By value, I meant, broadly, engineering/environmental value, not financial. Its value as a material from an engineering perspective is that it (a) functions fan

By value, I meant, broadly, engineering/environmental value, not financial. Its value as a material from an engineering perspective is that it (a) functions fantastically in compression and with the addition of (usually) rebar, it can function in tension and bending as well, and (b) it is generally speaking easy and cheap to build structures (of all sorts) with it. This comes from a beautiful interaction of materials - cement, sand/aggregate, steel - all working in concert together. In fact, turning concrete into gravel on roads does precisely what you suggest is a bad thing (and which I agree is bad!) - pursing an economically valuable form of recycling which is less environmentally valuable than the significantly more challenging pathways towards proper structurally valuable reuse. All sorts of things can go into aggregate for roads: various forms of sand, stone, concrete, etc. anything you can make gravel out of really. If you can instead somehow reclaim the concrete and/or the cement within the concrete for structural use rather than use as aggregate, you can displace more carbon emissions by preventing the manufacture of new cement/concrete.