Our teacher gave us a project before Christmas break, it was to build a miniature house, she didn't state what specific materials should be used, so I built a cardboard house. She didn't accept it because it wasn't firm enough for her. Now I want to know if it is possible to build a miniature concrete house? Considering I can't find any tutorials online I'm guessing it has a high chance of collapsing, but I don't know, that's why I came here.
Concrete isn't a good material for such a small model. I would suggest foamboard. You can get it at craft stores. If you can't find half inch thick material, laminate two layers of quarter inch board. Architects use foamboard all the time. You can glue it with Elmers. If you really need heavier duty stuff, there is concrete wall board used in bathrooms. You can get it at stores like Home Depot. Much harder to cut and work with.
If you must use concrete, you could consider ShapeCrete -- it's a clay-like moldable concrete, more info could be found on their web site www.shapecrete.com . They also have a projects gallery that you can use to decide whether this material will suite your needs. It is available from Amazon.