A Low-Gee House made from Pee

[CalMeacham]

The European Space Agency said Friday that urea, the main organic compound in urine, would make the mixture for a “lunar concrete” more malleable before it hardens into its sturdy final form.

…

The agency said researchers in a recent study it sponsored found that urea, the main organic compound in urine, would make the mixture for a “lunar concrete” more malleable before it hardens into its sturdy final form.

It noted that using only materials available on site for a moon base or other construction would reduce the need to launch supplies from Earth.

The main ingredient in “lunar concrete” would be a powdery soil found on the moon’s surface known as lunar regolith. ESA said urea, which can break hydrogen bonds and reduce the viscosity of fluid mixtures, would limit the amount of water necessary in the recipe.

“Thanks to future lunar inhabitants, the 1.5 liters (3.2 pints) of liquid waste a person generates each day could become a promising by-product for space exploration,” it said in a statement.

Human Urine Could Help Make Concrete On Moon: Space Agency

This reminds me of the trade in urine in Imperial Rome:

A tax on the disposal of urine was first imposed by Emperor Nero under the name of “vectigal urinae” in the 1st century AD. The tax was removed after a while, but it was re-enacted by Vespasian around 70 AD in order to fill the treasury.[2][3]

Vespasian imposed a Urine Tax (Latin: vectigal urinae) on the distribution of urine from public urinals in Rome’s Cloaca Maxima (great sewer) system. (The Roman lower classes urinated into pots which were emptied into cesspools.) The urine collected from public urinals was sold as an ingredient for several chemical processes. It was used in tanning, wool production, and also by launderers as a source of ammonia to clean and whiten woollen togas. The buyers of the urine paid the tax.

The Roman historian Suetonius reports that when Vespasian’s son Titus complained about the disgusting nature of the tax, his father held up a gold coin and asked whether he felt offended by its smell (sciscitans num odore offenderetur). When Titus said “No”, Vespasian replied, “Yet it comes from urine” (Atqui ex lotio est).[4][5]

Pecunia non olet

If there ever develops a lunar capitalist economy, I could see a vectigal unnae being enacted.

[Kropotkin]

I’m going to go all Howard Hughes now and start stockpiling my urine! Dopers with experience in urine storage and launching IPOs welcome. Also venture capitalists who want to get in on the ground floor. Would provide more details, but I’m going to create another pint of liquid assets

[Roderick_Femm]

If you use urine for construction, there will be that much less that can be distilled (or whatever process) back into potable water. So I assume that this proposal counts on the existence of water ice on the moon. Which would probably make it necessary for settlements to be near the poles where water ice is most likely to be found, and for there to be plenty of it.

[panache45]

This sounds like a really piss-poor idea.

[Acierocolotl]

The only reports I’ve found on the use of urea as a retardant in concrete required 7.5% urea by mass. So for every kilogram of concrete, you’d need 75 grams of urea. Urea concentration in typical wazz is 9.3 g/L, so roughly 8000 liters of pee for a single tonne of concrete… which is enough for a square plate 2.5 meters a side, 8 cm thick.

At 1.5 liters of tinkle a day per astronaut, it would take 15 astronauts a full year to generate enough urea for a tonne of concrete.

As an added “bonus”, the concrete curing reactions decomposes the urea into ammonia. The offgassing would make that room smell… distinct, to put it mildly.

[Kropotkin]

Well, that’s just great. What am I supposed to do with all the Mason jars I ordered from Amazon?

[Acierocolotl]

Well, Kropotkin, they ARE gonna need skating rinks on the moon.

[Sicks_Ate]

@panache45

This sounds like a really piss-poor idea.

Easy there, this thread is rated Pee-Gee.