from the geopolymers-for-exo-geo-locations dept.
Sustained space exploration will require infrastructure that doesn't currently exist: buildings, housing, rocket landing pads.
[...] "If we're going to live and work on another planet like Mars or the moon, we need to make concrete. But we can't take bags of concrete with us — we need to use local resources," said Norman Wagner, Unidel Robert L. Pigford Chair of Chemical and Biomolecular Engineering at the University of Delaware.
Researchers are exploring ways to use clay-like topsoil materials from the moon or Mars as the basis for extraterrestrial cement. To succeed will require a binder to glue the extraterrestrial starting materials together through chemistry. One requirement for this out-of-this-world construction material is that it must be durable enough for the vertical launch pads needed to protect man-made rockets from swirling rocks, dust and other debris during liftoff or landing. Most conventional construction materials, such as ordinary cement, are not suitable under space conditions.
UD's Wagner and colleagues are working on this problem and successfully converted simulated lunar and Martian soils into geopolymer cement, which is considered a good substitute for conventional cement. [...]
Geopolymers are inorganic polymers formed from aluminosilicate minerals found in common clays everywhere from Newark, Delaware's White Clay Creek to Africa. When mixed with a solvent that has a high pH, such as sodium silicate, the clay can be dissolved, freeing the aluminum and silicon inside to react with other materials and form new structures — like cement.
[...] The researchers mixed various simulated soils with sodium silicate then cast the geopolymer mixture into ice-cube-like molds and waited for the reaction to occur. After seven days, they measured each cube's size and weight, then crushed it to understand how the material behaves under load. Specifically, they wanted to know if slight differences in chemistry between simulated soils affected the material's strength.
"When a rocket takes off there's a lot of weight pushing down on the landing pad and the concrete needs to hold, so the material's compressive strength becomes an important metric," Wagner said. "At least on Earth, we were able to make materials in little cubes that had the compressive strength necessary to do the job."
Under vacuum, some of the material samples did form cement, while others were only partially successful. However, overall, the geopolymer cement's compressive strength decreased under vacuum, compared to geopolymer cubes cured at room temperature and pressure. This raises new considerations depending on the material's purpose.
"There's going to be a tradeoff between whether we need to cast these materials in a pressurized environment to ensure the reaction forms the strongest material or whether can we get away with forming them under vacuum, the normal environment on the moon or Mars, and achieve something that's good enough," said Mills, who earned her doctoral degree in chemical engineering at UD in May 2022 and now works at Dow Chemical Company.
Journal Reference:
Jennifer N.Mills, MariaKatzarova, and Norman J.Wagner, Comparison of lunar and Martian regolith simulant-based geopolymer cements formed by alkali-activation for in-situ resource utilization, Adv Sp Res, 69, 1, 2022. DOI: 10.1016/j.asr.2021.10.045
(Score: 2) by Username on Thursday August 18 2022, @04:18PM
When they send a rock crusher and cement truck to the moon.
They never will.
Can only hope Elon launches a tunnel boring machine along with a tesla when he retires on mars/moon. He's the only one that could accomplish anything close to a base.
(Score: 3, Interesting) by Runaway1956 on Thursday August 18 2022, @05:00PM (7 children)
The surface of Mars is NOT a vacuum. If they are considering Mars, they need something that will cure in Mars' low-pressure atmosphere.
Yeah, the moon is a vacuum, or near enough to it to make any argument pointless. Vacuum curing should work great on the moon.
As for pressurizing a slab, maybe all they need is to make a plastic bag big enough to fit into their forms. Mix the stuff up, and just pump it into the bag. Your launch pad needs to be 100 yards? Just have Glad garbage bag company fabricate a nice 100 yard baggie. Prepare the groundwork, erect whatever is going to be used for forms, spread your huge baggie out and smooth it, maybe put a little air into it, then start pumping. It would be awfully difficult to put a broom finish, or a hard trowel finish on the concrete. Then again, no one is likely to be walking barefoot on the nice new slab!
“I have become friends with many school shooters” - Tampon Tim Walz
(Score: 2) by Immerman on Thursday August 18 2022, @10:36PM (6 children)
>The surface of Mars is NOT a vacuum
It really is. It's not a hard vacuum like you'd find in deep space, but the surface pressure of Mars is 400-700 Pa - only a tiny fraction (about 0.5%) of Earths.
Keep in mind that vacuum is really just a measure of pressure relative to atmospheric pressure (normally Earth's). Suck out half the air from a box and it's at 50% vacuum (380mmHg at sea level), go to Mars and you've got a 99.5% vacuum
Earth at sea level = 1 atm = 0mmHg vacuum (as measured relative to Earth atmospheric pressure)
perfect vacuum = 0 atm = 760mmHg vacuum
Typical vacuum thermos = 0.001 atm = 759mmHg vacuum
Mars Vacuum = 0.0005 atm = 755mmHg vacuum
There's still some pressure there, you could even bring it down a little lower using a simple mechanical vacuum pump rather than the increasingly exotic ones needed to approach perfect vacuum, but for most practical purposes (not including trying to pass through it at hypersonic speeds like found in reentry) it's a rounding error.
(Score: 0) by Anonymous Coward on Friday August 19 2022, @01:38AM (3 children)
That's not how you measure vacuum. By that scale my car tires have negative 2 vacuum, and Venus has negative 60.
(Score: 2) by Immerman on Friday August 19 2022, @04:53AM (2 children)
Yes, if it weren't simply an undefined statement. And?
You can only measure vacuum relative to a reference point at higher pressure. It's just a name given to a negative relative pressure.
You can measure the quality of vacuum relative to the theoretical maximum - but then you're just measuring absolute pressure, and almost nobody cares outside of particle physics and simulating outer space environments.
When you get right down to it vacuum isn't really a thing - it's just the absence of pressure, like dark is the absence of light. You can measure how much darker one thing is than another, but nobody measures the absolute darkness of a thing.
(Score: 0) by Anonymous Coward on Saturday August 20 2022, @02:20PM (1 child)
No. A vacuum is defined as (effectively) zero pressure. It is a descriptor of a single point at the end of the scale. The scale itself measures pressure.
Saying something has 40% vacuum is as nonsensical as saying a point on a graph has 40% of the origin.
(Score: 2) by Immerman on Saturday August 20 2022, @02:48PM
That's one definition.
But vacuum is also something that can be measured [wikipedia.org], which implies a spectrum rather than a singular point.
See my reply to FatPhil a couple posts down for more detail, or read through the Wikipedia page - which starts at your position and then expands.
(Score: 2) by FatPhil on Friday August 19 2022, @07:09AM (1 child)
> It really is.
Let's take a moment to analyse that absurd statement...
> It's not a hard vacuum like you'd find in deep space, but the surface pressure of Mars is 400-700 Pa - only a tiny fraction (about 0.5%) of Earths.
Exactly, so NOT a vacuum. Thank you for that insightful analysis which absolutely destroys your original point. Landers use parachutes to land on it. Helicopters can even fly in it. The clues were all there.
> Keep in mind that vacuum is really just a measure of pressure relative to atmospheric pressure
It really is time for you to stop making scientific-looking statements.
Great minds discuss ideas; average minds discuss events; small minds discuss people; the smallest discuss themselves
(Score: 2) by Immerman on Friday August 19 2022, @02:58PM
Note that the phrase hard vacuum, which you immediately recognized, also implies the existence of other types of vacuum.
I think we are talking about different definitions of the word. You seem fixated on the theoretical ideal:
Which sometimes exists for brief moments in particular volumes of space, but isn't generally applicable even in the emptiest depths of the intergalactic voids.
But it's equally valid to consider it something which can be measured [wikipedia.org]
Measurement implies a spectrum - and as soon as you consider a spectrum of vacuum you realize there's only one natural lower bound for "minimum vacuum" - ambient pressure.
Noticed the first category they describe:
Mars is at the low end of that range, and a far stronger vacuum than would be used in, say, industrial vacuum-forming.
Also note slightly further down the page: relative measurement [wikipedia.org]
Which yes, implies negative vacuum at pressures above ambient where there is no vacuum
And yeah - you can use parachutes, etc. on Mars because there's still dense enough air there for it to be useful if they're big or fast enough.
But you can also build an electrostatic solar wind sail to propel yourself through the vacuum of interplanetary space using the continuous flow of ionized hydrogen from the sun. Dense enough air to be useful there as well.
(Score: 2, Informative) by Anonymous Coward on Thursday August 18 2022, @05:57PM
https://www.researchgate.net/publication/269078684_Recent_Advances_in_Scale-Up_Development_of_Molten_Regolith_Electrolysis_for_Oxygen_Production_in_Support_of_a_Lunar_Base [researchgate.net]
Somewhere else, recently, I saw a study that looked at making a sort of concrete, using the waste products left after the O2 is removed by the process described above. The concept was a solar furnace that makes both oxygen and a building material.