Some roads are attempting to take waste plastic and use it in place of other parts in the aggregate for asphalt.

https://en.wikipedia.org/wiki/Plastic_road

> It is currently unknown how these aggregates will perform in the mid- to long-term, or what effect their degradation might have on surrounding ecosystems.

This... doesn't entirely sound like the best idea since wear on it as an aggregate part could contribute to microplastics.

https://www.orbia.com/this-is-orbia/news-and-stories/plastic...

> What does infrastructure look like in the future? How can we build more sustainable roads? How do we solve climate challenges, such as stormwater drainage? Two men from the Netherlands, Anne Koudstaal and Simon Jorritsma, suggested using plastic, and in 2013 they drew the first concept for a road made of recycled plastic.

https://www.asphaltpavement.org/expertise/engineering/plasti... (this is from an asphalt paving trade group... so take what it says with appropriate skepticism)

https://stateline.org/2022/12/12/plastic-roads-are-paved-wit... appears to reference the National Asphalt Pavement Association material also.

I'd like to think I was smart enough to think of roads made with recycled plastics, but I guess I was assuming that once bacteria attack plastics, then all hydrocarbon materials are pretty much in the firing line.