');

Driveway with no reinforcing?


Thread Tools
 
Search this Thread
 
  #1  
01-10-07, 04:13 PM
F
Member
Thread Starter
Join Date: Jan 2006
Location: Atlanta, GA
Posts: 11
Received 0 Votes on 0 Posts
Driveway with no reinforcing?

I am getting ready to have 60 yards of concrete poured. Application is a 12' x 220' driveway & a large pad.

The contractor is recommending 3,000 psi with no reinforcing. No fiber. No steel. Nada.

This seems wrong; however, the contractor has many projects under is belt over the last 20 years. He is admant that he would handle is personal driveway the same way.

What do you guys think?
 
  #2  
01-10-07, 04:36 PM
Join Date: Mar 2005
Location: USA
Posts: 6,130
Received 0 Votes on 0 Posts
Driveway with no reinforcing?

I would not have it done without wire mesh and sawn control joints. Some will opt for fiber mesh also. If I had my choice between the two, I would go with wire mesh. Neither are classed as structural reinforcement although some argue that the wire is.

Where are you? - It sounds like a minimal spec for the materials.

Here we have freeze thaw durability to face. You will be hard pressed to find a supplier that will sell or stand behind anything less than 4000 or 4500 psi air entrained concrete. Good contractors will not use less. The in and out guys and moonlighters will fins a way to get lesser concrete.

Dick
 
  #3  
01-10-07, 06:26 PM
P
Member
Join Date: Feb 2005
Location: USA
Posts: 1,396
Received 0 Votes on 0 Posts
Basically, I agree with Dick. However, around here I think 3,500 psi is about the minimum to be trusted on a driveway. I always pour at least 4,000 psi with Nycon fiber. We also use rebar around perimeters and spaced throughout the slab. We don't necessarily tie a 2x2 grid, but we use quite a bit of rebar.
That said, I have torn out and replaced many a driveway that was still structurally very sound and contained absolutely no reinforcement, wire or fiber. They held up fine, and we only replaced them because the top was pitted, not because they were coming apart.
My advice would be to trust your contractor. If you are uncomfortable though, have him sign an agreement that if the slab fails in x number of years, he will fix it at his expense. Make sure to spell out what constitutes a failure to you (i.e. cracking and separating, differential settling, surface delamination, etc.).
Keep in mind though, that just because a slab has reinforcing, there is no ironclad guarantee that it won't fail anyway. Preparation of the base plays a huge role as well, in addition to what type of traffic it is exposed to, etc. Good luck.

Pecos
 
  #4  
01-10-07, 08:06 PM
F
Member
Thread Starter
Join Date: Jan 2006
Location: Atlanta, GA
Posts: 11
Received 0 Votes on 0 Posts
Thanks guys. I live in the Atlanta, GA area. (& have edited my profile as such).

Are you guys saying concrete with a lower PSI rating in a milder climate will "perform" as well as a higher PSI rating in a colder climate?

About the sawn control joints: he is going to provide joints; but, they will not be sawn. His guys will use the point of a tool (trowel?) to make these grooves. Is this method normal?

How soon after pouring can vehicles (4,200 lb car & 5,500 lb truck) use the drive?
 
  #5  
01-10-07, 08:47 PM
S
Group Moderator
Join Date: Oct 2004
Location: WI/MN
Posts: 19,844
Received 140 Votes on 121 Posts
My parents had a new driveway poured in Minneapolis last year and city code stated that no reinforcement could be used in the last 30 feet before the street. If it's the right concrete, no reinforcement can be ok.
 
  #6  
01-10-07, 08:54 PM
P
Member
Join Date: Feb 2005
Location: USA
Posts: 1,396
Received 0 Votes on 0 Posts
No, I'm not saying that. Dick and I live in similar climates. I personally feel that a very minimum of 3500 psi concrete could be adequate, while I think Dick is saying 4,000-4,500. We just disagree on that minor point. In my own business, I use 4,000 minimum though, just for my own peace of mind. I would be a bit leary of 3,000 with no reinforcement, but as I said, I've seen it hold up well too. It's just a judgement call.
I tell all my customers to keep vehicles off their new driveways for AT LEAST one week. Longer in colder weather, however in Georgia I'm sure it never gets that cold.
Placing joints with either a saw or a bladed tool is acceptable and common. The joint should be at least 1/4 as deep as the slab is thick though (1 inch deep for a 4 inch thick slab, 1.5 inches deep for a 6 inch thick slab, etc.) The bronze joint tools used for cutting the joints can wear down quickly, so make sure your contractor uses one that is at least 1 inch deep.

Pecos
 
  #7  
01-11-07, 11:51 AM
M
Member
Join Date: Feb 2004
Location: wv
Posts: 399
Received 0 Votes on 0 Posts
concrete

I am not a concrete finisher, but if it were me having it done, I would have the contractor put in the re-bar, mainly because it would not be that expensive for the piece of mind it gives you, remember something other than a car might need to come on to your slab.
 
  #8  
01-12-07, 02:47 PM
P
Member
Join Date: Feb 2005
Location: USA
Posts: 1,396
Received 0 Votes on 0 Posts
You know, the psi we're talking about is a measure of compressive strength. 3,000 pounds PER SQUARE INCH! Certainly a 3,000 psi mix will hold a car and other traffic without crumbling, but in my experience I just think a 4,000 psi or more finishes better. A vehicle's weight is spread evenly over 4 points (or more) on the slab, each measuring roughly 30 square inches or so. By that measure, the vehicle would have to weigh over 360,000 lbs for the concrete to actually be crushed by it. So the concrete's compressive strength isn't the issue, it's the reinforcement. Will the concrete have the tensile strength it needs?
My best advice is to trust your contractor. If he's been in business that long, he probably knows what he's doing. I personally would feel better with reinforcement of some sort though.

Pecos
 
  #9  
01-12-07, 03:41 PM
Join Date: Mar 2005
Location: USA
Posts: 6,130
Received 0 Votes on 0 Posts
Driveway with no reinforcing?

The 4,000 to 4,500 psi requirement our local suppliers and many contractors have established is not for structural purposes. Tests have shown that stronger concrete has far superior durability for freeze/thaw resistance. This is not the only durability facror and certainly this type of concrete must be air entrained. The extra cost is cheap insurance.

Many cities have a requirement for a portion of the driveway to be non-reinforced. The reason for this is that a portion of the driveway is on city property and may be subject to removal for any utility construction. Without the rebar and mesh, removal is easier. Of course the city has to replace it after construction.

I had the same non-reinforced restriction when I was in Michigan. This was limited to the driveway from the street to the sidewalk.

Dick
 
  #10  
01-12-07, 05:25 PM
Group Moderator
Join Date: Dec 2004
Location: USA
Posts: 28,077
Received 1,212 Votes on 1,098 Posts
frank29, you never mentioned how thick the driveway will be? Just wondering.

I poured 30+ yards for our driveway at our warehouse, (3 stalls wide, maybe 30' long?) Did it on 2 seperate days- used 2x6 forms and made a keyway in the first center pad, then removed its form and poured the 2 pads on each side the following day. At roughly 5" thick, using 47B mix, it doesn't have a crack yet. (The 3" of rain we had the night before on top of my packed sand didn't hurt matters either!)
 
  #11  
01-13-07, 07:11 AM
F
Member
Thread Starter
Join Date: Jan 2006
Location: Atlanta, GA
Posts: 11
Received 0 Votes on 0 Posts

Originally Posted by XSleeper
frank29, you never mentioned how thick the driveway will be? Just wondering.....
4" thick.

The pour was yesterday. "We" (hey, I watched!) used 63 cu yds. I ended up following my contractor's advice.....I've got my fingers crossed.

Thanks for all responses.
 
  #12  
01-14-07, 08:43 PM
T
Member
Join Date: Mar 2006
Location: Austin, TX
Posts: 1,405
Received 0 Votes on 0 Posts
It is too late for you, but the bottom line is that concrete will crack. If nothing else, wire mesh will hold the pieces together, while fibermesh will help prevent some cracking altogether. I would never pour a driveway without perimeter rebar reinforcing (and small beams, for that matter), wire mesh and closer-than-recommended control joints, with fiber if it was decorative in any way (stain, pigment, exposted aggregate, or stamping). Why not, the cost is minor compared to the overall project expense anyway?
 
  #13  
01-21-07, 01:35 AM
Member
Join Date: Jan 2007
Location: Hillsboro, OR
Posts: 7
Received 0 Votes on 0 Posts
It is probably a regional thing. Out here in the west as a default we do not use rebar, mesh or fiber in driveways unless specifically requested by the builder or homeowner. That assumes of course the driveway is being placed on a solid ground base with appropriate amount of gravel. If it has been built up extensively with gravel or the excavation was done improperly we will then use such material.
 
 


 
Ask a Question
Question Title:
Description: