10 ms·

Engineers Investigate a Simple, No-Bake Recipe to Make Bricks from Martian Soil

107 points by jameslk 10y ago

mparlane 10y ago
Sounds similar to rammed earth construction? https://en.wikipedia.org/wiki/Rammed_earth https://en.wikipedia.org/wiki/Rammed_earth
- mirimir 10y ago
  Yes, this is rammed earth. Styling it as a discovery seems strange. Also strange: > Researchers also investigated the bricks’ strengths and found that even without rebar, they are stronger than steel-reinforced concrete. That's under compression, I'm sure.
  - peterwwillis 10y ago
    No! Flexural strength of 50MPa!!! And rammed earth only has a compressive strength of 4.3MPa! Concrete has a flexural strength of around 30MPa, and I don't know math so I don't know what the reinforced concrete is like, but this is still stronger than even cooked bricks. Here's the source publication: https://www.nature.com/articles/s41598-017-01157-w https://www.nature.com/articles/s41598-017-01157-w It looks like because of the composition of the martian soil they figured this would never work without a bonding agent and that it would require heating, and then somebody tried it anyway, and it worked. But here's the neat takeaway: The method they used to form it, along with particle size, and whacking it versus slowly loading it, significantly strengthened the resulting bricks. Nobody expected these things to happen, it seems. From article: "Loading rates were either quasi-static [..] or impact [..]. The lateral boundary condition of compaction loading was either rigid (confined by a steel wall), free, or flexible (confined by an elastomeric wall)" "Compacted Mars-1a solids were cut into beams and subjected to three-point bending tests" "It is remarkable that the lateral boundary condition of compaction loading significantly influences the strength and the shape of the compacted solid, specifically, the thickness-to-diameter ratio. Compared with the boundary condition, the effect of loading rate is secondary." "With the rigid boundary condition, the compacted Mars-1a samples are structurally integral but the flexural strength is relatively low, comparable with ordinary clay bricks. When the lateral boundary is free or flexible, R is nearly 3 times higher than that of rigid boundary condition. Between the free and flexible boundary conditions, the flexible boundary condition reached high R at much lower Pmax and the resultant solid thickness was only slightly smaller than that of the rigid boundary condition, much larger than that of the free boundary condition. The strength-wise efficacy of forming inside a flexible boundary is ~150–200% greater than the free boundary for R ~30 MPa, taking into consideration the flexible boundary’s larger sample sizes." -- Concrete alone has a shitty tensile strength, compared to its compressive strength. If you add steel cables to the concrete, the hybrid material's tensile strength increases. Similarly, Cod is what you get when you add natural fibers and other material to rammed earth. Its tensile strength is also significantly higher due to the addition of the fibers. So then my next question is: could they bring along some cheap fibers (like mylar?) to strengthen these Mars-1a bricks even more? Maybe the way the materials are forming now, they don't need added tensile strength, or the fibers could interrupt the formation somehow. But it's worth trying...
    - mirimir 10y ago
      Impressive! Thanks for the paper link. The impact of flexible/free boundary condition is very interesting. It points to a key role for shear during compaction. Maybe grains rolling and locking? For fibers, I wonder if asbestos would be available. Maybe too hazardous. Edit: From the paper: > With the flexible boundary condition, the particle motion is localized. Clearly, during compaction it is critical to allow rotation and transverse motion of Mars-1a particles, so as to maximize the effective contact area and to promote bond formation. Excessive particle motion, however, may introduce defects, which explains why the free boundary compensates with higher pressure to achieve similar R as the flexible boundary. This is very cool. Martian regolith seems ideal for rammed earth construction.
      - adrianN 10y ago
        I wonder how uniform Martian soil is. We have explored only a tiny fraction of the surface with actual robots. On Earth there is a huge variation between different regions. I would expect it to be similar on Mars.
        jccooper 10y ago
        Martian regolith is believed to be fairly uniform across the planet, and this is backed by analysis at several widely-scattered locations. The dust is definitely well-mixed, but coarser parts are mostly of local origin and can vary, but because of the lack of biological elements are much less varied than on Earth.
    - pjc50 10y ago
      This is making me wonder if it might be a viable/useful construction technique on Earth, depending on how hard it is to make the Martian soil simulant.
      - LoSboccacc 10y ago
        https://en.wikipedia.org/wiki/Adobe https://en.wikipedia.org/wiki/Adobe (mudbrick with straw as structural reinforcement) it already is, it was also similarly used for reinforcing statue casts (with hairs iirc)
- drzaiusapelord 10y ago
  >Historically, additives such as lime or animal blood were used to stabilize it, while modern construction adds lime, cement, or asphalt emulsions. Curious to know what filler material is practical on Mars. I suspect animal blood is out of the question, unless of course, we consider the human settlers. I can see some potential for an amusing modern-day Modest Proposal with the problem of colonizing Mars.
endianswap 10y ago
"The amount of pressure needed for a small sample is roughly the equivalent of someone dropping 10-lb hammer from a height of one meter, Qiao said." On Earth or with Mars's gravity?
- dotancohen 10y ago
  And are those metric lbs or imperial meters? That sentence is quite the example of unit confusion!
- averagewall 10y ago
  I initially thought that too but realized it was a meaningless concern. Even if you knew g, it wouldn't help because the pressure also depends on the thickness of soil it's landing on, as well as its mechanical properties - like how much it's already been compressed. A hammer dropped onto concrete exerts more pressure than it does dropped onto sand. Also, what's the shape of the footprint of the hammer? Error in that will be more than the difference between Earth and Mars gravity.
  - peterwwillis 10y ago
    See comments below for the link to their paper in Nature. Most relevant test case is "Impact test, Flexible boundary condition", where they give all the data on their test methodology. If you load Supplementary Data, Figure S9[1], it shows 400MPa at 1ms. It also shows (for the above test) around 9mm displacement at what looks like 365MPa? I suck at math so I'll let someone else figure out the force. [1] https://static-content.springer.com/esm/art%3A10.1038%2Fs41598-017-01157-w/MediaObjects/41598_2017_1157_MOESM1_ESM.pdf https://static-content.springer.com/esm/art%3A10.1038%2Fs415...
- tyingq 10y ago
  Wouldn't they just use a hand operated mechanical press though? Add hydraulics if you need more pressure. Something like this thing: https://www.youtube.com/watch?v=v7rgjxHP-yA https://www.youtube.com/watch?v=v7rgjxHP-yA with whatever adjustments for the mold and needed pressure.
sillysaurus3 10y ago
It would be really tempting to go settle Mars. Just... Leave everything behind, and go. I don't know why. Long-term survival seems unlikely for the first batch of colonists. It's almost inevitable that there will be some sort of disaster. And even if not, you'd have to live underground to avoid the radiation. Ever want to go for a walk? Not so easy on mars. Surely you'd start to feel caged after just a few weeks. Because you are. And yet I can't get it out of my head how tempting it would be. Why? Is it genetic? I've heard that one reason neanderthals died out is they would migrate until running into an obstacle, like the ocean, and then settle there on their perfectly-good land. The net result was that neanderthals stopped expanding. Whereas we did things that didn't make sense: launch ourselves into the sea, for example. And now we want to launch ourselves into the vast nothingness of literally-nothing, to go live as moles in a confined area, possibly without most of the amenities we take for granted. Yet I think I would. I just wish I could figure out why. Part of it is a longing for community. Life sometimes seems so pre-packaged. It's an awesome life, to be sure, and in the society you're reading this comment in, you probably have a lot of power to affect your life. You could get rich. Or you could move to a new country, or decide what career you want. But it's all been done before. And I think Mars is an escape hatch from that. There, the frontier exists. Even if it's the life of a mole in a cage, it's a cage nobody has ever dared to build before. And that's exciting.
- averagewall 10y ago
  It might be a sense of contributing to development of your society. Every brick you make is a significant visible improvement for everyone there. But on Earth, a lifetime's work is nothing compared to the whole world's output. You can't see if you're improving things, making things worse, or having no effect at all. If you do simple things like make bricks on Earth, they probably have negative value - somebody will have to do more work to break or discard them soon enough.
- methodin 10y ago
  We are, by nature, gluttons and that gluttony is insatiable in whatever infinite forms it takes (expansion, desire, fame, being the first, etc...) Explains pretty much our entire history.
- 10y ago
pacaro 10y ago
Some surprising materials have this property, including aspirin which can be formed into tablets with no other ingredients.
ahmeni 10y ago
This seems like one of those things that you'd really want as a plan A but absolutely require sensible plan B as a backup.
- emilyfm 10y ago
  Plan A would be to send some robots to try building using this technique. If it doesn't work, you're only out a few robots (who may be able to be repurposed). If it does work, leave them to it building a habitat which can be fitted out by further waves of robots later. By time that's all done the hard part of sending humans there will be more possible, and they'll have a base ready to move into.
  - jsymolon 10y ago
    Wall-e unit for compressing blocks and leaving a heap.
chiph 10y ago
If they can make them into interlocking Lego-style blocks, creating cut & cover tunnels is pretty easy. https://www.youtube.com/watch?v=LoRIztYmWjY https://www.youtube.com/watch?v=LoRIztYmWjY
mod 10y ago
You can do this on earth, with more pressure. https://en.wikipedia.org/wiki/Compressed_earth_block https://en.wikipedia.org/wiki/Compressed_earth_block http://www.dirtcheapbuilder.com/Home_Building/Earth_Block_Construction.htm http://www.dirtcheapbuilder.com/Home_Building/Earth_Block_Co...
- peterwwillis 10y ago
  Neat! But fwiw, the Martian bricks are up to 50 times stronger :3
tantalor 10y ago
> Digitally reconstructed brick Huh?
cpete 10y ago
Here's what The Onion, ahem, American voices have to say about it: http://www.theonion.com/americanvoices/scientists-constructing-bricks-simulated-martian-s-55890 http://www.theonion.com/americanvoices/scientists-constructi...

107 points by jameslk 10y ago

Sounds similar to rammed earth construction? https://en.wikipedia.org/wiki/Rammed_earth https://en.wikipedia.org/wiki/Rammed_earth

mirimir 10y ago
Yes, this is rammed earth. Styling it as a discovery seems strange. Also strange: > Researchers also investigated the bricks’ strengths and found that even without rebar, they are stronger than steel-reinforced concrete. That's under compression, I'm sure.
- peterwwillis 10y ago
  No! Flexural strength of 50MPa!!! And rammed earth only has a compressive strength of 4.3MPa! Concrete has a flexural strength of around 30MPa, and I don't know math so I don't know what the reinforced concrete is like, but this is still stronger than even cooked bricks. Here's the source publication: https://www.nature.com/articles/s41598-017-01157-w https://www.nature.com/articles/s41598-017-01157-w It looks like because of the composition of the martian soil they figured this would never work without a bonding agent and that it would require heating, and then somebody tried it anyway, and it worked. But here's the neat takeaway: The method they used to form it, along with particle size, and whacking it versus slowly loading it, significantly strengthened the resulting bricks. Nobody expected these things to happen, it seems. From article: "Loading rates were either quasi-static [..] or impact [..]. The lateral boundary condition of compaction loading was either rigid (confined by a steel wall), free, or flexible (confined by an elastomeric wall)" "Compacted Mars-1a solids were cut into beams and subjected to three-point bending tests" "It is remarkable that the lateral boundary condition of compaction loading significantly influences the strength and the shape of the compacted solid, specifically, the thickness-to-diameter ratio. Compared with the boundary condition, the effect of loading rate is secondary." "With the rigid boundary condition, the compacted Mars-1a samples are structurally integral but the flexural strength is relatively low, comparable with ordinary clay bricks. When the lateral boundary is free or flexible, R is nearly 3 times higher than that of rigid boundary condition. Between the free and flexible boundary conditions, the flexible boundary condition reached high R at much lower Pmax and the resultant solid thickness was only slightly smaller than that of the rigid boundary condition, much larger than that of the free boundary condition. The strength-wise efficacy of forming inside a flexible boundary is ~150–200% greater than the free boundary for R ~30 MPa, taking into consideration the flexible boundary’s larger sample sizes." -- Concrete alone has a shitty tensile strength, compared to its compressive strength. If you add steel cables to the concrete, the hybrid material's tensile strength increases. Similarly, Cod is what you get when you add natural fibers and other material to rammed earth. Its tensile strength is also significantly higher due to the addition of the fibers. So then my next question is: could they bring along some cheap fibers (like mylar?) to strengthen these Mars-1a bricks even more? Maybe the way the materials are forming now, they don't need added tensile strength, or the fibers could interrupt the formation somehow. But it's worth trying...
  - mirimir 10y ago
    Impressive! Thanks for the paper link. The impact of flexible/free boundary condition is very interesting. It points to a key role for shear during compaction. Maybe grains rolling and locking? For fibers, I wonder if asbestos would be available. Maybe too hazardous. Edit: From the paper: > With the flexible boundary condition, the particle motion is localized. Clearly, during compaction it is critical to allow rotation and transverse motion of Mars-1a particles, so as to maximize the effective contact area and to promote bond formation. Excessive particle motion, however, may introduce defects, which explains why the free boundary compensates with higher pressure to achieve similar R as the flexible boundary. This is very cool. Martian regolith seems ideal for rammed earth construction.
    - adrianN 10y ago
      I wonder how uniform Martian soil is. We have explored only a tiny fraction of the surface with actual robots. On Earth there is a huge variation between different regions. I would expect it to be similar on Mars.
      - jccooper 10y ago
        Martian regolith is believed to be fairly uniform across the planet, and this is backed by analysis at several widely-scattered locations. The dust is definitely well-mixed, but coarser parts are mostly of local origin and can vary, but because of the lack of biological elements are much less varied than on Earth.
  - pjc50 10y ago
    This is making me wonder if it might be a viable/useful construction technique on Earth, depending on how hard it is to make the Martian soil simulant.
    - LoSboccacc 10y ago
      https://en.wikipedia.org/wiki/Adobe https://en.wikipedia.org/wiki/Adobe (mudbrick with straw as structural reinforcement) it already is, it was also similarly used for reinforcing statue casts (with hairs iirc)
drzaiusapelord 10y ago
>Historically, additives such as lime or animal blood were used to stabilize it, while modern construction adds lime, cement, or asphalt emulsions. Curious to know what filler material is practical on Mars. I suspect animal blood is out of the question, unless of course, we consider the human settlers. I can see some potential for an amusing modern-day Modest Proposal with the problem of colonizing Mars.

endianswap 10y ago

"The amount of pressure needed for a small sample is roughly the equivalent of someone dropping 10-lb hammer from a height of one meter, Qiao said." On Earth or with Mars's gravity?

dotancohen 10y ago
And are those metric lbs or imperial meters? That sentence is quite the example of unit confusion!
averagewall 10y ago
I initially thought that too but realized it was a meaningless concern. Even if you knew g, it wouldn't help because the pressure also depends on the thickness of soil it's landing on, as well as its mechanical properties - like how much it's already been compressed. A hammer dropped onto concrete exerts more pressure than it does dropped onto sand. Also, what's the shape of the footprint of the hammer? Error in that will be more than the difference between Earth and Mars gravity.
- peterwwillis 10y ago
  See comments below for the link to their paper in Nature. Most relevant test case is "Impact test, Flexible boundary condition", where they give all the data on their test methodology. If you load Supplementary Data, Figure S9[1], it shows 400MPa at 1ms. It also shows (for the above test) around 9mm displacement at what looks like 365MPa? I suck at math so I'll let someone else figure out the force. [1] https://static-content.springer.com/esm/art%3A10.1038%2Fs41598-017-01157-w/MediaObjects/41598_2017_1157_MOESM1_ESM.pdf https://static-content.springer.com/esm/art%3A10.1038%2Fs415...
tyingq 10y ago
Wouldn't they just use a hand operated mechanical press though? Add hydraulics if you need more pressure. Something like this thing: https://www.youtube.com/watch?v=v7rgjxHP-yA https://www.youtube.com/watch?v=v7rgjxHP-yA with whatever adjustments for the mold and needed pressure.

sillysaurus3 10y ago

It would be really tempting to go settle Mars. Just... Leave everything behind, and go. I don't know why. Long-term survival seems unlikely for the first batch of colonists. It's almost inevitable that there will be some sort of disaster. And even if not, you'd have to live underground to avoid the radiation. Ever want to go for a walk? Not so easy on mars. Surely you'd start to feel caged after just a few weeks. Because you are. And yet I can't get it out of my head how tempting it would be. Why? Is it genetic? I've heard that one reason neanderthals died out is they would migrate until running into an obstacle, like the ocean, and then settle there on their perfectly-good land. The net result was that neanderthals stopped expanding. Whereas we did things that didn't make sense: launch ourselves into the sea, for example. And now we want to launch ourselves into the vast nothingness of literally-nothing, to go live as moles in a confined area, possibly without most of the amenities we take for granted. Yet I think I would. I just wish I could figure out why. Part of it is a longing for community. Life sometimes seems so pre-packaged. It's an awesome life, to be sure, and in the society you're reading this comment in, you probably have a lot of power to affect your life. You could get rich. Or you could move to a new country, or decide what career you want. But it's all been done before. And I think Mars is an escape hatch from that. There, the frontier exists. Even if it's the life of a mole in a cage, it's a cage nobody has ever dared to build before. And that's exciting.

averagewall 10y ago
It might be a sense of contributing to development of your society. Every brick you make is a significant visible improvement for everyone there. But on Earth, a lifetime's work is nothing compared to the whole world's output. You can't see if you're improving things, making things worse, or having no effect at all. If you do simple things like make bricks on Earth, they probably have negative value - somebody will have to do more work to break or discard them soon enough.
methodin 10y ago
We are, by nature, gluttons and that gluttony is insatiable in whatever infinite forms it takes (expansion, desire, fame, being the first, etc...) Explains pretty much our entire history.
10y ago

pacaro 10y ago

Some surprising materials have this property, including aspirin which can be formed into tablets with no other ingredients.

ahmeni 10y ago

This seems like one of those things that you'd really want as a plan A but absolutely require sensible plan B as a backup.

emilyfm 10y ago
Plan A would be to send some robots to try building using this technique. If it doesn't work, you're only out a few robots (who may be able to be repurposed). If it does work, leave them to it building a habitat which can be fitted out by further waves of robots later. By time that's all done the hard part of sending humans there will be more possible, and they'll have a base ready to move into.
- jsymolon 10y ago
  Wall-e unit for compressing blocks and leaving a heap.

chiph 10y ago

If they can make them into interlocking Lego-style blocks, creating cut & cover tunnels is pretty easy. https://www.youtube.com/watch?v=LoRIztYmWjY https://www.youtube.com/watch?v=LoRIztYmWjY

mod 10y ago

You can do this on earth, with more pressure. https://en.wikipedia.org/wiki/Compressed_earth_block https://en.wikipedia.org/wiki/Compressed_earth_block http://www.dirtcheapbuilder.com/Home_Building/Earth_Block_Construction.htm http://www.dirtcheapbuilder.com/Home_Building/Earth_Block_Co...

peterwwillis 10y ago
Neat! But fwiw, the Martian bricks are up to 50 times stronger :3

tantalor 10y ago

> Digitally reconstructed brick Huh?

cpete 10y ago

Here's what The Onion, ahem, American voices have to say about it: http://www.theonion.com/americanvoices/scientists-constructing-bricks-simulated-martian-s-55890 http://www.theonion.com/americanvoices/scientists-constructi...