From Dust to Structures: A Guide to Crafting Concrete on Mars
"The Martian soil will be harvested and turned into raw construction materials to build the first colonies"
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Introduction: 3D Habitat Printers
3D printing is the chosen method for construction on Mars, as autonomous robot builders are the ones building the habitats and settlements before the arrival of humans. Building a base that is move-in ready.
The habitat 3D printers need a material to be fed through them in order to start printing and building. This material needs to have a uniform consistency and a uniform hardening time, and it must be able to build strong, lightweight dome buildings with thick walls.
The material must be thick enough to hold its shape but not so thick that it clogs the machine. It cannot dry too quickly or it will crack, but it needs to cure quickly enough so that the next layer can be printed on top.
All of these requirements must be met while operating in extreme temperature changes and requiring low energy and no water to produce – unlike concrete on Earth. Water is a precious resource on Mars, and any ice that is converted into water is a valuable resource that nations will fight over.
There are two types of raw materials on the surface of Mars that can be used to create this 3d printing construction material. There is the regolith, a pulverized dusty layer of top soil deposited by asteroid collisions, and there is basalt rock, which was formed when lava cooled and solidified.
Before they can be used for 3D printing habitats, the raw materials must first be cleaned of the harmful perchlorates. This is done by washing them with water.
1. Making Martian Concrete Using Soil, Rocks, and a Plant Glue
Regolith stabilization is the process of making the loose soil (the regolith) on Mars more solid. Regolith can be made up of a variety of materials, including rock, dust, and sand. Stabilizing regolith involves using a binder, a glue, to bind the loose soil together to form a solid material.
On Mars, this glue can be made in a number of ways, such as by growing plants like corn in aquaponic greenhouses and converting the plant sugars into a (biopolymer) glue. Another option is to make high-density polyethylene plastic from carbon dioxide in the atmosphere and hydrogen from ice water in the Martian soil.
The glue is then mixed with Martian soil and basalt rock to give it strength. The resulting material can be fed into a 3D printer, heated up, and extruded, solidifying into a construction material. This building material is recyclable and is an effective insulator.
To make use of this construction process, the construction site needs to be located near areas on Mars with concentrated deposits of volcanic basalt rock, which can be found under the loose Martian soil.
2. Making Martian Clay Bricks
A clay-like sedimentary type of soil can be found on Mars in the ancient dried-up oceans. This soil has undergone weathering due to its exposure to water in the past.
The layers of clay naturally align under high pressure, allowing electrostatic forces to hold them together. By slowly squeezing and compressing the dry clay layers together, a solid geopolymer brick is formed - one that is able to withstand rocket blasts.
3. Turning Martian Sulfur into Concrete
Mars has sulfur in its soil, and this can be harvested to create a type of Martian concrete.
The sulfur needs to be heated to a liquid state at around 240°C/464°F and mixed with Martian soil in a 50/50 ratio. The resulting concrete has a compressive strength that is twice as high as that of Earth concrete and hardens quickly, making it ideal for 3D printing. It can also be remelted and recycled for reuse as habitats and structures on Mars evolve.
However, this means that the sulfur concrete is not heat resistant and needs to be encased in a fireproof material for protection. It also requires reinforcing, similar to how concrete on Earth uses metal rebar as reinforcement, and may need a coating to contain its strong smell.
4. Lasers and Microwaves (Advanced Martian Concrete Tech)
It is possible to skip the polymer/glue step by using more advanced methods, such as lasers or a microwave system, to heat and compress the soil until it becomes solid.
To do this, the Martian soil is put into a container and heated using an electric furnace or laser, causing the particles to fuse together and form a ceramic-like structure. This process is called sintering and requires a lot of energy.
But the explosive birth of nuclear fusion on Earth, traded and exported to Mars, will make it possible to sinter the regolith, and even begin extracting metals from the Martian soil.
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