Transportation departments learned long ago that sealing the cracks in
asphalt pavements prolongs the life of the pavement.

Years ago they used solvent based asphalt materials to seal the cracks but
most have now switched to emulsified asphalt materials (the so-called water
based asphalt sealers). Some use hot-applied asphalt. The emulsified
asphalt isn't particularly better than solvent based but eliminates most of
the solvents that evaporate to the atmosphere. Some use crack sealers that
contain polymer modified asphalt to give the asphalt more elasticity to help
prevent the cracks from reforming. Sand or sawdust is cast over the freshly
place crack sealer to prevent tracking from foot or vehicle traffic.

Without a good, stable base and sufficient asphalt pavement thickness, no
amount of crack sealing is going to make up for the deficiency.

Harry

"Walter Cohen" wrote in message
...
I'm sure this has been debated before......

I have an aging asphalt (black top) driveway and I am thinking of coating
it with driveway sealer (whether by myself or hire someone to do it).
Does this really do anything for the driveway other than make it look
cosmetically more appealing and perhaps fill in any small/minor cracks?
It would seem that this would only be more cosmetic than anything else.
The need would arise maybe 2-3 years down the road to do it again, or have
the driveway repaved.
The brands/types I've seen appear to all be basically the same, lasting
anywhere from 2 to 5 years. Some have a sand mix supposedly helping the
dried surface be a bit more coarse an making the surface not as slipper on
rain/snow for tracktion. And why are they all called 'airport grade'?

Thoughts?
Thanks,
Wally