Introduction
History contains many references to ancient concrete, which turns out to have been exceptionally strong and durable.
One of the first came in the writings of the famous Roman scholar Pliny the Elder, who lived in the 1st century A.D. and died in the eruption of Mt. Vesuvius in A.D. 79. Pliny wrote that the best maritime concrete was made from volcanic ash found in regions around the Gulf of Naples, especially from near the modern-day town of Pozzuoli. Its virtues became so well-known that ash with similar mineral characteristics—no matter where it was found in the world—has been dubbed pozzolan.
By analyzing the mineral components of the cement taken from the Pozzuoli Bay breakwater at the laboratory of University of California at Berkeley, as well as facilities in Saudi Arabia and Germany, the international team of researchers was able to discover the “secret” to Roman cement’s durability. They found that the Romans made concrete by mixing lime and volcanic rock to form mortar. To build underwater structures, this mortar and volcanic tuff were packed into wooden forms. The seawater then triggered a chemical reaction, through which water molecules hydrated the lime and reacted with the ash to cement everything together. The resulting calcium-aluminum-silicate-hydrate (C-A-S-H) bond is exceptionally strong.
By comparison, Portland cement (the most common modern concrete blend) lacks the lime-volcanic ash combination and doesn’t bind well compared with Roman concrete. Portland cement, in use for almost two centuries, tends to wear particularly quickly in seawater, with a service life of fewer than 50 years. In addition, the production of Portland cement produces a sizable amount of carbon dioxide, one of the most damaging of the so-called greenhouse gases. According to Paulo Monteiro, a professor of civil and environmental engineering at the University of California, Berkeley, and the lead researcher of the team analyzing the Roman concrete, manufacturing the 19 billion tons of Portland cement we use every year “accounts for 7 percent of the carbon dioxide that industry puts into the air.”
In addition to being more durable than Portland cement, argue, Roman concrete also appears to be more sustainable to produce. To manufacture Portland cement, carbon is emitted by the burning fuel used to heat a mix of limestone and clays to 1,450 degrees Celsius (2,642 degrees Fahrenheit) as well as by the heated limestone (calcium carbonate) itself. To make their concrete, Romans used much less lime and made it from limestone baked at 900 degrees Celsius (1,652 degrees Fahrenheit) or lower, a process that used up much less fuel.
The researchers’ analysis of Roman concrete sheds light on existing modern concrete blends that have been used as more environmentally friendly partial substitutes for Portland cement, such as volcanic ash or fly ash from coal-burning power plants. Monteiro and his colleagues also suggest that adopting materials and production techniques used by the ancient Romans could produce longer-lasting concrete that generates less carbon dioxide. Monteiro estimates that pozzolan, which can be found in many parts of the world, could potentially replace “40 percent of the world’s demand for Portland cement.”
If this is the case, ancient Roman builders may be responsible for making a truly revolutionary impact on modern architecture—one massive concrete structure at a time.
Roman Concrete
Stretching from England to parts of Africa and the Middle East, the Roman Empire rose to power around two thousand years ago and flourished as one of the strongest empires to ever exist. It is argued by many people that a specific technology utilized by the Roman Empire was the driving force of Rome and the fall of the great empire followed the decline of this innovation. What innovation from two thousand years ago could both birth and kill an empire? The Romans called it “opus caementicium”, but today we simply call it Roman concrete. The concrete was made from three components: aggregate, mortar, and facing. The aggregate was made from stones, terra cotta, or tiling. The mortar was created by mixing lime, water, and ash or sand. The main ash that was used reacted with water and lime to create a strong and waterproof bond. Roman concrete also contained elements that reacted with water when damaged to self-heal and create stronger bonds. Their use of such a remarkable material, opus caementicium, drove the empire to its strengths by allowing construction and longevity of harbors, aqueducts, roads, sewers, and amazing structures.
Ancient Roman concrete famously known for its longevity and durability serves as a reminder how science, technology, and society intersect. The concrete composing of aggregate, mortar, facing, and other elements allowed the concrete to repair itself and grow stronger over time, something modern concrete is not able to do. This shows advanced knowledge of chemistry and materials science. Roman concrete also enabled the construction of famous structures such as the Pantheon and the Colosseum, aqueducts, and harbors demonstrating engineering and architectural practices showing their technological advancements. The use of this material also impacted society as it improved infrastructure, increased trade, and improved daily life across the empire. Not only has the use of concrete allowed for Rome to prosper and influence many aspects of life to this day, but Roman concrete also inspires modern scientists and engineers to create better, more sustainable, building materials.
Harbors
Before Rome’s concrete, harbors were built were only built in locations with advantageous geography or topography. The Romans revolutionized this practice by developing concrete that was able to set and harden underwater. This allowed for Rome to build more harbors in any location they deemed desirable. This allowed for a connection of ports and harbors between parts of Northern Africa to parts of Europe as well as the Middle East. With the now grand use and widespread construction of new harbors there was a connection between the world and the rise of the first global empire and economy.
Aqueducts
Aqueducts built with waterproof concrete were constructed throughout Europe allowing for transport of water over long distances. Being able to transport water over long distances now provided a steady supply of water to major cities throughout Rome. Aqueducts are seen today in countries including France, Spain, Greece, parts of Northern Africa, and to the east in Turkey.
This steady supply of water provided drinking water for the people of Rome. Aqueducts also transported water into cities to be used in irrigation. Water was also transported to public baths allowing for thousands of people to bathe, which helped increase sanitation and hygiene. Famous fountains attracting tourists from all over the world were supplied with water from aqueducts, in fact the aqueduct “Aqua Virgo” built in 19 B.C. still supplies the Trevi Fountain with water. It is unlikely that Rome would have grown to its power without the supply of water from aqueducts.
Roads, Sanitations and Sewers
The Romans didn’t just rely on new harbors to expand their economy and trading routes. Roads were also built throughout the empire connecting new cities and towns. Merchants were now able to expand their markets to never seen areas before. Many of the Romans roads were build using layers of concrete creating durable roads still seen and in use to this day.
Water was also provided to the city through aqueducts to improve sanitation. With the estimated 11 aqueducts built in Ancient Rome, water was now provided to fill public bathes allowing people to bathe and keep clean. Public toilets were now able to be flushed transporting feces out of the city. Sewers were also one of Rome’s earliest notable constructions. They were used to help transport waste from public baths reducing disease and ultimately improving sanitation. Sewers also helped drain areas experiencing floods from local rivers. The use of concrete to construct roads and sewers improved the daily lives of Romans while also creating a safer, more hygienic lifestyle.
Structures
Concrete took over as the main building material as it ended up being the most durable building material of the time allowing for construction of many different structures.
The famous Colosseum that still stands today acted as a public gathering place holding tens of thousands of people. This structure notably served as an arena for entertainment. The Colosseum most notably hosted the gladiator fights. Other events hosted at the Colosseum included chariot races, drama, staged animal hunts, staged naval battles, as well as hosting Greek athletes for Greek athletic contests.
Concrete also played an important role in Ancient Rome’s society by allowing religious structures to be built. With concrete as the new building material, the Romans developed new architectural forms such as barrel vaults and domes. The Pantheon is just one example of a structure still surviving in good condition to this day that utilized concrete. The Pantheon, famous for its dome, utilized the lightweight nature of concrete to create hundreds of molds. These molds were then connected to each other forming the dome.
Both of these structures are just some of the very few examples of structures built using concrete. These structures influenced society by shaping cultural values. The Colosseum was a place of gathering that allowed for maintenance of social order by providing entertainment and distraction to politics. The Pantheon provided a place for worship shaping society at that time.
Conclusion
Concrete was crucial to Rome’s development as it provided entertainment, religious places for worship, roads and ports which increased trade, and provided cities with water. The durable and self-healing concrete drove Rome to its success and has major influences in today’s society. Modern day science is also still influenced as researchers try to create more sustainable and durable construction materials built off Rome’s concrete. Without concrete Rome may have never reached its strength and vastness it is known for making concrete possibly one of the most important inventions of the time and to this day.
