There are many traditions, recipes, or construction methods that we have inherited from the Roman Empire. In this case, we will focus on construction, specifically on Roman concrete and the differences with the concrete manufactured today. This is a study carried out by engineer Daniela Martinez from the University of the North in Colombia. It analyzes both types of cement and seeks useful ways to improve the modern one. One of the most important aspects studied is the amount of CO2 emissions generated by the different types of production. In the case of Roman cement, it is considered to be more polluting although it produces less harmful emissions.
Moreover, it offers much greater durability, which makes it more sustainable in the long run. On the other hand, current cement, known as Portland cement, generates more greenhouse gas emissions and consumes a large amount of water. Unlike Portland cement, Roman cement was capable of self-regeneration, as it would naturally bond with water when cracks appeared. In contrast, current cement requires repairs with steel, which oxidizes and expands with heat, necessitating further repairs. According to Paulo Monteiro from the University of Berkeley, the corrosion of reinforcement is the main cause of concrete deterioration.
One of the characteristics they share is that both have the same main ingredient; quicklime. However, nowadays it is mixed with water, while the Roman version was mixed with volcanic rocks. Studies have shown that Roman manufacturing could reduce nitrogen oxide and sulfur oxide emissions by 98%. According to Narayanan Neithalath, a materials scientist at Arizona State University, if cement manufacturing were compared to a country, it would rank behind China and the United States, being the third largest emitter of carbon dioxide.
Heritages of the Roman Empire
The heritage we receive from ancient civilizations like the Roman Empire has an invaluable worth. In any field we look into, we will find improvements, comparisons, or similarities with this advanced civilization. This is the case with cement manufacturing. This aspect has been the focus of Daniela Martinez, author and engineer from the study at the University of the North , published in iScience, who wanted to analyze what improvements could be adopted regarding greenhouse gas emissions. One of the most revealing pieces of information was that the production of Roman cement requires more water and generates more greenhouse gas emissions at first, but it is much more sustainable than the cement used today, Portland cement.
Roman cement vs. Portland cement
Despite being considered more polluting in production, the truth is that it is more sustainable and durable than Portland cement. One of the characteristics of Roman cement is its ability to “self-regenerate”. Yes, you read that right. In case a crack forms, simply coming into contact with water allows it to bond naturally. This is why Martinez stated, “When we take into account the lifespan of concrete, that’s when we start to see benefits”.
For its part, Portland cement does not have this capability. Currently, concrete structures are reinforced with steel. The problem lies in the fact that this material oxidizes, causing the concrete to crack and degrade. According to Paulo Monteiro from the University of California, Berkeley, “The corrosion of the steel reinforcement is the main cause of concrete deterioration, so comparisons must be made very carefully”.
Different ingredients
It is noteworthy that both have the same main ingredient, quicklime, which is the result of heating limestone. However, Portland cement combines it with water and later with gypsum, while Roman cement not only burns limestone with oak and fir wood, but also mixed the resulting mortar with volcanic stones. Studies reveal that if Roman techniques were applied, nitrogen oxide and sulfur oxide emissions would be reduced by 98%. According to Narayanan Neithalath, a materials scientist at the University of Arizona, “If we have a reasonable chance of staying below the two degrees Celsius warming target set by the Paris Agreement, cement-related emissions will have to decrease by more than 20 percent in the next decade”.
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