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It seems like you at least need the following:

  1. A self-drilling wellhead to reach the subsurface water, storage tank
  2. Some process for refining the regolith into the optimal composition, storage tank
  3. A mechanism for composing the concrete into a structure.

To support all three, you need #4, a power source. I'm guessing probably an RTG. What I'm asking about here mostly is #2 - I don't know beans about concrete on either planet - what would be the process of collecting and processing that material, and what else have I overlooked here?

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    $\begingroup$ You need a pressure vessel, because the atmospheric pressure on Mars is just at or slightly below the triple point of water, so you're going to have a hard time maintaining liquid water with which to mix the concrete unless you can increase the ambient pressure. $\endgroup$ – Tristan Nov 29 '16 at 21:16
  • $\begingroup$ Other energy producing options might be solar concentrator with turbine or Sterling engine $\endgroup$ – Flanker Dec 5 '16 at 3:27
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Concrete is composed of Portland cement, water, and aggregate.

The manufacture of Portland cement is an energy and space intensive process. To wit:

The most common way to manufacture portland cement is through a dry method. The first step is to quarry the principal raw materials, mainly limestone, clay, and other materials. After quarrying the rock is crushed. This involves several stages. The first crushing reduces the rock to a maximum size of about 6 inches. The rock then goes to secondary crushers or hammer mills for reduction to about 3 inches or smaller.

The crushed rock is combined with other ingredients such as iron ore or fly ash and ground, mixed, and fed to a cement kiln.

The cement kiln heats all the ingredients to about 2,700 degrees Fahrenheit in huge cylindrical steel rotary kilns lined with special firebrick. Kilns are frequently as much as 12 feet in diameter—large enough to accommodate an automobile and longer in many instances than the height of a 40-story building. The large kilns are mounted with the axis inclined slightly from the horizontal.

The finely ground raw material or the slurry is fed into the higher end. At the lower end is a roaring blast of flame, produced by precisely controlled burning of powdered coal, oil, alternative fuels, or gas under forced draft.

As the material moves through the kiln, certain elements are driven off in the form of gases. The remaining elements unite to form a new substance called clinker. Clinker comes out of the kiln as grey balls, about the size of marbles.

Clinker is discharged red-hot from the lower end of the kiln and generally is brought down to handling temperature in various types of coolers. The heated air from the coolers is returned to the kilns, a process that saves fuel and increases burning efficiency.

After the clinker is cooled, cement plants grind it and mix it with small amounts of gypsum and limestone. Cement is so fine that 1 pound of cement contains 150 billion grains. The cement is now ready for transport to ready-mix concrete companies to be used in a variety of construction projects.

from here

It seems unlikely that limestone and clay are available on Mars, not to mention the huge facilities.

Probably best to come up with a different substance to build your colony out of.

Note: experiments have been done on making cement from lunar soil simulants. The process of producing the cement is apparently the same though, although it has only been carried out on a tiny scale.

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    $\begingroup$ He probably doesn't literally mean concrete but marscrete, which does not have the same ingredients. I think we were supposed to pick up that it wasn't literal concrete from the context. $\endgroup$ – called2voyage Nov 29 '16 at 21:29
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    $\begingroup$ Interesting stuff, but what you're overlooking is WHY those kilns and facilities are so large - economies of scale. I suspect that you could have a pizza-oven sized kiln, as long as you're willing to accept that your output is going to be a small fraction of what a proper Earth facility produces. @called2voyage is right, but this is still good stuff. $\endgroup$ – Chris B. Behrens Nov 29 '16 at 21:34

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