fly ash caused, ( and a few other issues of creating surface cream for finishing.) Anyway, a 6 bag mix, 5" slump or less, no air entrainment, (I use crushed stone mix in Indiana instead of gravel)... depending on where you are located, ask your contractor which is best for longevity, and pop outs. If his first words are it's easyier to finish with a gravel mix, call a concrete ready mix company and as them. If you have questions on proper finishing techniques, let me know.

Oh, scotty, if you want to hijack this thread also to sell this guy some epoxy, at least add some pertinent information. here's that smiley thing

 

[flatout49]

thanks guys so a 18 by 18 square on center of 1/2 inch rebar is what i was looking for and another Q: the shop floor is 35x30 how many poors should i do it in 1 or 4 ?

 

[ConCretin]

thanks guys so a 18 by 18 square on center of 1/2 inch rebar is what i was looking for and another Q: the shop floor is 35x30 how many poors should i do it in 1 or 4 ?

Should be easily manageable in a single placement for a decent floor crew.

With regard to the bar, don't forget to locate it about mid slab on plastic or metal chairs. You can use cement bricks in a pinch but personally, I prefer the chairs.