The Crane WASP, also known as "the infinity 3D printer," uses locally sourced clay, mud or cement to 3D-print affordable homes. It can even use agricultural waste as aggregate. The system is now being used to build much-needed housing in Colombia.
Yup, it needs to dry fast enough for the next layer, but not so fast it makes a clog, and it needs to flow in just the right way you can predictably extrude a layer on. And be cheap-ish.
Of course, you still have to add a lot of non-structural components, like the other user said, and if it needs to take significant loads you also need to add reinforcement somehow, since concrete is weak under tension.
From what I’ve ready, the concrete recipe is the hard part.
Yup, it needs to dry fast enough for the next layer, but not so fast it makes a clog, and it needs to flow in just the right way you can predictably extrude a layer on. And be cheap-ish.
Of course, you still have to add a lot of non-structural components, like the other user said, and if it needs to take significant loads you also need to add reinforcement somehow, since concrete is weak under tension.
You also need to add insulation and then do something to hide the ugly layer lines.