Replies

1. 
   CountryBumkin | Aug 01, 2016 04:19pm | #1

   I'd like to know the answer myself. I'm planing on a concrete driveway and knowing what should be used for base material would help me too.

   Maybe you should ask your questions to the contractors (report back what is said) and see which has the best warranty.

   Good luck

2. 
   DanH | Aug 01, 2016 06:29pm | #2

   You will notice that the first bid is putting in more rock than the second bid.  I don't know what specifically is the difference between the two stone formulations, but the deeper the foundation the stonger the surface.

3. 
   spclark | Aug 05, 2016 09:16am | #3

   Ever follow progress when a major road surface is being constructed?

   Preparation will always be 90% of the work doing a job that lasts.

   Where I am now (central midwest) I see Interstates and major hiways getting 12-18" of stone compacted down then 10" or more of concrete slab put on top, sometimes covered with a 3"+ layer of asphalt for final road surface.

   I moved into a '70's era home three years ago that had its original blacktop driveway: 2-3" of topping laid directly onto scraped clay subsurface.

   No drainage, maybe a little sand here and there for fill.

   When we found the house listing on-line it was evident from the pictures that the driveway would need replacement as task #1; looked like pictures of a lava field.

   That had to wait until our first spring. Trying to clear snow that first winter nearly landed me in the hospital more than once; it was so broken up from heaving & having vehicles sitting on it when covered with snow & ice it was treacherous to walk on.

   Cost me $3,500 for 4" concrete placed atop 4" of crushed stone w/ #4 rebar (1/2") every 6' & 6x6 wire under the whole thing.

   Since then I've watched it heave nearly 2" in the winter (there's still that darned clay underneath all the crushed rock!) but it hasn't cracked and returns to level once the frost is out of the ground.

   Depending on how long you want to live with that driveway, and of course what you want to park on top of it during hot summers / soggy springs, I'd go with whatever I could afford to invest in setting up a well-drained, stable base under the (relatively) plastic asphalt compound used for the top surface.

   As a postscript, usually the higher the number for aggregate the coarser the material. #6 will drain better than #4 so I'd go with estimate #1 given a choice, or look for more after specifying for a deeper sub-base.