Must_dash
Contributor
Yep, concrete is good in compression, not in tension.....
I'm still amazed that the replacement was designed and built so quickly. We drove over it a few weeks ago.
Diving Roman ruins in Italy
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I'm still amazed that the replacement was designed and built so quickly. We drove over it a few weeks ago.
The recipe was not lost. During my second year of Engineering, my teacher of Applied Chemics did teach us the recipe of various types of concrete, including the pozzolanic one.
It went out of fashion for two reasons:
1) difficulty and cost of buying the pozzolana rock, a vulcanic rock only available on some small island North of Sicily, where extraction is now forbidden.
2) The pH too low, which causes corrosion of the steel bars employed in reinforced concrete.
OP
One of the things I do like about Scubaboard is when discussions go off topic. Some interesting facts have been shared. Thanks to.all participating.
Pozzalana
Widespread use of concrete had to wait until the early 1800s when the high heat and mechanized grinding made possible by newly introduced industrial processes allowed for cement production using inexpensive and relatively available limestone and clays.
Pozzolan is not restricted to Sicily. In Europe, it's found in multiple areas of Italy, Greece, and Germany. The name and most common source during Roman times actually comes from an area that's near Naples: it's called Pozzuoli today, but was Puteoli then and the sand used in cement was known as pulvis puteolanus, "dust of Puteoli". Maybe your professor was thinking of the Liparian pumice that they used as a component of concrete in many structures, including the roof of the Pantheon.
Pozzolanic concrete use largely disappeared from the end of the Roman empire in the 400s until the first known re-use in the 1300s. The republication of Vitruvius work on architecture in the 1400s led to the recipe becoming known throughout educated Europe by the early Renaissance, but economic conditions meant there was little use of it. Even in Roman times, while cement was commonly used as mortar, solid concrete was primarily used in grand works that had imperial backing.
Widespread use of concrete had to wait until the early 1800s when the high heat and mechanized grinding made possible by newly introduced industrial processes allowed for cement production using inexpensive and relatively available limestone and clays.
Pozzolan is not restricted to Sicily. In Europe, it's found in multiple areas of Italy, Greece, and Germany. The name and most common source during Roman times actually comes from an area that's near Naples: it's called Pozzuoli today, but was Puteoli then and the sand used in cement was known as pulvis puteolanus, "dust of Puteoli". Maybe your professor was thinking of the Liparian pumice that they used as a component of concrete in many structures, including the roof of the Pantheon.
The part about the pumice was the only thing I had definite in my memory. The rest required research.
As an aside, the dome of the Pantheon is the most impressive man made object I've ever seen. It would be fantastic if it were built today, but the fact that it has survived nearly 2,000 years is barely fathomable.
As an aside, the dome of the Pantheon is the most impressive man made object I've ever seen. It would be fantastic if it were built today, but the fact that it has survived nearly 2,000 years is barely fathomable.
Back to Baia, grazie for posting the underwater ruins photos. We lived in Baia in 1977 when I was 14 and we spent many an hour (and afternoon) exploring Baia baths, mostly all above water on the adjacent hillside, but with some parts submerged underwater.
The coolest was the so-called Oracle of the Dead tunnel, which terminates at stairs deep in a tunnel in the hill that descends down into what I remember as clear water. I've thought about diving that since I saw it last in 1977. If you do an online search for Oracle of the Dead and Baia, you'll find it. As dependent kids living overseas, we had our own Indiana Jones type thing going on after school and on weekends. I do hope to go back some time to visit and dive the underwater portion.
The coolest was the so-called Oracle of the Dead tunnel, which terminates at stairs deep in a tunnel in the hill that descends down into what I remember as clear water. I've thought about diving that since I saw it last in 1977. If you do an online search for Oracle of the Dead and Baia, you'll find it. As dependent kids living overseas, we had our own Indiana Jones type thing going on after school and on weekends. I do hope to go back some time to visit and dive the underwater portion.
OP
That's because of the yellow fever outbreak in Greece at the time. I believe they built a number of temples along the southern coast of Sicily.
OP
If I remember right there is a Parthenon in perfect condition in Sicily. It is hard for me to imagine with all the ruins I've seen in Greece
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