Scientists give a reason why Roman concrete lasts so well: http://www.sciencedaily.com/releases/2014/12/141215185026.htm Do you have any concrete monuments to show us? I think most aqueducts and temples were simply stone, but the rounded roof of the temple for Divus Romulus, son of Maxentius (d. AD 309), might be concrete: Romulus. 24 mm. 5.56 grams RIC VI Rome 256 AETERNAE MEMORIAE Eagle rising from the top of the temple, symbolizing the spirit of Romulus ascending. According to Tameanko's book on "Monumental Coins" there were two temples to Divus Romulus, one on the Appian Way not far outside Rome by the Circus of Maxentius and this one, in Rome in the Forum, which was converted to a church. The extant remains (with only two columns and a cupola) differ in details from this type. I did not find confirmation that the dome was Roman concrete, but it reminds me of the Pantheon which is. Here is the second design: Romulus. 24 mm. 6.45 grams. RIC VI Ostia 34 The depiction of this temple is much different. It is without columns and with clear tiers of stones. Perhaps the rounded roof is an artistic way of showing a round temple (both were round), but again it seems like the famous construction of the Pantheon with concrete. Here is an aerial view of the Pantheon in Rome. Temples are common and Roman coins. I wonder how many monuments made with concrete we can present on coins.
To improve today’s concrete, do as the Romans did 2013.06.04 from http://newscenter.berkeley.edu/2013/06/04/roman-concrete/ "In a quest to make concrete more durable and sustainable, an international team of geologists and engineers has found inspiration in the ancient Romans, whose massive concrete structures have withstood the elements for more than 2,000 years." "Using the Advanced Light Source at Lawrence Berkeley National Laboratory (Berkeley Lab), a research team from the University of California, Berkeley, examined the fine-scale structure of Roman concrete. It described for the first time how the extraordinarily stable compound – calcium-aluminum-silicate-hydrate (C-A-S-H) – binds the material used to build some of the most enduring structures in Western civilization." CASH! How appropriate for this forum! The article above focuses in part on underwater concrete and reasons for it's durability. I have heard several times from Architecture professors that research has suggested that the composition of concrete in the dome of the Pantheon is different than in other structures, and that includes things other than just a concrete mix, things which take up space like fist sized pumice rocks which are very light and lessen the load pushing down from the massive domed roof. Pumice being exploded volcanic rock plays into the mix as the article suggests the Roman engineers used volcanic ash in the composition for maritime and other mortar applications. The Pantheon is a stunning building, absolutely nothing like it anywhere, IMO, which should be on any traveler's bucket list. Can't wait to see what coin pics you guys post!
Roman concrete is very impressive. While the Colosseum isn't quite as intact as it once was, it certainly has held together well, considering its age: The Port of Ostia a bit less so, although that's largely due to the reuse of its marble and falling into disuse more rapidly:
Neat article. Regarding the Temple of Romulus at the Forum, one other remarkable fact about it is that the green bronze doors you see on it today are the original ones from the 4th century. I wish I had the pictures I took of them, but they were lost in an iPhone mishap. http://penelope.uchicago.edu/~grout/encyclopaedia_romana/romanforum/romulus.html
