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Pouring a new driveway

Posted by cin_ram1972 (My Page) on
Thu, Oct 7, 10 at 22:16

Hello everyone, first time poster. I'm ready to sign a contract for a new driveway, but I'm on the fence on the use of fiber mesh reinforced concrete without any rebar or wire mesh for a driveway.

I live in South East Wisconsin so during the winter months we deal with many thaw/freeze cycles and most of the soil around here is clay. I don't plan to drive anything heavier than 10,000 lbs on it(work truck)

I have 4 quotes, 3 use wire mesh and 1 uses fiber mesh reinforced concrete, but no steel reinforcement. All pour 5 inch, 6 bag low chert. The ones using wire mesh cost almost $2500 more.

My research has found that fiber mesh reinforced concrete has come a long way, and that when poured without steel reinforcement, the cracking is minimal or the same when steel is used.

Any opinions would be greatly welcomed
Thanks.

C R


Follow-Up Postings:

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RE: Pouring a new driveway

Cin,

I'll admit I've never done a driveway using the stuff so I don't know the impact. I am familiar with the characteristics of fiberglass and also familiar with the characteristics of steel reinforcement.

Clay is just about the worst subsoil for laying concrete onto especially if the ground is prone to be damp. No matter what is used, if the base is not properly prepared, you'll have an ugly driveway in a few years. But if it is prepared properly (deep packed base) and properly applied stress joints, you can end up with a pretty good surface that lasts a long time. In your climate and considering the soil, I suggest you go with the strongest reinforcement possible. Fiberglass reinforced concrete has it's uses but I question it's credibility for your situation. I'm very familiar with fiberglass fibers being mixed throughout the concrete to make it lighter and it appears to be stronger. I'm not familiar with fiberglass mats being used alone for reinforcement. I know if you put down steel reinforcement, you can throw plywood over it and drive on it without much damage to the grid. I'm sure suspended fiberglass will not do the same. Concrete generates a lot of heat while curing. I wonder what effect that will have on the integrity of the fiberglass grid. Also, I wonder how the stress joints will react in your brutal winter.

Since all the contractors you've had out most likely have done similar work before, ask them to give you some locations where they did the work over a year ago so you can look at them. Once the driveway is down, it's too late for second thoughts. Give your state or county road engineers a call or maybe an email and ask them what their take is on it. I'm sure they have experience with both. My final thought is if it were that good as well as it is cheap, most all of the contractors would be using it. They surely wouldn't be hauling all that steel around if they didn't have to. They want to get in, get the job done and get out as quickly as possible so they can get their money and move on. Most credible people who do that kind of work treat it as a work of art, they are proud of it and want to see it last and brag about it when it does.

Good luck with your project. Could you do me a favor and let me know what you finally chose and why? I'd like to know more about it especially if you go with the fiberglass.


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RE: Pouring a new driveway

Maryland,
I really appreciate your input. I will most certainly let you know what I decide.

The fiber material that is being used in the concrete by this one contractor is called "fibermesh". It is manufactured by one company and from what I have just learned it is a combination of synthetic fibers.

And talk about irony, you stated that I should contact a city engineer. It was an acquaintance that works for a survey and engineering firm that recommended this contractor who uses "fibermesh" Although at the time he made the referral there was no mention about the mason using "fibermesh" only that he had done a big job for one of their projects and it was a great job.

The general consensus seems that the sub-base is the most important part to any flat concrete work. I've also just learned that fibermesh is nothing new, it has been around for a long time. But for what ever reason it is not mentioned much around residential projects

I do have to add this:
When I spoke with the 3 masons that use wire mesh I got the impression that they were old school guys, which there's nothing wrong with that other than they might not welcome new technology or new methods which might be why they all advised against using fibermesh concrete. They did not really state why other than it has no practical use in residential projects...HUH! But when I spoke to a concrete company the guy said the sub-base and control joints are the key. This guy even went as far as to say that if the base is prepared correctly and it is solid, no reinforcement is needed at all for a driveway. "Rebar and wire mesh will not stop cracking in flat work concrete", is what he said. "sub-base, sub-base, sub-base" is what he emphasized. So...I still don't know what direction to go. :(

I'll let you know what I decide.


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RE: Pouring a new driveway

This guy even went as far as to say that if the base is prepared correctly and it is solid, no reinforcement is needed at all for a driveway. "Rebar and wire mesh will not stop cracking in flat work concrete", is what he said. "sub-base, sub-base, sub-base" is what he emphasized.

This guy knows his stuff.

Mesh, no mesh or fibres or no fibres, doesn't matter as long as your base is done correctly. Wire, re-bar, fibres are much needed in walls and foundation work but a driveway slab, rather the series of slabs that make up a driveway do not need them.

Base; should be excavated such that all organic soil is removed and mineral soil should be removed until you get to undisturbed soil. You will see a shiny surface on the soil as the bucket moves along it at this point. And you might be a foot down too. You can bring height back up with pit run, well compacted.

Then a minimum of 6 inches of clear road base should be laid in two lifts, each one compacted by mechanical means. A plate compactor is minimum. I'd go at least 8 inches in three lifts using a small thumper roller or the biggest hand held thumper I could find.

The base should be a bit wider than the expected finished pour. Any drainage should be looked after during this phase, not during the pour and finish of the cement.

Ideally that road base should sit for a year to discern any bird baths in it but this is real world, eh?

Now, the smaller the slab, the better chance it won't crack. so design the pours in a series of small slabs, butted up to each other. Hint: slabs don't have to be square or rectangular. They can be triangles, circles, half moons. All depends on the forming. Leave each slab exactly a paver stone apart and run borders and cross lines. Have a series of small rectangles surrounding a circle made up of triangles that you stain or stamp. Whatever, the smaller the better but it also has to look good to you, right?

Last point; a 4" thick slab is almost twice as strong as a 3" thick slab for minimal extra cost. Anything thicker than 4" in residential work is past the point of a cost/return benefit.

Sorry this is so declarative and wordy but listen to the guy
at the concrete company.


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RE: Pouring a new driveway

Metaxa,
No need to apologize, I appreciate thorough and complete explanations. I have chosen to use the contractor the uses fibermesh reinforced concrete. Not only because I'm saving lots of money by going with him, but because he does come highly recommended and the people I have spoken to that have used him in recent years have had little or no problems with there concrete work.

I want to thank everyone for their opinions, it did help with my decision.

C R


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RE: Pouring a new driveway

C R,

Can you tell us how this is holding up now that it's been a few years? I'm on the same fence as you and live in a climate that has freeze cycles as well. Also if you could tell me how big your slab is and if there is "any" reinforcement at all that would be great! Thanks in advance for the insight.


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RE: Pouring a new driveway

Poor driveway with a footer 8x8 on the perimeter with a #5 rebar continuous and #3 rebar both directions underneath at 2' on centers. Cut the drive in sq. sections and cut it deep. Make sure this drive is at least 5" thick. You will have no problems at all and you can let a Mack truck full of rock park on it daily.


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