Bag Mix Rating for driveway

Hi all,
I recently got a quote for a driveway replacement. The quote was to use concrete with a bag mix rating of 6 with a thickness of 4 inches. Wire mesh reinforcement. I saw plumbbob make a reference to bag mix ratings so I thought I would shoot the question to the forum.

Driveway width of 10 feet with joints in it at 5 feet across and every six feet down the length of the driveway.
Does the bag mixture sound sufficient for a driveway in southern Michigan? It will not be used to park any heavy equipment. At most, a mid-sized sedan.

Thanks for any advice

 

A 6 bag mix would be the minimum.

5 bag mix = 2500 psi concrete.....generally used for footings

6 bag mix = 3000 psi.......the minimum I'd use for a surface type concrete

7 bag mix = 3500 psi ........ and so on....

The "Pounds per Square Inch" rating is a bit misleading......the rating for footing concrete would also hold about any vehicle you would park on it ( including your house ).......but the higher the PSI or bag mix, the more Portland cement in the cubic yard.

What that does do, is give a better surface finish. As you increase the cement, the finisher has more to float to the surface and you get a denser finish that will resist surface cracks, chipping, etc......assuming of course it is finished correctly ( not allowed to freeze or get too dry during curing ).

As too cost, to go up a "bag" per yard generally only costs $3 to $5, which is a pretty insignificant cost on most home job.....I'd use at least 7 bag mix personally.

 

The driveway will be subject to freeze-thaw and road salt, right??

Given that, I always recommend 4000 psi concrete, air entrained, 4" slump to my clients. Will give you the resistance you need to salt and freeze-thaw. We don't really worry about the number of bags of cement per yard (although have seen some specifications say min. 6 bags for exterior concrete); that's left to the ready mix company to design the mix to achieve the desired results.

Bruce

 

Thanks for all the advice. The driveway will definitely be subjected to freeze/thaw and roadsalt. I'll ask for a revised quote with an increased psi rating.
As always I am astounded at the level of knowledge these boards provide as a resource.

 

Or rather, on re-reading, I'll call and check to find out what the psi rating is for the 6 bag mixture they will receive from the ready-mix company.
Thanks again.