I have never seen an autonomously built concrete house, but building with ICF forms is basically like stacking giant Styrofoam legos, and the pouring concrete in the middle. And insulation values of R40 are common! There was an interesting blog series to follow from Ana White about building an ICF home in Alaska for their moms.

http://www.ana-white.com/2013/03/momplex/building-momplex-ic...