Right. Concrete. Here is something called Concrete Canvas, a double layer of tightly knit fabric with cement powder between. It is flexible, light (5, 8 and 13mm thick), is put in place and then hosed down, forming a thin concrete skin.
It appears to be deployed all over the world for emergency shelters, ditches and water redirection, slope stabilisation and concrete repairs. Its military applications include reinforcing sandbags and bastions and laying down emergency hard surfaces. It comes in rolls; it seems magical. The emergency shelters could use some design attention.
They have a kit which includes an inflatable liner attached to a front gable door panel, which is inflated, draped with concrete canvas, watered and is ready in 24 hours. Other openings can be cut in after it is rigid. The strength is such that it can then be bermed.
I chose the image above from a vast array on the Concrete Canvas website because it is dramatic, but also shows the texture of the surface. Unfortunately the inside is lined with the plastic from the inflatable – shiny, maybe sweaty. Emergency shelter is the operative term. It would be very interesting to see just how far these shells could be adapted for permanent use.