Worth pointing out that if you're patient with setting times, you can use portland cement substitutes (fly ash, ground blast furnace slag) as a substitute for p

Worth pointing out that if you're patient with setting times, you can use portland cement substitutes (fly ash, ground blast furnace slag) as a substitute for portland cement. Slower strength times (several days longer) but same long term strength and way lower embodied carbon. The thing i ponder about this is the foundations needed for a setup. Concrete stacks very well (think dams) but you need very strong foundations for tall, solid concrete structures.