how to make sure that driveway does not crack

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I am thinking about hiring a concrete company to redo out driveway and other concrete work. What I really want is that the driveway should stay level and crack-free for years, as cracks seriously nterfere with my material handling. How would I ensure that? Is that a matter of putting more gravel, more concrete, different concrete, or what?
thanks
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Ignoramus21090 wrote:

A RELLY GOOD base with proper drainage, then thick concrete with mesh and rebar tying the sections together.adding fibre to the concrete and a high strength mix helps too. how heavy loads on this driveway?
you can build iut to airport runway specs if you dont mind spending a gazillion bucks.
poor drainage is a major trouble, and realize concrete doersnt last forever.....
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snipped-for-privacy@aol.com wrote:

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But properly done, concrete can last over 100 years. Preparation and a good base are very important. Take a look at what id done when building roads.
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Not very heavy, up to 1,000 lbs with cart. The problem is that cracks make moving said cart painful.
thank you.
i
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Rebar, lots and lots of rebar. And concrete 6" thick. Did i mention rebar?
--
Steve Barker

"Ignoramus21090" <ignoramus21090@NOSPAM.21090.invalid> wrote in message
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wrote:

Except lots of rebar can also mean lots of spalling. Rust requires more room than steel and can explode the concrete.
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snipped-for-privacy@the.shoppe wrote:

be in the lower third of layer. How do you explain the lack of spalling on exposed concrete pillars, e.g., bridge supports, basement supports, etc. since they have lots of rebar.
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On Sun, 07 Jan 2007 23:30:41 GMT, "George E. Cawthon"

Do a little net search. Spalling is an IMMENSE problem in concrete structures.

They generally know what they are doing.
In Quebec recently an overpass collapsed killing people. Spalling is the probable cause.
Spalling in concrete on the ground can be very bad due to the moisture. There is such a thing as TOO much rebar.
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snipped-for-privacy@the.shoppe wrote:

Rebar corrosion....one of the causes of spalling
is strongly dependent on the thickness of the cover (amount of concrete over the rebar), soundness of the concrete & the local environment.
a marine environment is probably one of the worst as is one where snow removal chemicals are used
general cover suggestions
air 2" soil 3" marine environment a lot more
another cause of spalling is freeze thaw but I doubt we're concerned with this on the OP's driveway
plus to add "too much rebar" to a slab it would have to be quite a bit....I'm sure the OP's driveway project will get less than minimum temperature (if it get's any)
btw I'd wait until some investigation work has been done before suggesting a reason for the Quebec overpass collapse you mention.
This isn't the first collapse.
cheers Bob
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SW Michigan. I know several 40 year old bridges where they had to replace or cast over and make thicker the pillars, and parge the supporting beams. All recent projects around here are designed with coated steel and replaceable decks instead of concrete over steel. Sure, there is still concrete in them, but they are designed so the salty crud doesn't saturate the concrete and rot the rebar. A couple historic bridges had to be torn down, due to the left-in-place steel forms under the concrete arches rotting out.
Didn't somebody develop rust-resistant rebar a few years back? Special alloy, some sort of coating, and some sort of field prep kit for welded and twisted joints?
aem sends...
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snipped-for-privacy@att.net wrote:

and twisted joints? <<<<<
Epoxy coated rebar but the coating is easily damaged during placement care must be taken
Stainless steel rebar does exist but the cost is high.
cheers Bob
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Salt (more properly, chloride ion from whatever source, i.e. sodium chloride or calcium chloride) used for deicing is the primary factor causing the failure of concrete structures on highways. Also, you'll find contractors who'll want to add calcium chloride to the mix to accelerate strength gain so that they can get the finishing over with and move on to the next job. Except in emergency repair situations, DOT's generally won't allow the use of calcium chloride in concrete. There are accelerators that don't cause corrosion, but they're more expensive than calcium chloride.
In a normal concrete mix, reinforcing steel will quickly form a passive coating and no rusting will occur for many, many years. If you apply chloride deicers, the chloride ions will gradually work their way down to the reinforcing steel. When the concentration of chloride ion gets high enough at the surface of the steel, the passive coating breaks down and rusting ensues. Since the rust takes up considerably more space than the steel it was produced from, the pressures can become high enough to rupture the concrete overlaying the steel (much like a tree root opening a crack in a rock). Concrete bridge decks fail at the highest rate since they have so much steel and more deicer is applied to them because ice forms there first but the rest of the bridge suffers also from splash and seepage.
Concrete slabs will crack eventually and it will happen more quickly if you haven't added sufficient expansion joints. Since you can't totally prevent the cracks, your best bet is to use reinforcing steel so that the cracks won't go anywhere once they form. If you put really heavy loads on the driveway, you'll have to include load transfer steel at each expansion joint.
If you absolutely must use large amounts of chloride deicers, then consider reinforcing with epoxy coated rebar. If you use epoxy coated rebar, you'll have to be on your toes to ensure that the epoxy coating isn't damaged during placement of the steel and you'll have to inspect the epoxy coating before placement to be sure it wasn't damaged (chipped, cracked) during shipping/handling. Damaged epoxy coating can sometimes cause more problems than not having epoxy coating at all.
Harry

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Ignoramus21090 wrote:

Another Idea to make sure it doesn't crack is to make sure that u try and keep it as cool as possible while it is curing,spraying water on it at different times,but be sure not to mess up the finish,and u could use expansion joints,good concrete co. should already know this. Hope this helps
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Keeping it damp is what is important not cool. High temperature steam curing is often used for high strength concrete.
You can't re wet concrete. Once it dries it stops curing. 10- 30 days of keeping it damp will get you very strong concrete.

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Ignoramus21090 wrote:

check out these threads about driveway thickness, prep & design
http://groups.google.com/group/alt.building.construction/browse_thread/thread/e2ee10a29923432e?hl=en
http://groups.google.com/group/alt.building.construction/browse_thread/thread/f3ee6bae21e8fa81/42eeb270cac427b5?lnk=gst&q +driveway+rebar&rnum=1&hl=en#42eeb270cac427b5
cheers Bob
short answer: good base, 6" thickness & crack control joints every 150 sq ft
prep is more important than mix but a low water ratio & a decent amount of cement in the mix help (3000 psi min)
I like rebar or mesh but lots of people (more expert than me) don't. think it's necessary
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It is going to crack, eventually. Expansion joints and scoring are recommended in addition to a good base, adequate thickness, reinforcement, proper curing and so on.
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On Sun, 07 Jan 2007 12:41:50 -0600, Ignoramus21090

Use bricks.
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bricks move and get uneven faster than concrete.
might be better to use asphalt and know in advance it will need repaved.
or asphalt over concrete.........
nothing can be perfect and last forever...
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snipped-for-privacy@aol.com wrote:

Yea, but it is easy to correct and the next time it takes far longer. After a while they get very very stable. Of course that assumes they were put in properly in the first place.

--
Joseph Meehan

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