Evaluating bids for concrete driveway

Have obtained 2 bids for an approx 3400 sq ft driveway
Both bids specify 4" of 4000# concrete, finished and sealed, with sawed control joints. One bid specifies 6x6 6 ga. wire reinforcement, the other specifies 3/8" rebar 3' on center. Would one be preferable to the other? Is 4" enough thickness, for a residential driveway? I'm in Indiana, so winters almost always have a couple of periods where the lows are below zero.
Existing driveway is gravel, depth unknown, about 5-6 years old. Getting pretty weedy.
The bids vary a lot, one being $4.60/sq ft the other about $3.10.
Anything else to consider, or ask for clarification on? Neither bid mentions much about excavation and sub-grade prep, though it was discussed verbally with both contractors.
Allan
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go with the welded wire mesh and pick up some #4 bar from lowes or wherever put some bars where the street transition is and the garage entry and if you park your truck outside around where the tires are. If you have a culvert under the driveway put some in there as well. I also live in Indiana. Expect your property taxes to go up in 2 years as well. Rebar is cheap and not rocket science to put down. One word of warning the mesh MUST be pulled up into the concrete, leaving it flat on the ground is useless
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6" works best if your long term and don't want cracks Wire mesh or fibremesh equal Rebar on thickened perimeter and @ tie in areas
No decision as to removing the gravel ? Concrete should be over compacted soil with vapor barrier although driveways don't necessarily need the vapor barrier
kickstart
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Thickness is adequate for standard residential automobile traffic. But, not concrete trucks or heavily laden delivery trucks like one delivering topsoil to the place for instance.
You should have perimeter beams for both water erosion protection, and when your car may drift off the perimeter of the driveway.
Be sure the apron at the street is well reinforced with rebar as the pointed edges seem to want to break off first. Be sure the street apron provides drainage for the shoulder, not diverting water on your property. If the street has a curb, be sure the curb is replaced properly.
Don't sign anything unless the party specifies excavation and preparation, and cleanup afterwards. This should also include topsoil replacement where the forms were removed.
--
Jonny



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snipped-for-privacy@mailinator.com wrote:

Allan, The APWA suggests that 4" is not a sufficent depth for vehicle traffic and that 6" be installed. However, many 4" drives have been in for years without major problems. If #4 bar is installed it must have 3" of cover between it and the earth. It must also have 1 1/2" minimum cover over the top. This would be 3 + 1/2 + 1 1/2 or 5" minimum.
Mesh can be used, however it is hard to get it into proper placement and keep it there. If mesh is used i would suggest that mat and not roll material be used and that you get chairs to maintain proper placement.
Bar can then be placed at the perimiter and dowled and epoxied into existing concrete at locations where the concrete depth can be made to accomidate.
Terry Combination Building Inspector
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First of all I would give the contractor that included the rebar extra consideration. Yes wire is adequate and meets code but if after you have removed as much concrete as we have in a lifetime you realize that wire is slightly better than fiber which is completely useless. You mentioned sealed what are you refering to? A standard finish slab (not stamped) would not require a sealant.. Also with todays redi mixes I will gaurantee you will get cracks a savy contractor will know this and place the joints at a proper depth and orientation to controll these cracks...but unfortinutally even with the best effort it still cracks where its not supposed to. 4" should be just fine for where you are we allways make the perimiter a little thicker usually about 3" just for insurance.
Neither bid

get specific clarification on this. The majority of time (labor cost) is eaten up in this step, forming and pouring is the easy part. The condition of the existing drive way must be examined befor proceeding. Being that it is gravel and has been in use for several years is a plus you have been essentially compacting it for several years now. On the other hand areas that collect water must be looked at and fixed. One final note about rebar VS wire mesh..simple test take a piece of rebar 1 foot long and a piece of wire mesh 1 foot long and see which one you can bend...
snipped-for-privacy@mailinator.com wrote:

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Italian wrote:

"Broom" finish was specified, followed up by "commercial grade sealant"

Meaning, 7" at the perimeter?
Allan
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MAny thanks for all the info. I am going to get one more bid before I decide anything.
Allan
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Allan, 4 inches is standard thickness for residential driveways in Indiana. As others have stated, it is rare that wire mesh, either roll or mat, is located properly in the middle of the slab with sufficient cover to avoid corrosion. I would suggest fibers instead of mesh. The fibers make the concrete mix more homogenous, and reduce cracking during the placement and curing of the concrete, so that there are fewer cracks in the final product. Make sure that the contractor is placing joints no more than 10 foot apart, and as square as possible, and is placing expansion material between the driveway and any other structures or concrete. Curing is the most neglected and one of the most important steps in installing a quality concrete driveway. A driveway installed with 4000 psi concrete mix, properly finished but not cured properly, will have a top surface of 2500 psi concrete that is very porous, and it will be more likely to have surface defects with freezing and thawing, and especially with de-icing chemicals. The Indiana Ready Mixed Concrete Association, (where I work), is a Non-Profit organization promoting quality ready mixed concrete in Indiana. We have residential concrete guidelines available for homebuilders, contractors, and homeowners. You can go to www.irmca.com to get in touch with us.
Brian
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