In article B0Fcg.958197$x96.218806@attbi_s72, HarryS says...

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

Of course that's all true.

As to periodic sealing, though, recall highway departments have the constraint
of needing to accomodate traffic nearly constantly whatever they do (aside from
a totally new road). So what they do or do not do may be quite different from
what a homeowner does or does not do with his driveway.

Banty


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