On 6/25/2010 3:41 PM, l, not -l wrote:
> On 25-Jun-2010, Kate > wrote:
>
>> Sound like something on the menu at your local
>> pub?
>>
>> That's what comes to my mind every time I see these
>> signs along the roads here in the Pittsburgh countryside.
>> Maybe pita chips and seasoned olive oil?
>>
>> No, it's a weird local (as far as I know) phenomenon
>> where in the summer many of the back roads sport these
>> signs. It means the county (or whoever is in charge of
>> these roads) is going to put gravel chips and oil on the
>> roads. I guess it's supposed to do something to keep
>> them in good repair, but I've always found it odd.
>
> The process is called sealcoating and is used to extend the life of asphalt
> pavement. The idea is to fill cracks and voids with a tar-like substance
> and small gravel. In climates subject to freezing, one of the major
> destroyers of pavement is ice. Water fills cracks in the asphalt paving,
> then expands as it freezes make the crack bigger and pushing up the
> surrounding pavement; freeze/thaw cycles breakdown the paving until potholes
> form and traffic hitting the hole edges does even more damage.
>
> Sealcoating fills the cracks with aslphalt and gravel, reducing or
> eliminating the damage of freeze/thaw cycles. If it is being done in
> places not subject to freeze/thaw, I have no idea why they would do it.
>
>

They seem to have abandoned that method in my state. Now they seal the
cracks only. They have a large trailer mounted tank filled with the
sealant and there is a hose and wand that the operator uses. I suspect
this uses a lot less material and you aren't dinging windshields and
blasting the paint off cars.