Best Base For Concrete Driveway

paintguy

What the best base for concrete driveway (have clay soil sub-base) ? How thick you would go ? Now I have just the sand, no rebar and concrete is cracking on the approaches. Driveway is 3 years old . Live in Michigan.
Thanks.

cleveman

You should move away from Michigan. Look at your neighbors' drives. I bettcha they are all cracked up too.

I think the portland concrete association will tell you on residential to just pour on the ground, which is what you have already and you can see how well that is holding up now can't you?

You should have at least a 4" base of compacted gravel and it should be well drained. When you drive along the roads there, you might notice that the ground slopes away from the roadside most of the time. This is the drainage.

Don't worry about reinforcing the concrete when you pour it. If it cracks up, you can always go back with a router with a diamond bit and retrofit some re-bar and epoxy it in place. No need to be a pessimist.

Like they say at the electronics store, "be glad you got three years out of it. There was a woman here before you and hers gave up after a month".

concretemasonry

Definitely use at least 4" of compacted base.

For your climate, when you pour the concrete, make sure you use 4000 psi minimum strength AND it is air entrained.. Also, make sure you saw control joints withing 24 hours (hopefully 8-10 hours after the pour. This is far more effective that sawing random. crooked cracks plus it looks better and is cheaper. We used a 3" slump and did not pour "soup". In Minnesota, 4500 psi air entrained concrete is common.

When I put in my driveway in northern Michigan, I used both wire mesh and fibers in the concrete. If I had to cut corners and use only one of them, i would forget about the fibers.

In northern Michigan, my driveway was put in almost 20 years ago and there is NOT A CRACK in it now. Only very few (10 or so) very small (1/4" max.) pop-outs from the Michigan aggregate that are almost impossible to eliminate at a realistic cost.

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Dick

Engineer, designer and consultant recently active domestically and internationally on construction and design in about 35 countries.

jaros bros.

A soil engineer would be able to spec it out for you. Usually in a situation with expansive clay and poor conditions 4' of material is removed. Drain tile and frost free material is hauled in. I can't imagine not adding rebar to the concrete. 1/2" rebar two foot on center will do an amazing job. Course all this adds to the cost of the job which is why everyone tries cheats as much as they can, and sometimes you get lucky, and then sometimes you end up paying all that and more to have it done again the right way.

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Josh Jaros www.jarosbros.com Remodeling in The Woodlands, Texas

jaros bros.

I'm not really impressed with the fiberglass. From personal experience it is just for small cracks and cosmetic stuff. I have seen a lot of slabs with just fiberglass crack. Of course that could be because the prep work was bad too.
For the base crushed rock follow by a layer of filter fabric and then a layer of sand to place the concrete on.

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Josh Jaros www.jarosbros.com Remodeling in The Woodlands, Texas

AutumnWood Inc.

To answer your question: Crushed limestone...
In my opinion, it is all in how you prep. If you know there is settling issues, I would take out more clay, and put maybe 8" of crushed limestone base in, and compact every 4" .. Use fiber mesh and wire when you pour, etc. My 2 cents

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CaliDesigns

I use recycled concrete. It's not as porous as limestone.

paintguy

So the last layer of base would be sand ? Why not go with just a rock ? What about 'wash off ' problem with sand ? I think that's what happening now with the driveway.
Thanks

concretemasonry

A layer of sand is not good. You will never see it on a highway or commercial building.

Sand can wash out, especially if it is fine, since it cannot be compacted and can be unstable.

You can't beat a good compacted base to the proper elevation to put concrete on. Some people are sloppy and use sand as a cheap and easy leveler, but it can draw the moisture out of the slab preventing proper curing of the concrete. Filter fabric does nothing but add to the cost.

__________________
Dick

Engineer, designer and consultant recently active domestically and internationally on construction and design in about 35 countries.