Cutting 20 feet asphalt driveway

Back in the day when I used to put up vinyl siding, I found that the best way to cut it with a circular saw was with a cheap 140 tooth plywood blade installed backwards (to give the teeth a negative rake and prevent chipping):

For really hard plastics, I've used a diamond abrasive blade before and that did a great job (these are incredibly expensive if we're talking about a single cut though). I would imagine an abrasive blade for cutting metal would do just as well though:

You should be able to pick up either of these for less than $5.

Wear good safety glasses and do a trial cut first with whatever option you go with - plastic will chip long before it will bind the blade in most cases, and these can be both sharp and high velocity.

If you can find the same size arbor (hole in the blade) it works great. A thin blade uses less horsepower but won’t last as long. Make sure to blow the dust out of the motor after done as it will shorten the motor life if left in the motor. I do this with a table saw and skill saw for brick and cinder blocks when I want a clean cut. Also wear a dust mask you dont want to breathe the dust.