I’ve wondered if that were possible. It seems that mixing a petroleum based plastic into the asphalt would be a no-brainer.
They've also mixed ground-up tires in asphalt mix.
Some tests have shown that it increased the life of the road surface, decreased rolling resistance of the pavement and made the initial surfacing of the road much easier.
Haven't heard much about it, lately.
Somebody with a lobby is probably against it...so...there ya go.
If it makes the road last longer, then I'm sure all the contracted paving companies would be against it.