Not back to a plant: there are road resurfacing machines that tear up the existing surface, run it through a dirt and dust separator, recombine it with tar[1] a

Not back to a plant: there are road resurfacing machines that tear up the existing surface, run it through a dirt and dust separator, recombine it with tar[1] at temperature, and then put it right back down. Yes, there is thermal, chemical, and mechanical energy being used to do all of that but it's a fraction of resurfacing a cement-based road. [1] I'm not a road engineer so I'm not 100% sure what substance is used to stick the parts of the asphalt back together when it's put back down but it looks and smells like hot tar.