Sean Weaver, president of TechniSoil Industrial in the northern California city of Redding, says the polymer-infused roads churned out by the company’s pavement process are sturdier, flatter, safer and more durable than those made with regular asphalt.

More appealing to environmentalists, they incorporate 100% of the old asphalt — sparing the air from dozens of trips by trucks hauling away and bringing in building material — and provide a new market for plastic products that could otherwise wind up in a landfill.