Replies

1. 
   FrankB89 | Apr 29, 2002 08:35am | #1

   Don't know your geography but in my area (west coast), I'd lay a base of 2 1/2" minus about a 4" lift, compact it, lay on another 2" lift of 3/4" minus and compact.

   When it comes time for asphalt, your contractor will have a good base to just dress up.

   Another item that helps, if you're in a wet climate, is to lay a mat down on your bare base prior to laying in the rock.  I can't recall what it's called, but it's a black fabric, like landscaped mat, but heavier.  Helps shed water and keeps your rock base up where it belongs.

   Measure it with a micrometer, mark it with a piece of chalk and cut it with an axe.

1. 
   byrd48 | Apr 29, 2002 06:31pm | #2

   Thanks, I'm in Atlanta and the driveway is hard packed red clay with some clay rock. I've gotten it excavated about 2" so far. I think I'll go another two inches and drop the gravel.  Do you know which gravel in particular is best?

   Thanks

   Jon

1. 
   FrankB89 | Apr 29, 2002 11:31pm | #3

   Out here, it's pretty much basalt.  Make sure its crushed rock, of course.  If I were you, I'd pose your question to your prospective asphalt guy.  Might save you some time and money in the long run.  Also, take drainage into account while you've got your ground torn up.  Measure it with a micrometer, mark it with a piece of chalk and cut it with an axe.

1. 
   brownbagg | Apr 30, 2002 06:14am | #4

   57 stone

2. 
   danusan1 | Apr 30, 2002 06:57am | #5

   Use some type of crushed material 3/4"or larger, not sure of the material in your area but sure that their is probably some type of mining operation in your area.  The jagged edges will allow you to get good compaction. Previous post suggested fabric before installing stone which isn't a bad idea, most of these products are produce by the big petro co.  I have used these products in wet sites and have installed oversized crushed concrete 6"deep and have been able to roll in gravel trains, concrete trucks, etc. with out getting stuck, where previous to installation you couldn't even get a pick-up into site.  For driveways I would typ. install approx. 6" of material. the larger the the size material the less it will sink over period of time, when you are ready to pave driveway you probably will have to bring in some finer material to grade in.   Check with co. in your area that sells silt fence they usually sell the fabric.

1. 
   AndyEngel | Apr 30, 2002 10:45pm | #6

   The name of the gravel varies geographically. In NJ, it was DGA (dense graded aggregate). Here in CT, they call the same same stuff quarry process, process, QP or blend. In PA, I think is was something like DOT 57. The key is that it be crushed stone with angular edges, not graded, round riverine material, and that it be a mix of sizes right down to dust. The small stones fill the voids between the large ones, creating a dense, weight distributing layer. The thicker this base, the greater an area of subsoil that the base distributes the weight over. Think of the weight being spread out by the base in a cone shape, with the sides of the cone being something like 45 degrees. This can be really important over clay soils, which have the bearing capacity of Jello when they're saturated. A layer of larger material at the bottom is a good idea, followed by a few inches of 3/4-in. blend, which is easier to get a fine grade on. Take this opportunity to make sure that the subgrade and each succeeding layer (the base and the asphalt) are graded to drain.

   I doubt that the rock itself matters much, as long as it's not too soft. I've used crushed limestone, granite, marble and quartzite. On Long Island, where there's no bedrock to speak of, it's common to use crushed recycled concrete.

   Andy Engel, Forum moderator

3. 
   Boxduh | May 01, 2002 12:47am | #7

   It is called something different wherever you go.  Here in upstate NY, they call it 'Item 4' or commonly, 'crusher run.'  Item 4 refers to some chapter in the NY DOT highway and road building specs.  It is best to call your local gravel quarry that sells to the roadbuilders and pavers, and ask them what is used for road and parking lot base.  Make sure that the substrate earth, be it clay, sand, or whatever, is sound and graded, before going on with the paving base material, and get the base compacted well before blacktopping.  I am getting a job done at my home next month, and atop the 6 to 8 inch base of item 4, we are having a 2" base coat of coarse aggregate bituminous mix (blacktop) laid and compacted, followed by 1-1/2" of fine aggregate material.