[lhpz]

The interesting question would be to know if the mix of raw earth + additives necessary for 3D printing, can be reused for a new construction after 20 years.

The raw earth used for traditional building techniques like rammed earth, can be re-used just by adding some water after razing the earth walls, as long as no cement/lime additive was initially used. This is also the Achilles heel of these traditional techniques: moisture will destroy the structure of a rammed earth wall when not appropriately protected with a large roof + above the ground foundation to avoid capillary rise.