L'Italo-Americano

www.italoamericano.org 10 THURSDAY, JANUARY 13, 2022 L'Italo-Americano T he Romans cer- t a i n l y k n e w a t h i n g o r t w o about beautiful yet sturdy, long- l a s t i n g a r c h i t e c t u r e : I remember thinking just that the first time I visited the majestic Pont du Gard, in the South of France – closer to where I am from than Rome itself – a colossal aqueduct built in the 1st century AD to carry water to Nemausus, the city today known as Nîmes. Two thousand years old and still standing, just like the Coliseum, the Pantheon, or the Arena di Verona. And there is no magic involved, just concrete. Roman concrete has been studied by modern engineers for decades and it is easy to understand why: it lasts. It lasts more than any of our modern buildings will ever do, but why? To be fair, the Romans didn't invent con- crete, even though they are certainly the ones who made it famous. According to his- torians, the first concrete structures date back to 6500 BC and were built in Syria a n d J o r d a n : N a b a t e a traders would make houses, floors, and underground water cisterns with it. Later, around 3000 BC, concrete made its appearance in Egypt and China: Egyptians used gypsum mortars and lime in the construction of the pyra- mids, and a type of cement was also used to build the Great Wall of China, very much in the same period. But in these instances, the use of concrete was an excep- tion. What made things dif- f e r e n t i n R o m e w a s t h a t , t h e r e , b u i l d i n g w i t h i t became the norm. Concrete, with its initial malleability a n d i t s e t e r n a l s o l i d i t y , became the perfect instru- ment for Roman architects to exercise their ingenuity and creativity: with it, the sky was the only limit. But Roman concrete – the one that, with marble and travertine, made the caput mundi eternal – was not the same as the one we use these d a y s a n d i t ' s a l l d o w n t o c h e m i s t r y . A c c o r d i n g t o m o d e r n r e s e a r c h e r s , i t s chemical composition gives it a r e s i s t a n c e t h a t m o d e r n c o n c r e t e c a n n o t a c h i e v e . Today's concrete is made largely of portland cement - a combination of baked and crushed limestone, clay, silica sand, chalk, and other minerals - and aggregate, made up of sand and rocks. The aggregate strengthens the concrete and helps save on cement; when, in a final, w e l l - k n o w n s t e p , w e a d d water to the mix, chemistry binds together all the ele- ments. Concrete's composi- tion is such that once this ini- tial chemical reaction is com- pleted, no other takes place: in other words, modern engi- neers want their concrete to be as chemically inert as pos- sible, to avoid changes in c o m p o s i t i o n t h a t c o u l d p o t e n t i a l l y w e a k e n buildings. The Romans had a differ- ent view of things. Their con- crete was a much simpler affair, a mix of limestone and volcanic rock aggregates, eas- ily available around the capi- tal, and this is what made the d i f f e r e n c e . C o n t r a r i l y t o modern aggregate, volcanic rock is very reactive, which means Roman concrete could r e m a i n c h e m i c a l l y a c t i v e even after it hardened. But this was exactly what Roman engineers wanted because continuous chemical activity meant the concrete became harder and stronger in time. Marie Jackson, a geolo- gist at the University of Utah, w h o s e s t u d i e s f o c u s o n Roman concrete, explained it clearly to BBC Travel's Alex Fox: "Romans wanted their concrete to react. They chose an aggregate that would con- tinue to participate in the c o n c r e t e p r o c e s s e s o v e r time," and through which small cracks and damages, in fact, fixed themselves natu- rally. It is exactly this ongoing, long-lasting regeneration made possible by volcanic aggregate, that transformed Roman buildings into the symbol itself of longevity. To s a y i t w i t h R e n a t o Perrucchio, a mechanical engineer at the University of Rochester, NY, also cited by Fox in his article, "Modern concrete construction might last 100 years with mainte- n a n c e , b u t s o m e R o m a n s t r u c t u r e s h a v e s u r v i v e d 1000 years or more, essen- t i a l l y u n a s s i s t e d . " W e ' r e looking at you, Pont du Gard, Coliseum and co. The idea of using again R o m a n - s t y l e c o n c r e t e i s appealing, especially in light of today's efforts to create s u s t a i n a b l e b u i l d i n g s . A d m i r M a s i c , a n M I T material scientist, says that modern concrete may be sta- ble, but its production is far from being environmentally friendly because the produc- tion of Portland cement caus- es around 8% of the world's carbon emissions. Masic and Marie Jackson have been both working on applying their studies on Roman con- crete to today's needs, with the aim of making a more sustainable material. For instance, Roman con- crete only needs to be heated at 900C, basically half of the temperature needed for port- land cement: this alone could r e d u c e c a r b o n e m i s s i o n s associated with its produc- tion greatly. There are some drawbacks, though, because Roman concrete takes much longer to set than the mod- e r n : u p t o s i x m o n t h s , against the 28 days of port- l a n d c e m e n t . Y e t , M a s i c believes today's technology a n d s o m e r e s e a r c h c o u l d solve the problem, and he has been working on a poten- tial solution himself: inject- ing Roman concrete with car- bon dioxide could reduce curing time to only a handful of days. As he rightly points out in Fox's article, it isn't a m a t t e r o f c o p y i n g t h e Romans, but learning from them. L a s t b u t n o t l e a s t , w e shouldn't forget that, thanks to its durability, Roman con- crete could make structures stronger and reduce the need to replace them, another nod to sustainable architecture. In the end, to conclude with Masic's own words: "Making things last longer is perhaps the simplest way to improve sustainability." FRANCESCA BEZZONE Roman buildings resisted the test of time across the lands that once were part of the Empire (Photo: Sarit Richerson/Dreamstime) On how ancient Rome's buildings are still standing and their ingenuity could help us create more sustainable architecture LA VITA ITALIANA TRADITIONS HISTORY CULTURE

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