new concrete driveway rebar or??

jake00 · Nov 22, 2009

I'm going to get a new driveway quoted out

roughly 5" x 20' x 40'

Is rebar supposed to be used, or are there "new and advanced" materials out there?

JD in DFW · Nov 22, 2009

Yes to the rebar, if it's asddition to a current drive the rebar will need to be tied into the exsisting driveway slab.

wakeboarder311 · Nov 22, 2009

wire mesh is fine

ScaldedDog · Nov 22, 2009

JD in DFW said:
Yes to the rebar, if it's asddition to a current drive the rebar will need to be tied into the exsisting driveway slab.

x2 on the rebar. However, why is it necessary to tie the new slab to the old? Every one I've ever seen done this way ended up cracking one slab or the other at the rebar.

Mark

jake00 · Nov 22, 2009

the old one is going to get replaced

MN BIANCHI · Nov 22, 2009

I just finished pouring 117 yards. We used 1/2" rebar running both directions 2 ft on center.

ddawg16 · Nov 22, 2009

This is just my opinion.....

Wire mesh is fine for non-heavy loads, such as a walkway.....but when a car is going to be driven on it....#4 rebar.

If you look at driveways that have heavy cracks from veh traffic...they are usally the ones that only had rebar.

It's also interesting to see how thickness standards have changed over the years....20-30 years ago, 3 1/2" was fine....now they want 4" min.

Truth is, the additional cost of another 1/2" of concrete is nothing compared to all the work you have to put in to the whole project....

Schrodingers Cat · Nov 22, 2009

MN BIANCHI said:
I just finished pouring 117 yards. We used 1/2" rebar running both directions 2 ft on center.

117 cu yd? at 6" thick that is ~6400 sq ft...
that is way over kill...#4 on 2' center, both directions
with a 4" slab you barely have enough cover for the rebar...

for a slab on grade, if the subsurface is prepared correctly (compacted, level, and some stone) the slab is under compression...the best scenario for concrete

even if it is only 3000 psi mix, the maximum pressure it will see is ~tire pressure...< 50 psi for a residential driveway...

the new fiber mix stuff is good for this application, or just some 'chicken wire'

idunnosh#t · Nov 22, 2009

I agree #4 bar on 2' centers,4000lb over compacted aggregate base.Don't go with any bid until u checkout references and some previous work. Have them include soft cutting in the bid.Personal preference but I prefer more cuts than more cracks .I always use expansion mat. backer rod and Slp. My.02s

MN BIANCHI · Nov 22, 2009

Schrodingers Cat said:
117 cu yd? at 6" thick that is ~6400 sq ft...
that is way over kill...#4 on 2' center, both directions
with a 4" slab you barely have enough cover for the rebar...
'

The pour was for a new building 48' x 104' with a apron of appox 19' x 104'. In addition we poured over 1000 sq ft of driveway. The pour was 4 inches of 4000 PSI concreate plus select areas with thicker edges. There was a minimum of 4" of compacted class 5 under the slab. The indoor portions were insulated with 2" high density poly foam board insulation. The driveway and slabs do have traffic heavier than a standard automobile.

twostory · Nov 23, 2009

I just had a driveway poured. I used #4 rebar, 2ft OC. 4000 psi concrete, 5 inches thick.

I had a few contractor tell me that was overkill, but I do drive an RV on this driveway, and a small dump truck once in a while.

The contractors who complained, did not get the job.

I asked them directly, "How much more labor is 5 inches, vs 4 inch?" Uh none really was the answer. I then told them, I paying for the material, so give me a quote for the job, the way I want it done.

I found a guy I liked, he answered all my questions correctly and suggested a few things that made sense. I called the concrete company where he has an account. They told me he pays on time every month. I inspected a job he did a month earlier, it looked good.

He got the job, I like my job and all is well. Funny thing is another "garage journal" member called my guy and could not get him to quote his job? I guess he was busy? (don't know)

All this proves is get a good guy, and if his schedule is not busy, you will probably get good results.

BRENT in 10-uh-C · Nov 26, 2009

Does the type of soil under the concrete matter? I would think you could get away with less steel if you were pouring on compacted clay vs. sandy-type soil.

'Bianchi', was that 4000 psi concrete the fiberglass reinforced kind?

brownbagg · Nov 26, 2009

rebar is for load factor, if you have good compaction then the average car will not have enough weight to bend the concrete. Concrete cracks when it bend by load. The act of rebar counteract the bending so more load can be applied than plain concrete can hold.

If you had a driveway that held only cars then nbo rebar is not needed. But it doent hurt anything to be in there. By adding rebar you are improving the product. So if you can afford the extra money for the steel, by all mean have it installed.

Just remember the extra steel might need extra coverage of concrete. A #4 bar is 1/2 inch thick, by having two bar cross that a total of one inch. You need 2 to 21/2 inches under the bar and at leat a inch on top so that 4 1/2 inches. if you use #5 that 5/8 thick.

If I had plenty of money I would do #5 6 inch thick.

idunnosh#t · Nov 26, 2009

Do yourself a favor and don't skimp on the re-bar.Mother Nature and Father time are your concretes biggest enemy's.Concrete is constantly expanding and contracting with variations in temp, sunlight,rain water infiltration,ground moisture etc. Your in a region of hard freezes and open concrete lets the frost drive it'self deeeeep! All the compaction in the world will not keep that slab from frost movement.Re-bar makes the whole slab monolithic, with out it each section of concrete is independent of the next and will be subject to individual loading factors(movement). THE LAST THING YOU WANT IS HEAVED CONCRETE!Re-bar is crucial,cheap insurance.,Don't trust any contractor that tells you otherwise!!34 years in the Trades B.T.W Concrete initially cracks from contraction as the water cures out.that's why soft cutting is better I.M.O.

new concrete driveway rebar or??

jake00

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JD in DFW

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wakeboarder311

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ScaldedDog

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jake00

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MN BIANCHI

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ddawg16

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Schrodingers Cat

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idunnosh#t

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MN BIANCHI

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twostory

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BRENT in 10-uh-C

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brownbagg

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idunnosh#t

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