Skip to comments.Research team recreates ancient underwater concrete technology
Posted on 04/09/2005 4:19:02 AM PDT by Mike Fieschko
Research team recreates ancient underwater concrete technologyCU-Boulder history Professor Robert Hohlfelder, an internationally known underwater archaeologist, said scholars have long been in awe of the engineering feats of the early Romans. A former co-director of the international Caesarea Ancient Harbor Excavation Project, he said the research effort was spurred by the stunning hydraulic concrete efforts undertaken at Caesarea Harbor in present-day Israel and elsewhere in the Mediterranean before the time of Christ.
A University of Colorado at Boulder professor and his colleagues have taken a page from the writings of an ancient Roman architect and built an underwater concrete pier in the manner of those set in the Mediterranean Sea 2,000 years ago.
Hohlfelder, who teamed up on the project with London architect and archaeologist Christopher Brandon and Greek and Roman Studies Professor John Peter Oleson of Canada's University of Victoria, said the writings of ancient Roman Pollio Vitruvius provided a key starting point. Vitruvius published 10 books on architecture circa 25 B.C. describing the building and engineering methods practiced during the Roman Empire, including ancient harbor construction.
"The writings of Vitruvius are a window on the engineering efforts of ancient Romans," said Hohlfelder. "But we still had a number of questions about the use of ancient hydraulic concrete, and felt the only way to answer them was to attempt our own project based on what the ancients did and the materials they used."
The three researchers formed the Roman Maritime Concrete Structure Study, or ROMACONS, in 2002, and began collecting and testing hydraulic concrete cores from early Roman structures around the Mediterranean region. In addition to analyzing the composition and strength of different cores, they also were able to trace raw materials to specific Mediterranean sources with the help of CU-Boulder geology Professor Charles Stern, illuminating ancient trading patterns.
While Vitruvius explained how to build the wooden forms for underwater concrete structures, he did not specify how they were anchored to the seafloor, how the mortar was poured, how aggregate materials like stone chunks were added or how long it took the concrete to cure, Hohlfelder said.
In 2004, the team obtained a study site through the Italcemente Group, an Italian concrete company with a marine testing station in the harbor of Brindisi, Italy, to build a free-standing concrete pier, or "pila" -- a common feature in ancient Roman harbors. They designed the pila to be small -- about two meters on a side and two meters high -- reaching just above the water's surface at high tide, he said.
In September 2004 the team drove wooden planks into the submerged seafloor to make the forms, which were reinforced with horizontal beams to form a box. "We had seen impressions of these vertical wooden planks in Roman concrete, and wondered if the cracks between planks had to be caulked to prevent concrete leakage," he said. "But the thick mix they used may have made this unnecessary."
They used the Roman recipe for concrete passed down by Vitruvius. It included seawater, lime and sand (pozzolana) and chunks of volcanic rock from the Bay of Naples -- the same source for material used in ancient construction efforts at Caesarea and elsewhere in the region. The lime powder combined with sand and water made up the mortar, which would bind the aggregate into a solid mass of concrete.
Individual loads of the mortar were plopped into the form by the team using a wicker basket rigged with a "trip-line" modeled after ancient Roman illustrations of construction scenes with similar baskets and from actual artifacts recovered by archaeologists from an ancient shipwreck site near Pisa, he said. The team used hand tools to tamp the aggregate into the mortar as the structure slowly rose from the seafloor.
The three men finished the pila in September 2004 after using 13 tons of raw material and expending 273 work-hours, capping the top with paving stones in the manner of the early Romans. "We believe this is the first structure built with these materials and techniques in at least 1,600 years," said Hohlfelder.
The team will extract cores from the pila and analyze them later this year to assess the underwater curing rate of the concrete, he said.
"We think we have a better idea now about what went on day-to-day when Caesarea Harbor and other ports in the Mediterranean were being constructed," he said.
Hohlfelder has studied ancient shipwreck remains off Cyprus, Greece and Israel and 10 ancient harbors -- including the submerged town of Aperlae in present-day Turkey -- during his academic career at CU-Boulder.
The 100-acre Caesarea Harbor, the world's first port constructed in the open sea, is considered one of the most innovative and successful engineering feats of the ancient world. Framed by two artificial breakwaters and containing a lighthouse, towers and warehouses that served ships throughout the Mediterranean for more than 1,200 years, the harbor was completed about 15 B.C.
Source: University of Colorado at Boulder
sub-aqua concreto pingo-rama
This reminds me of a radio program I heard a few years ago which suggested that the Pyramids in Egypt were fashioned out of synthetic sandstone. The person being interviewed [I forget what program it was--it was one I'd never heard of as I was driving hundreds of miles out of range of my usual radio stations] said that she'd determined a means of making synthetic sandstone using only materials and technologies which would have been present in ancient Egypt. Transportation of huge blocks would have posed much less of a technical challenge if they were ground, then transported, and then reformed.
Please FREEPMAIL me if you want on, off, or alter the "Gods, Graves, Glyphs" PING list --
Archaeology/Anthropology/Ancient Cultures/Artifacts/Antiquities, etc.
The GGG Digest -- Gods, Graves, Glyphs (alpha order)
Etruscan Engineering and Agricultural Achievements: The Ancient City of Spina
The Mysterious Etruscans
Last modified on Tue, 17-Aug-2004 15:36:27 GMT | editors
Posted on 08/17/2004 9:05:30 AM PDT by SunkenCiv
From Hand-drag to Jumbo: A Millennium of Dredging
IADC (International Association of Dredging Companies) | 1999 | IADC
Posted on 07/30/2004 8:27:24 AM PDT by SunkenCiv
Sounds like Margaret Morris, coauthor of Joseph Davidovits' book on geopolymerization processes possibly used by various folks, particularly the ancient Egyptians, to synthesize stones of widely varying sizes and uses.
y'know, maybe Davidovits' stuff would make a good FR/GGG topic...
I never knew concrete could be poured without Mexicans.
Thanks $1,000,000. That sounds exactly like what I was talking about, and it looks as though it's not some crackpot theory but is actually quite solid. I wonder why I'd not heard of that theory before the radio program?
The book came out, hmm, maybe 1983? Anyway, I picked it up from William Corliss' book catalog and found it quite interesting and compelling, unlike the "pyramids were water purifiers" or "pyramids generated electricity to run the ancient Dremel tools" claims. ;')
Thanks for the interesting ping. It never ceased to amaze me what the Romans could do with sand/gravel, burnt limestone/gypsum, water, and a lot of laborers.
Any links/leads on the more nuts & bolts (or is that nails & pegs?) of the actual form building? My job used to entail building them; it was up to the mudders to fill them, so you can see where my interest is.
I'm a little curious about that myself.
The art of underwater concrete casting was perfected by the Romans, but their concrete was quite different from the concretes used today. I've seen the process reproduced (on a video of course) and with the addition of water the mixture started to "boil". The Pantheon in Rome, which in its time (and for some time thereafter) was the largest dome in the world, and is still standing, was constructed (if memory serves) of concrete.
a translation online, by one Bill Thayer (I couldn't get it to load):
same work, different URL, now it's bedtime for 'Civ:
Oh, I like this guy already:
"Another orphan text that no one wanted to enter, but that many nevertheless will be glad to see online. (Why is it that the self-aggrandizements of Cicero, the lecheries and whining of Ovid and the blatherings of that debauched old goose Seneca made it onto the Net before the works that give us solid technical information about what Rome was really good at, viz. the construction of her great buildings and works of engineering?)" -- Bill Thayer
>>I've seen the process reproduced (on a video of course) and with the addition of water the mixture started to "boil".<<
Thanks for those links. Without looking further tonight---bad toothache---I'll guess the boiling was from using quick lime, calcium oxide:
1. n. [Drilling Fluids] ID: 1769
A chemical with formula CaO, commonly called quick lime or hot lime. When hydrated with one mole of water, it forms slaked lime, Ca(OH)2. Quick lime is used in preference to slaked lime at oil-mud mixing plants because it generates heat when it becomes slaked with water and therefore speeds up emulsification by the reaction to form calcium-fatty-acid soaps.
The adding of water would convert it to slaked lime, the prime ingredient of 'natural' (as opposed to modern 'Portland') cement.
[Quick lime was also used sparing to sprinkle down the hole of outhouses, to control oder, insects, etc. It is also the lime used to sprinkle on dead critters until [if ever] they can be picked up by the knacker or animal control. It will burn the skin, which is why pre-slaked lime is used for such things as white-wash & plaster; it is safer.]
Nah, everyone knows the pyramids were built by aliens in
order to generate power for the satellites that watch us.
Thank goodness for Reynolds Wrap. ;')
a few links and quotes:
The Pantheon-- Rome -126 AD
A temple to all gods - by Freda Parker
"Though the Romans had been building with concrete since about 200 BC, work on the Pantheon was difficult and proceeded in gradual stages... Vitruvius (cir. 20 BC), a noted Roman architect, recorded the process followed in his day, that was probably still used by the Pantheon's builders. The ancients hand mixed wet lime and volcanic ash in a mortar box, adding very little water so that they got a nearly dry composition. They carried this mixture to the job site in baskets and poured it over a prepared layer of rock pieces. They then tamped the mortar into the rock layer. The tamping packed the mortar, reduced the need for excess water, but, at the same time, stimulated bonding... Eventually, work began on the concrete dome, constructed in tapering courses or steps that are thickest at the base (20 feet) and thinnest at the oculus (7.5 feet). The Romans used the heaviest aggregate, mostly basalt, at the bottom and lighter materials, such as pumice, at the top. They embedded empty clay jugs into the dome's upper courses to further lighten the structure and facilitate the concrete's curing. In the dome's construction, the Romans probably used temporary wooden centering on which they layered concentric rings of masonry and concrete."
[derivative material at http://www.aviewoncities.com/rome/pantheon.htm ]
"The building is circular with a portico of three ranks of huge granite Corinthian columns (8 in the first rank and 16 in total) under a pediment opening into the rotunda, under a coffered, concrete dome, with a central opening (oculus), open to the sky. The height to the oculus and the diameter of the interior circle are the same (43 metres), so the whole interior would fit exactly within a cube. The dome is the largest surviving from antiquity, and was the largest dome in western Europe until Brunelleschi's dome of the Duomo of Florence was completed in 1436."
By David Moore, P.E., 1995
"Unrecognized, the design of this ancient concrete building reveals unparalleled features not encountered in modern design standards. Recent studies reveal several major cracks in the dome, but it still functions unimpaired. This condition will surely excite the curiosity of our structural engineers. The building was built entirely without steel reinforcing rods to resist tensile cracking, so necessary in concrete members, and for this concrete dome with a long span to last centuries is incredible. Today, no engineer would dare build this structure without steel rods! Modern codes of engineering practice would not permit such mischief. No investor with knowledge of concrete design would provide the funding."
Design, Meaning, and Progeny
by William L MacDonald
|GGG managers are SunkenCiv, StayAt HomeMother & Ernest_at_the_Beach|
Just updating the GGG info, not sending a general distribution. Posted April 9, 2005
A fun way to learn about Roman engineering use of concrete is the novel, Pompeii by Robert Harris.
The novel is about a young “aquarius” or aquaduct engineer who gets the first warning about Vesuvius when problems start to occur in the water supply in Pompeii and Misenum a couple of days before the eruption.
Mixed in with his solving of the mystery of why the aquaducts aren’t working or have sulphur in the water is great information about the engineering of aquaducts, the core of which was the cast concrete water main.
You may not think this provides a great read, but I’m probably not giving a good enough precis to make it come alive—but give it a shot. As days pass and he begins to climb through the aquaducts onto the slopes of Vesuvius you want to shout, “Forget the damn water main. Grab your girl and get the hell out before the volcano blows.”
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