Mars Colony Cement & Concrete

JoshNH4H · 2012-03-15 16:30:43

GW- Rail transport is a very interesting topic and we actually have a dedicated thread for it. I've quoted your post there and responded

Edit: The railroad thread is here

Last edited by JoshNH4H (2012-03-15 18:33:42)

John Creighton · 2012-03-15 18:03:46

GW Johnson wrote:

Not sure what a railroad might look like on Mars, given that steel will not be generally available for a long time after the first bases are established, except as an expensive import.

I’m not sure that’s true. If you have a good enough ore isn’t a hot fire enough to separate the metal? Anyway, I agree that it won’t be produced in large quantities early on and probably mostly used to make tools.

GW Johnson · 2012-03-15 19:11:15

Well, steelmaking is a little more complicated than just a hot fire. Although that is exactly how one makes small wrought iron nodules: in a campfire with decent ore and a positive air blast.

Once made, these nuggets can be forged together into a useful-sized ingot, for fashioning various items, but it's still wrought iron. Very high in both carbon content (like cast iron) and slag inclusions (which make it easily formable, hence the name "wrought").

To make real steel, you have to remelt a big pot of this stuff (about 3000 F, 1650 C), then blow oxygen through the puddle, to burn out the carbon to just the right trace amount for steel. The slag floats to the top as a thick layer, rather like the scum floating on overheated hot chocolate. Then, you decant the steel through the bottom, out from under the slag layer, and cast it into ingots (usually about half the size of a diesel submarine battery cell).

Cast steel still has lousy properties, variable all through the ingot. You have to reheat it to just below melting (about 2800 F, 1540 C), and forge it, usually with repeated hammer blows and roller-forming operations, both measured in multiple tons for a typical ingot. This operation produces the typical shapes coming from the steel mill as product, and these shapes have the structural properties we are used to (for mild steel around 36 ksi yield, 80-100 ksi ultimate, in tensile, with a Young's modulus near 30,000 ksi, and a Poisson's ratio near 0.3).

The alloy steels are made similarly, they just add things like nickel and vanadium in the initial melt after carbon burnout. Some of these are heat-treatable after manufacture to very high strengths, others (like 300-series stainless) are not.

To make these materials in industrial quantities requires a pretty big plant. It did in a relative sense, even 300 years ago, when railroads were first attempted here on Earth. Cast irons and wrought irons were usually just not suitable for rails and boilers. It took real steel, just like that used in sword- and gun-making, only just a whopping lot of it. Ship-building did a lot better by the beginning of the 20th century, once steel became available in 10,000 ton+ quantities.

How one would do all this on Mars, I dunno. Certainly not in some analog to a campfire, or even in an analog to a 17th century puddling furnace. But it certainly needs to be done, especially once we start planting bases.

GW

JoshNH4H · 2012-03-16 20:10:32

GW- We had a thread on Iron and Steel before the crash, but it seems to have been lost. Since it's such an important topic, I'll make a new thread (By the way, if there's ever a topic that you want to discuss but there isn't a thread for, you can always make your own thread for it).

louis · 2012-03-16 22:51:32

GW Johnson wrote:

Well, steelmaking is a little more complicated than just a hot fire. Although that is exactly how one makes small wrought iron nodules: in a campfire with decent ore and a positive air blast.
Once made, these nuggets can be forged together into a useful-sized ingot, for fashioning various items, but it's still wrought iron. Very high in both carbon content (like cast iron) and slag inclusions (which make it easily formable, hence the name "wrought").
To make real steel, you have to remelt a big pot of this stuff (about 3000 F, 1650 C), then blow oxygen through the puddle, to burn out the carbon to just the right trace amount for steel. The slag floats to the top as a thick layer, rather like the scum floating on overheated hot chocolate. Then, you decant the steel through the bottom, out from under the slag layer, and cast it into ingots (usually about half the size of a diesel submarine battery cell).
Cast steel still has lousy properties, variable all through the ingot. You have to reheat it to just below melting (about 2800 F, 1540 C), and forge it, usually with repeated hammer blows and roller-forming operations, both measured in multiple tons for a typical ingot. This operation produces the typical shapes coming from the steel mill as product, and these shapes have the structural properties we are used to (for mild steel around 36 ksi yield, 80-100 ksi ultimate, in tensile, with a Young's modulus near 30,000 ksi, and a Poisson's ratio near 0.3).
The alloy steels are made similarly, they just add things like nickel and vanadium in the initial melt after carbon burnout. Some of these are heat-treatable after manufacture to very high strengths, others (like 300-series stainless) are not.
To make these materials in industrial quantities requires a pretty big plant. It did in a relative sense, even 300 years ago, when railroads were first attempted here on Earth. Cast irons and wrought irons were usually just not suitable for rails and boilers. It took real steel, just like that used in sword- and gun-making, only just a whopping lot of it. Ship-building did a lot better by the beginning of the 20th century, once steel became available in 10,000 ton+ quantities.
How one would do all this on Mars, I dunno. Certainly not in some analog to a campfire, or even in an analog to a 17th century puddling furnace. But it certainly needs to be done, especially once we start planting bases.
GW

A very light rail can still carry useful tonnages in trains of freight cars. A community on Mars is unlikely to exceed 10,000 humans for many decades and will be a very frugal community in its use of materials. Its steel needs will be pretty limited I would say. A very light automated railway would serve the uses of the community if a railway were necessary (doubtful I think - I would prefer land trains using cleared paths over firm ground.

I am sure with investment for ISRU in the hundreds of millions small scale, highly automated furnaces can be developed which will produce high quality steel in appropriate amounts - kgs rather than tonnes I think.

GW Johnson · 2012-03-18 16:14:27

I, too, am pretty sure it will start with the equivalent of truck rigs on graded roads. The problem is one of energy: each rig must be self-contained. I suspect they will carry liquid or liquified chemical fuels and oxidizers. A lot of effort and energy will go into this, even if the truck rigs are robotic.

Once steel is available, you can transport at a lot less effort and energy with an electric railroad powered by a centralized power station. The only problem is i^2R losses in the steel rails. You're going to need electric cables as part of the track, feeding power to the steel rails at intervals.

That means, in addition to an iron/steel industry, you're going to need either an aluminum or a copper industry, as well. Or both. Plus some way to make insulation sheathing or stand-off insulators for the cables. The plastic we use here will not be suitable in the harsh UV and radiation environment there.

I would suggest glass for the standoff insulators. That requires a source of silica.

My how required infrastructure multiplies! Multiplies? Exponentiates.

GW

JoshNH4H · 2012-03-18 21:07:45

I would say that we would probably be looking at Aluminium instead of Copper, since Aluminium also has other uses, plus is more common. I've had a post sitting in Open Office for a few weeks on Aluminium, so I'm hopefully going to finish that soon and then post it. Glass is going to find a lot of use in the colony anyway, since it will be needed for greenhouses. I don't think we'll be using electrified rails until somewhat later in the colonization effort, when we have in-situ nuclear power and thus cheap electrical energy, and more importantly very highly traveled train lines that make the cost-benefit for installing the equipment to electrify a railroad work.

Diversity of materials and components tends to diversify within any one system, but the real trick is to make each material and component do double, triple, or quadruple duty (or more!) so that the system can become self-supporting, with the possible exception of a very small number of low-mass, high complexity parts or materials imported from Earth, and paid for with goods or more likely services done in exchange by Martians.

GW Johnson · 2012-03-18 21:45:28

I'm with you about multiple duty. I, too, would go with aluminum, unless we just happen to find big copper deposits. Electrified rail is something we already know works quite well here on Earth. It used to be quite common, although diesel-electric has pretty much taken over, here at home.

It's all in the prospecting, something we've not yet programmed any robots to do.

GW

JoshNH4H · 2012-03-19 03:33:03

Big copper deposits would be great, since Aluminium production is likely to be very energy intensive as well as complicated. Even if we don't have a planet-wide map, or one for the specific area where we would sure be nice to have a sense of what resources are available, even in a general sense. By the way, I would suggest Cast Basalt as an alternative to Glass, just because the materials to make Cast Basalt are cheaper. Otherwise, I would expect the Cast Basalt and Glass industries would mostly parallel each other.

Midoshi · 2012-03-19 21:36:57

Yes, you can expect copper emplaced as hydrothermal sulfide deposits on Mars. You would find veins in both large crater basins and volcanic regions. It would be accompanied by other "chalophile" elements, mostly lead and zinc, but also antimony, selenium, cadmium, arsenic, silver, gold, and tellurium.

If you want to read more about the potential mineral resources on Mars, I'd recommend the following paper (Mike West was nice enough to host it for those who can't get through paywalls):

Potential martian mineral resources: Mechanisms and terrestrial analogues (West & Clarke 2010)
Planetary and Space Science 58 (2010) 574–582
http://people.physics.anu.edu.au/~web11 … logues.pdf

P.S. I don't think I properly responded to GW's salutation earlier in the thread: Howdydoo and welcome back yourself, sir!

Last edited by Midoshi (2012-03-19 22:31:14)

JoshNH4H · 2012-03-21 01:13:59

Midoshi- That's a really fascinating paper. Actually, the only important ore which is notably missing, according to that report, is Bauxite. That is inconvenient and I would really hope that it would be possible to find some kind of usable Aluminium at elevated concentration. We don't necessarily need 100% bauxite, as long as the Bayer process (e.g., concentrating the Aluminium Oxide by immersion in a highly basic solution) can work. If we can find an ore that is mostly Iron and Aluminium oxides, we can smelt the Iron out and then get the Aluminium from it, though I don't know if this is an ore that actually exists in the real world. Copper is nice because it really reduces the energy we need to use on Aluminium production. For that matter, we could also conceivably use Copper (reinforced with Steel) for heat transfer. That leaves a need for Aluminium to make mirrors and perhaps as a chemical catalyst in a few applications. Don't get me wrong, these are absolutely vital for the colony. But they are extremely low mass, and this is good because it means that the cost to the colony from using simpler but less efficient methods of making Aluminium is not as high. When they start building rockets, things will be different, but that won't be for a fair amount of time.

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#51 2012-03-15 16:30:43

Re: Mars Colony Cement & Concrete

#52 2012-03-15 18:03:46

Re: Mars Colony Cement & Concrete

#53 2012-03-15 19:11:15

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#54 2012-03-16 20:10:32

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#55 2012-03-16 22:51:32

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#56 2012-03-18 16:14:27

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#57 2012-03-18 21:07:45

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#58 2012-03-18 21:45:28

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#59 2012-03-19 03:33:03

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#60 2012-03-19 21:36:57

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