Earthbags for Mars Colonies

NASA recently announce a competition to develop means of using in-situ materials on the Moon or
Mars to build structures.

NASA suggests, and no doubt most people will pursue, using adhesives mixed with regolith or some type of sintering in order to create the structural elements needed. Both of these methods are non-optimal.

Sintering is a highly energy intensive process. Considering that large nuclear reactors will not be sent to Mars sintering is not a means of creating structures quickly or efficiently. They my look nice and the technology is fascinating and eventually viable it will not be until space power-source capabilities increased significantly.

Adhesives are a simpler process. But they still rely on chemistry which has to be extensively explored. The temperature, atmospheric composition, and even wind could limit the viability adhesive chemical reactions on Mars. So to attempt to create a type of concrete or glue I would not consider reliable.

With adhesives there is also a high material weight cost for transport. It is unlikely that everything needed to make beams and bricks using adhesives or additives will exist on Mars. Tanks of chemicals will have to be transported and safely landed on Mars. Unless again high energy requirement systems are feasible.

The solution much be mechanically self-reinforcing. An igloo or a geodetic dome.

What the most basic level every mineral on Mars is dirt. Particles which, when compressed become essentially solid. The method I decided to pursue was the used of sandbags.

Sand bags require minimal transported material in order to create high volume constructive elements. And bags can be changed to tubes. A single polypropylene tube could be filled with martian dust and behave like a 3-D printer creating a beehive-like igloo structure. A Martian Coil-Pot Hut.

Initially I thought that the bags would have to be specially designed to insure that during settling the sand within the bags would not be able to  cause bulges or gaps which would cause a structure to fail. But as I did my research I found earth-bag structures.

Earth-bag structures are exactly what I was imagining with my sandbag concept. Bags are filled, compressed, and then stacked. These structures are generally igloo shaped but can take square form.

With more research I found several structural analysis dissertation papers on earth-bags which justified their structural integrity.

The benefits of such structures on Mars is that they can be built by hand without complex machinery. But in order to prepare ahead of time, a large 3-D printer-like system could be delivered to build the huts.

The huts have a high thermal mass so they will not require large amounts of energy to heat. This mass of soil also serves as radiation protection. And since they are using large quantities of dirt the huts can have a basement increasing the total volume of the structure.

Earth-bag, or in this case, Mars-bag structures are an efficient and almost optimal solution for preliminary buildings on Mars using in-situ materials.

Note: Since the primary challenge with earth-bags is that fact that the sand or soil inside of them can shift, they would actually be even more optimal on the moon where the regolith is un-eroded and therefore will have a higher shear resistance, that is sliding over itself inside of the bag.