Chemists Have Recreated Long-Lasting Roman Concrete | Chemistry And Physics (2024)

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Chemists Have Recreated Long-Lasting Roman Concrete | Chemistry And Physics? ›

The blocks of concrete were broken in half, and then water was trickled through the cracks. What the team observed was astonishing! The blocks created through the hot mixing process healed within two to three weeks, whereas the traditional concrete never healed.

Using new information gathered by infrared cameras and other microarchaeology methods on samples taken from ancient concrete in central Italy, the group was able to recreate their own “Roman concrete” and witnessed their samples make inflicted cracks disappear in a matter of weeks.

The research team discovered that while modern concrete is made to be inert, the Roman version interacts with the environment. When seawater interacts with the mixture, it forms rare minerals aluminous tobermorite and phillipsite which are believed to strengthen the material.

Why do chemists want to understand how the ancient Romans made concrete? Chemists want to improve modern concrete production. The concrete made by the ancient Romans has lasted much longer than concrete made nowadays.

Young cement built using a Roman recipe would probably not have the compressive strength to handle modern use — at least not initially. But that doesn't mean concocting a concrete mix using Roman engineering savvy wouldn't be useful.

Roman concrete, in many cases, has proven to be longer-lasting than its modern equivalent, which can deteriorate within decades.

The believed the key to replication was a process called “hot mixing.” In this process, dry granules of calcium oxide – or quicklime – are mixed with volcanic ash to make the cement, and then water is added.

By 200 B.C.E., concrete was used in the majority of their construction projects. Roman concrete consisted of a mixture of a white powder known as slaked lime, small particles and rock fragments called tephra ejected by volcanic eruptions, and water.

Modern concrete—used in everything from roads to buildings to bridges—can break down in as few as 50 years. But more than a thousand years after the western Roman Empire crumbled to dust, its concrete structures are still standing.

A calcium-rich lime clast (in red), which is responsible for the unique self-healing properties in this ancient material, is clearly visible in the lower region of the image. The hot mixing allows lime clasts—characteristically brittle nanoparticulate, an easily fractured and reactive calcium source—to develop.

What is the biggest problem with Roman concrete? ›

It was a formidable tool of Roman engineering know-how. Yet, for all its advantages, concrete had one major defect: it was unsightly. Once the wooden formwork was removed, it showed an ugly surface. In the beginning, its use was mainly restricted to substructures where noone would see it.

It also has a reduced environmental footprint due to its lower cooking temperature and much longer lifespan. Usable examples of Roman concrete exposed to harsh marine environments have been found to be 2000 years old with little or no wear.

We were taught that the answer to the question is that modern concrete has steel reinforcing in it, and Roman concrete didn't. Simply put, reinforcing rusts and expands, cracking the concrete, allowing more water in, more rust, and more concrete destruction.

There's a new paper out exploring some of the chemical mechanisms at work in Roman concrete. As per usual, it's triggered a round of enthusiastic discussion of Roman concrete, and how its ability to last for millennia puts modern concrete (which often fails after a few decades) to shame.

In a recent study, scientists have got closer to the answer—and their findings could reverberate long into the future. Not only is Roman concrete exponentially more durable than modern concrete, but it can also repair itself.

Many of these structures were built with concrete: Rome's famed Pantheon, which has the world's largest unreinforced concrete dome and was dedicated in 128 C.E., is still intact, and some ancient Roman aqueducts still deliver water to Rome today.

During the Middle Ages, the history of concrete crept backward. After the fall of the Roman Empire in 476 AD, the technique for making pozzolan cement was lost until the discovery of manuscripts describing it was found in 1414. This rekindled the interest in building with concrete.