Making cement from scratch is a massive pain

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Originally published at: https://boingboing.net/2018/07/20/making-cement-from-scratch-is.html

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I mean, it probably has lots of calcium hydroxide, but potentially a whole host of other alkali components, making it more akin to a geopolymer:


Seems labor and material intensive. He has streams nearby his site, as shown by his prawn trap video, why not gather shells and go with something like tabby cement?

Tough getting a lot of freshwater mussel shells, but volume wise and energy expendature wise, has to be a better effort. Plus, if he gets live ones, he has a protein source.
edit: Apparently he used forest snail shells to make a lime prior. Still seems like a less abundant source than mussels/clams: https://primitivetechnology.wordpress.com/2018/03/06/lime/

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The Primitive Technology videos usually have captions describing the steps. But you (may) need to turn them on.

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missing the key ancient ingredient - slaves

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If you want to super charge it you need sticky rice (if using mortar) and rice husk ash for cement.

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It was probably less of a pain when you had a whole industry making it and a larger work force.

IIRC the stuff the Romans made is still considered some of the best stuff ever made.

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Romans and Chinese. If i recall correctly the Chinese cement actually gets harder over time. It’s likely that the Roman made stuff does something similar.

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Yeah. I think he’s too far upstream for a decent amount of shells. Once you’re past the first fall line, crayfish and snails are around, but not in great quantities. He’ll likely need to make a lot of long trips to bring back a decent source of lime.

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I live not too far from Lime Kiln Road. All over the eastern US there are hundreds of Lime Kiln Roads. This is why.

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I don’t live an a Lime Kiln Road, but there are the remnants of a lime kiln about 3 miles down the road from me. Not too unusual around this area though…

http://www.s120804860.onlinehome.us/limekilns/limekiln.html

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That’s the Appian Way!

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I’m not aware of any concrete/cement that doesn’t increase in compressive strength over time. It really tapers off though so for engineering purposes the 28 day compressive strength is typically used as the “strength” of the concrete. Google “concrete strength curve” and check out the shape of the graph.

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The Romans used a particular volcanic ash that had a unique chemistry and morphology as linked by @FGD135 above

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Yup:
“The Romans used volcanic pumices and tuffs found in neighbouring territories, the most famous ones found in Pozzuoli (Naples), hence the name pozzolan, and in Segni (Latium).”
Good stuff, and the Roman engineers knew how to use it.

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Freshwater mussels are also apparently much less tasty than their saltwater brethren.

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I watch the Primitive technology channel as a stress relief and ambient noise for working (there I am just listening ASMR-like to jungle sounds). iirc he has a previous video where he collects gobs of terrestrial snail shells and make cement from those as well. He was right on the cusp of metallurgy at the old site.

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The European colonists had the advantage of having massive prehistoric shell middens to mine.

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The Classic Maya collapse may have been due in part to the deforestation caused by plaster production for construction-- 20 trees per square meter of city. http://www.pnas.org/content/pnas/early/2012/08/21/1210106109.full.pdf

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Not sure why either. They have jetties made of the stuff still in use after 2000 years. Trying to duplicate the chemistry behind it.

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