STRUCTURES THAT LAST 2,000 YEARS. HOW DID …

1 CONSTRUCTOR/September 200213 NBCN ightly News, August 7, 2002,Matt Lauer anchoring: It was one ofthose catchy, uplifting, end-of-thebroadcast stories. It seems a man has beenstealing coins for 30 years out of a publicfountain. Not just any fountain, mind you, butthe Trevi fountain, in Rome an icon ofromanticism immortalized in the Fellini film La Dolce Vita and the American classic, Roman Holiday, with Audrey Hepbu r n .Lovers and tourists are seen frolicking aboutan old-world fountain complex of spectacularbeauty, the water looking as clean and pureand effervescent as if poured from a millionbottles of is said, the reporter intones, that if youturn your back to the fountain, make a wishand flip a coin over your shoulder into thewater, your wish will come true and indeedthe video captures people doing so. Themoney, the reporter continues, is supposed togo to a Catholic charity, but now this man the video shows a suitably crazed-lookingRoman first taunting police, then being cartedaway has been arrested for stealing it!

2 It is never said how he got away with it for30 years. But no matter:n ow comes thedenouement, the silver lining: He can takeaway my money, a pretty young woman saysto the television camera, but he can nevertake away my wish. THE REALLYROMANTIC STORYHmmm. Not bad unless you know thereallyromantic story NBC missed. Fromwhence, might you suppose, does the waterfor the Trevi fountain come? The municipalwater supply?Nope. It comes directly fromthe Salone springs, some 11 miles outside ofRome, and it is delivered there by the AquaVirgo, a Roman concrete aqueduct built in theyear 19 during the reign of CaesarAugustus. Put another way, Jesus Christ wasnot yet born when this aqueduct was built and it is still delivering water to the knew this because I d seen the NOVAdoc-umentary on public television, RomanBath,which devoted considerable attention andvideo footage to the aqueduct that gracefuland beguiling monument to Roman ingenu-ity.

3 The Romans would not take no for ananswer, says Peter Aicher, author of Guideto the Aqueducts of Ancient Rome. Just likethey conquered other people, they would con-quer nature with their engineering. In the end,for this city of a million people, they had 11aqueducts, 11 channels of over 300 miles,delivering perhaps 150 to 200 gallons perperson per day, an amazing amount for theancient world. The most stunning footage of all wa sdevoted to the Romans Aqua Claudiaaque-duct. Prized for its sweet-tasting mountainspring water, it stretches 50 miles beyondRome, reaching into the foothills of theApennines. The water travels its first 40 milesu n d e rground. But eve n t u a l l y, mountainscome to an end, said the Roman Bathnarra-tor. that s when aqueducts emerge, in aspectacular display of Roman arcades of arches, 60 feet high, car-rying water in channels along the top. Spectacular indeed. Watching the show, Ibecame engulfed in a wave of splendid nos-talgia, recalling a certain sun-splashed fallmorning some 32 years prior, on which I firstencountered Roman construction.

4 It was inMrs. Olaette Cerny s Latin I class, and thesubject was Via Appia the Appian Way that most famous and important of Romanroads, portions of which are still in use in 312 by the Roman censorAppius Claudius Caecus, it was the mainroute from Rome to Greece, stretching some350 miles. Roughly 20 feet wide, it was largeenough to permit two chariots, one per lane,to travel simultaneously. It even had restareas every 10 miles or so horse changingstations with taverns and, of course, back to Roman Bath: This bridge car-ried two aqueducts, the narrator continues, the Aqua Claudiaon the bottom and themostly missing channel of the Anio Novisaqueduct on the top. My head spun. Anunderground water main, 40 miles long?Anabove-ground, 60-foot high, double-deckeraqueduct?Equally impressive:the aqueductsran solely on gravity so the entire 50-milelength of the Aqua Claudiawas built on aprogressively downward slope.

5 How was thispossible, given the limitations of ancienttools and technology?The engineering and construction wa simpressive, no question. But like a lightbulbgoing off in my brain, I recalled at that veryinstant preciselywhat it was that had so cap-tivated me as a schoolboy so many yearsTHESECRETSOFROMANCONCRETEIMAGINEBUI LDINGSTRUCTURESTHATLAST2,000 Colosseum, or Flavian Amphitheater, sitsnear the southeast end of the Forum, betweenthe Palatine and Esquiline hills of by the Emperor Vespasian in circa , and completed by his son Titus in , it is the most imposing of Roman antiq-uities. The vast, four-storied oval is 617 feetby 512 feet, much of which is still to the ages are tier on tier of marble seatsthat originally accommodated some 45,000spectators, but were looted by succeedinggenerations. The Colosseum encloses anarena measuring 250 feet by 151 feet, thesite of gladiatorial combats until 404 structure has been damaged severaltimes by earthquakes and fire, but those por-tions built with Roman concrete endure.

6 Stephani MillerROMAN CONTRACTORS & CONTRACTS Aside from the employment of soldiersfrom the Legion, and government slaves,which were common in the ancient states,the main construction force behind thebuilding of large projects, excluding themany military roads, bridges and fortifica-tions, were fact they pos-sessed the same basic function of ourmodern contractors, writes David Moore. They even had the same gripes. Hequotes the Roman engineer Vitruvius, asfollows: things of this sort should beknown to architects, so that , before theybegin upon buildings, they may be carefulnot to leave disputed points for the house-holders to settle after the works are fin-ished, and so that in drawing up contractsthe interests of both employer and con-tractor may be wisely safe-guarded. As to construction contracts, saysMoore, the Romans employed highlysophisticated oral and written contractsthat were explicit in assigning detailedresponsibilities for all parts of the job,including labor and materials and therewere even arbitration clauses.

7 (continued)Photo by Lakisha Campbell14 CONSTRUCTOR/September 2002before:concrete. How in the heck did theRomans make it to last 2,000 years? Whatwas different about their methods and whatcan we learn from them?Long ago, I real-ized, I had tied a string around my finger. Itwas still there. USED BY PATTON S ARMIES The aqueducts, I knew, were just one ex a m-ple of Roman concrete. In World War II, Gen. George S. Patton, a celebratedmystic who believed himself to be a reincar-nated ancient wa r r i o r, took great satisfaction indirecting the Seventh and later the Third armyover bridges used by Julius Caesar, Sulla,P o m p ey, and other Roman commanders. From the Colosseum, to the Pantheon, tothe Arch of Constantine, to numerous sites inRome, to the ruins of Pompeii and Romanestates, throughout much of the Mediter-ranean basin, northward to Britain andthroughout much of Europe, there are liter-ally thousands of Roman concrete works stillwith us today.

8 Many of them are crumbling,but quite a few, like the Pons Fabricius bridgein Rome, connecting the left bank of theTiber river to Tiber Island, are structurallysound and still in ewly inspired, I hopped on my computer,logged onto , and typed thewords Roman Concrete into the searchengine. Somebody, surely, the scientists t h ey must have figured it all out long ago. Butnothing came up. Next I logged , typed the same words into theb r ow s e r, and bingo: 88,000 references. Mostof what I found, how eve r, was either ske t c hy,boilerplate, repetitive, or anecdotal. Certainlythere were some tantalizing snippets, unive r-sity postings in particular, but nothing com-p r e h e n s ive, not one discrete publicationwholly devoted to Roman concrete. I didunearth one shiny nugget, how eve r :a nintriguing website, w w w. r o m a n c o n c r e t e . c o m,which in turn touted a book, The Roman Pa n-theon The Triumph of Concre t e, written byD avid Moore, THE DEFINITIVE STUDYSoon I was on the horn talking with Moore,a most courtly and agreeable gentleman, whovolunteered to send a copy.

9 When it arrived, Ifound to my great satisfaction that the titlewas misleading. Although it begins with anexploration of the Pantheon in voluptuousdetail, the overwhelming bulk of this 239-page masterpiece, richly detailed and exquis-itely footnoted, comprises the defi n i t ivestudy of Roman concrete who, where,when, what, why, and how. Moore drawsheavily on ancient Roman sources, quotingextensively the five authors whose writingson concrete remain Cato the Censor, Mar-cus Vitruvius Pollio, Pliny the Elder, Statiusthe Poet, and the Emperor Julian. He also presents a rigorous boil-down ofcontemporary scientific and historical inves-tigation, quoting such well-known sources asNational Geographicand classical scholarsfrom Yale University and Oxford (England)University, as well as such obscure but vitaldocuments as The Water Cisterns of OreWa s h e rs in Laurion and Their SpecialHydraulic covers every conceivable base, fromRoman construction machinery, tools, train-ing, and construction practices to an essentialreview of Roman society and contracting, toa scientific and historical perspective onRoman lime and kilns, clay products andmortar, pozzolan-lime behavior and muchmore.

10 It was all here. This, indeed, was theanimal I had sought, and, further, it was ren-dered in clear, lucid prose and a surprisinglyjaunty style. I knew I was in trouble when Ifound myself reading it on a Saturday : A BRIEF PRIMERSo what arethe secrets of Roman con-crete? One cannot condense a fat book withinnumerable scientific details into a three-page article, but there are some general prin-ciples that can be shared. Let us begin with abrief primer on concrete. Concrete is a com-bination of aggregates, typically sand andgravel (although the Romans, notably, usedl a rger stones see sidebar above, right)mixed within a cementitious paste that hard-ens to create a single mass that can resistgreat compressive forces. Basic lime-basedmortar, such as that originally used by theRomans, is made possible by the uniquechemical properties of calcium carbonate,which is found in abundance throughout theworld in the form of limestonewhich cont a i n sthe elements calcium, carbon, and oxygen.