For a driveway in your area I would recommend this:
1. Make sure the sub grade is solid. Best way to test it is drive a large heavily loaded truck on it and any areas that are moving when the weight of the truck rolls over it should be removed.
2. Fill any low spots in the sub grade with ABC stone and compact it with a mechanical tamp or vibrating roller. Keep the stone damp when compacting. Apply water if needed. (#57 washed stone could be used and would not require tamping but it is also more porous and will tend to hold water and could deteriorate the sub grade later on.)
3. Many contractors will use 4‚Äù of concrete for a driveway to save money, but I strongly suggest you use 5‚Äù with 6 x 6 10 x 10 welded wire reinforcement. Be sure the concrete finishers pull this wire up into the concrete and do not just pour over the top of it. For additional insurance against unwanted cracking you can have fibers added to the concrete at the plant.
4. The concrete should be poured at a 3‚Äù ‚Äì 4‚Äù slump maximum. (Specify this when the concrete is ordered and do not allow the concrete finishers to add excessive amounts of water after it arrives on site.) If the concrete is too wet when it is placed, it will shrink more when drying, and thus be more likely to crack.
5. Cut control joints in the wet concrete every 20‚Äô and place an expansion joint every 40‚Äô.
Immediately after the concrete is finished apply a dissipating concrete sealer to the surface to insure it will not dry out too fast. The sealer will last about 30 days holding in the moisture to insure the concrete will cure to it‚Äôs proper strength and then it will dissipate.
[This message has been edited by GlennG (edited April 02, 2002).]