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Geopolymer concrete like the Romans

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Wrong and wrong again... The Romans cement was NOT more advanced (Score: 2, Insightful)

by tanuki64@pipedot.org on 2014-12-04 11:36 (#2VJT)

For all the things Romans got wrong (lead pipes anyone?) did you know we're still using a less advanced concrete than they did? Consider some of the massive structures in Rome that have passed the test of time, lasting for more than 2000 years. The typical concrete that we use in construction starts to degrade after only 50 years.
People, who make and repeat this claim, fall for some kind of selection bias. Actually there was no 'the Roman cement'. Mixing cement was no hard science back then. I doubt that even two batches were identical. So yes... some structures last more than 2000 years. But how many structures are gone because they did not even last 50 years? Erm... no one knows... because they are not there anymore. What we are seeing now are structures where the mixture was more or less coincidentally right and environmental factors were favourable so the structures survived.

Re: Wrong and wrong again... The Romans cement was NOT more advanced (Score: 2, Funny)

by insulatedkiwi@pipedot.org on 2014-12-04 17:29 (#2VK3)

Are you speaking from experience.. you were a Roman architect/builder?

Re: Wrong and wrong again... The Romans cement was NOT more advanced (Score: 3, Interesting)

by tanuki64@pipedot.org on 2014-12-04 20:37 (#2VKE)

Do I really need to be a Roman architect/builder?
Read this:
http://www.motherjones.com/kevin-drum/2010/09/counterintuitive-world

False conclusions are very common in many areas. I think it is the same with Roman cement.
You see what remained after 2000 years. But of course you don't see anymore what crumbled
after 50 years.

Re: Wrong and wrong again... The Romans cement was NOT more advanced (Score: 1)

by insulatedkiwi@pipedot.org on 2014-12-05 13:20 (#2VMA)

While I don't disagree that your premise may be correct, what makes you think that a society noted for its obsession with bureaucracy and incredible ability to organize (look where they built, and how they managed to keep garrisons weeks from Rome supplied) would not have had some recipe for cement, but that the amount of work or scarcity of materials prevented it from being used always?

Re: Wrong and wrong again... The Romans cement was NOT more advanced (Score: 1)

by tanuki64@pipedot.org on 2014-12-05 15:02 (#2VMC)

The Roman 'science' certainly was very advanced. Far superior than what came in the middle ages. However, I really doubt the Romans had the slightest idea what they were doing. Real material science came centuries later. So what they did came from trial and error.

I posted a link to a history of concrete:http://matse1.matse.illinois.edu/concrete/hist.html
Used pozzolana cement from Pozzuoli, Italy near Mt. Vesuvius to build the Appian Way, Roman baths, the Coliseum and Pantheon in Rome, and the Pont du Gard aqueduct in south France. They used lime as a cementitious material. Pliny reported a mortar mixture of 1 part lime to 4 parts sand. Vitruvius reported a 2 parts pozzolana to 1 part lime. Animal fat, milk, and blood were used as admixtures (substances added to cement to increase the properties.) These structures still exist today!
Fat? Milk? Blood? Oh, I am sure those materials really play an important role in the cement's durability. But I am also quite sure, that initially they were added for some sacrificial reasons. Not because the Romans knew that this really improved the cement. Furthermore the used material are natural materials. The composition of almost all natural materials vary a bit. Then: 1 part of lime and 4 parts of sand. Or 2 parts of pozzolana and 1 part lime... to what precision? Does it make a difference if it is 1.95 parts of pozzolana and 1.05 parts of lime? Does it make a difference where the lime came from? With all respect for the Roman accomplishments, but it is very unlikely that their cement had over centuries always the same quality.

IMHO this means either the allowed production tolerance is quite high, so that natural variations don't matter much for the cement's quality. Then it is surprising that the exact formula got lost. Or the allowed production tolerance is quite low, but this would support the theory that the Romans, too, did not always get it right and we only see the results where more or less by coincidence the mixture was perfect.

Re: Wrong and wrong again... The Romans cement was NOT more advanced (Score: 1, Insightful)

by Anonymous Coward on 2014-12-06 10:52 (#2VNG)

don't knock trial and error... how do you think we got here!

Re: Wrong and wrong again... The Romans cement was NOT more advanced (Score: 2, Interesting)

by tanuki64@pipedot.org on 2014-12-06 12:38 (#2VNK)

If I gave the impression that I want to belittle the Roman accomplishments... nope definitely not my intention. And of course, nothing wrong with trial an error. But on the other hand one should not make the mistake to ascribe the Roman some 'magical' understanding of what they were doing. Do you really think the Romans had laboratories where they experimented with different mixtures? Had huge fields with pieces of walls all with different cement to see which wall piece looked best after 500 years? All meticulously documented in lab-journals? I think not. So yes, trial and error....and plenty of luck. This does not make what they did with their cement less impressive.

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2014-12-09 03:34 Interesting +1 hairyfeet@pipedot.org

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