It does not fail. It seems mathematical. From time to time, the world rediscovers the Roman concrete and hallucin with the durability of a material that allows the Pantheon of Agrippa to have 2,000 years standing (while modern concrete cracks within a few decades). Incidentally, almost with the same regularity, there is some scientist or engineer who claims to have found the key secret that this is. The last occasion He has touched the Massachusetts Technological Institute And, as usual, the story is not exactly what it seems.
What does the study say? MIT researchers They have studied Small pieces of lime that are usually found in Roman concrete: the ‘calcium oxide’ clasts. These types of structures have been studied a lot in romas infrastructure located in maritime contexts and, for years, has been related to some “self -regime” capacity of the material.
Understanding what it means. According to some scientiststhe water that would enter through the concrete cracks would drag the calcium ions of the Classos in a process that would end up calcitating and sealing the cracks. The work of the MIT of recent days, also studies those clasts in the terrestrial concrete and theorizes that they are the result of the Romans added living lime to the mixture of the concrete (instead of the dull lime – calcium hydroxide – key of the Puzolenic reactions).
Beyond that, researchers They made several mixtures With living lime and verified that, according to their theory, in these new mixtures lime clasts were generated (and was calcited that repaired the cracks). As Brian Potter saysthe discovery is interesting at the historical level. But, despite the attempts to sell it as something revolutionary, it is potentially useless.
Useless? Yes, useless. When talking about Roman concrete, a lot of mistakes are usually made, but there are two recurring: the first, As Manuel F. Herrador always reminds usStructural concrete professor at the University School of the University of Coruña, is “the survivor’s bias.” The idea of the extraordinary quality of Roman concrete comes from studying, precisely, the best structures they did, which have best been preserved. On the other hand, most of what the Romans built has already disappeared completely and cannot be studied.
The second error. We are comparing ‘churras with merinas’ at a functional level. For being clear, with the Roman concrete we could not make a tenth of the things we do with modern concrete.
The clearest example is reinforced concrete (that is, the mixture of concrete with reinforcement steel). These materials allow us to solve many of the structural problems presented , We have to pay a cost. The most obvious: the structures run before.
We make the concrete we want to do. This is perhaps the most important to consider when we talk about Roman concrete: we do not “concrete to the Roman” because we do not want; Because it is not worth what we want to get. The same potter It puts examples (the Hindu temples and Buddhists built to “last more than 1000 years”) that show that current science and technology allow authentic virguerías. The question is if we want to do them in a world that changes so quickly and not, no matter how much we like the Romans, we do not want.
Luckily: that allows us to go much further.
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Image | Renzo Vanden Bussche
*An earlier version of this article was published in January 2023
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