On 8/30/2010 1:31 PM, Joe wrote:
On Aug 30, 12:06 pm, Steve wrote:
On 8/30/2010 11:46 AM, Bob wrote:





Hello,

Was just wondering about this.

It is pretty well accepted, apparently, that a new asphalt driveway for
a residence should be laid over about 4" to 6" of gravel.
Never over soil directly.

Why ?

The hot, liquid, asphalt I would pretty much think makes the gravel into
one, solid, "clump" underneath (the asphalt).
So, it's hard to see that any improved drainage results.

Increased "stability" perhaps ? If so, how ?

So what does the gravel add as a benefit over just laying the asphalt
on top of well compacted soil ?

Thanks,
Bob

A: asphalt pavement is not liquid
B: the gravel is for drainagek and stability.

snip

Steve's right...you're confusing paving asphalt (contains a lot of
gravel aggregate) and roofing asphalt (contains minor amounts of finer
fillers). Next time you drive by a highway surfacing project note the
big dump body trucks lined up there filled with hot mix. No liquids
there.

Joe

The liquid, sticky, or plastic part (asphalt cement) is only 5% of the
total mix. The rest is aggregate.