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Adding a drive
06-12-2013, 17:25
Post: #1
Adding a drive
I'm looking at finishing out the rest of my drive for my birdhouse. Here's my dilemma:

The original drive was done with 6" 3500psi concrete and 3/8" rebar on 24" OC. It cracked the first time I drove over it (this was AFTER it had cured for at least 30d). It now has numerous cracks in it and has been driven over about 30 times total.

So in considering the new drive, I want to avoid that cracking. I fully understand that some cracking is inevitable, especially with the spongy soil I've got, but the parking slab is subjected to MUCH more long term weight and only has a few cracks in it, all of which are due to soil, not bus weight.

I'm being told that wire mesh will help avoid the cracking, but not finding much corroborating evidence to back up that claim online.

So do I stick with the rebar or try the wire mesh? The drive will not normally have anything parked on it and the heaviest thing driving across it will be the bird.

John Mace
96 42 big bird
living in the wild hinterlands of the north
free to roam without the man getting me down
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06-12-2013, 19:41
Post: #2
RE: Adding a drive
Try rebar or wire mesh that is used on interstates. Usually you have specify that grade of wire.

Steve Gureasko
90 WBSA "Jus Chillin"
Ponchatoula, La.
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06-12-2013, 21:15
Post: #3
RE: Adding a drive
I would suggest over engineering it this time. I did mine with 6 " thick 5000 psi and used #3 rebar (3/8") on 6 inch centers, where the bird would NOT sit or drive. I used #5 (5/8") on 6 inch centers where the bird would drive and sit. My footings around the edge are 12 inches wide by 18 inches deep loaded with rebar. I wanted to be able to jack it up while sittiing in the barn.
Have fun and good luck![/u]
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06-13-2013, 09:52 (This post was last modified: 06-13-2013 10:33 by davidbrady.)
Post: #4
RE: Adding a drive
I'd stick with rebar and I'd add lots of it like Bob suggested (on 6" centers). Use high tensile rebar (60,000psi), and place it 2" from the bottom of the slab, so if you have a 6" slab you'd have 2" of concrete, then rebar, then 4" of concrete. When the slab bends it's the rebar that goes into tension adding tons of strength. The top concrete goes into compression, also adding tons of strength, the bottom concrete beneath the rebar is there for show. :-) (actually it's there to protect the rebar and to transfer loads into it, but it does nothing for the flexural strength of the beam. Add soft cut's to control shrinkage cracking, (10' x 10' grid).

If you use wire mesh you need to calculate the cross section area and make sure you have enough. If you're using #5 rebar like Bob suggests then make sure the wire mesh has the same amount of steel in it; i.e., say you have #5 on 6" centers then for every 6" depth of concrete you have (pi*.098=0.31 sq in of steel) cross section area of rebar. Do the math with screen mesh and see if you get 0.31 sq inch in every 6" depth. (measure the wire diameter, take the cross section area, and add up the number of wires in a 6" depth).

Simplified Engineering for Architects and Builders, Ambrose, J. TripenyTripthy, 10th edition, John Wiley &HobokenHoboken, New Jersey.

david brady,
'02 Wanderlodge LXi 'Smokey' (Sold),
'04 Prevost H3 Vantare 'SpongeBob'

"I don't like being wrong, but I really hate being right"
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06-13-2013, 11:08
Post: #5
RE: Adding a drive
Wow, this is all getting to sound very expensive... What about the fibered concrete like used on runways? Is it way more expensive?

Karen and Adrian Abshire
Full Timing in 'Mauvelous', our 1990 Bluebird Wanderlodge WB40 PT
'... if we ain't having fun it ain't worth doing ...'
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06-16-2013, 11:34
Post: #6
RE: Adding a drive
there is lots of discussion on this topic at the garagejournal forum. have a look over there.

tom

2002 Two Slide Newell Coach 608 DD Series 60, Allison 6 speed
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09-12-2019, 11:56 (This post was last modified: 10-01-2019 13:00 by neontwister.)
Post: #7
RE: Adding a drive
I am getting a slab poured along with a new back driveway. I have been lurking and reading. I am going with 30 yards of 5000 psi concrete , 6 inches thick with a 12 inch footer around the edge and a big rebar, I think they said 5/8ths on 6 inch centers. Its 18, 45 pad with a 30 foot 10' wide driveway. I wanted a real steel building but the county said I had to have lap siding and the local steel company said they don't do that. I am getting a Carolina Carport finished on all four sides , insulated with a 10 / 14 roll up door. They say it meets all Florida wind ratings and has state mastered plans. I have to wait on the plans as every garage is a little different. Waiting on FDOT to okay the new culvert and then its fly time. This concrete guy is pushing. I like that. I got a tree stump already dug up and a pile of dirt as big as a car out there. Hopefully FDOT is a go tomorrow and I can pull permits, or Monday. Worse case I shift it a little west to the center of the yard. Will send pics soon.
─░mage

So far so good. Didn't help my county had its servers hacked. They were down for a week. Now another week before I can form and pour.
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09-12-2019, 12:05
Post: #8
RE: Adding a drive
Sounds like a good start! I hope it all goes off with minimal hitches.

John Mace
96 42 big bird
living in the wild hinterlands of the north
free to roam without the man getting me down
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