Hi Bill
16 Apr 98, Bill Wunsch writes to Rick Nolan:
 > I commented to a friend that they should use
 > the concrete for a firm base and a smooth layer of asphalt over top.
 > He replied that wouldn't work, because the asphalt would not stick
 > properly to the contrete surface.  He commented that the contrete
 > surfaces on highway bridges in this province are not covered with
 > asphalt for that reason. That startled me a bit, since I have a
 > concrete driveway that had the surface totally eaten away by the
 > action of freezing water, and a two inch layer of asphalt on top has
 > stood up well for years.  But then there is slightly less traffic on
 > my driveway than on the highway.
Yse its definately heavy traffic volume that does it,especially in
the summer with 30C+ heat and 40 ton + trucks ;-( and then the winter
freezes finish it off.
> Meanwhile, back at the airport, if I remember correctly from my flying
 > years, the runways seemed to be asphalt.  When new construction was
 > done, it was contrete.  And when the time came to improve the surface
 > (because the concrete had become uneven and was not a pleasure to land
 > on) it would be covered with a thick layer of ashpalt.  It seems to
 > stick there, but that may be only because a very thick layer is used,
 > not just a thin two inch cap.
A new main runway was laid here about 5 years ago (about 12000 feet if
I remember correctly) which was all asphalt over a deep bed of crushed
ballast and it seems to have stood up very well.
Regards,
Rick
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