According to a new study, seawater is one of the key elements in the longevity and strength of ancient Roman concrete. This came as quite a surprising fact, seeing as, in most cases, such water is an erosive and corrosive factor.
The latest research on the matter was conducted by a group of US and Chinese scientists. These published their results on ancient Roman concrete in a paper in the journal American Mineralogist.
Ancient Roman Concrete Strengthened by the Destructor of Modern Cement
Research shows that Romans created their concrete out of a mix of three major elements. These were lime (calcium oxide), volcanic rock and ash, and also seawater. The composition was further strengthened by the addition of volcanic materials.
Modern researchers were able to determine this composition by using advanced techniques such as Raman spectroscopy and also X-ray micro-diffraction. These also helped take a closer look at the same mixture.
The research team was able to identify and study the crystals of two types of minerals. One is the more common phillipsite, a porous material, and the other is the rare aluminous tobermorite. Scientists believe that these crystals were able to grow inside the ancient Roman concrete thanks to the action of seawater.
As this carved inside the cement, the crystals were able to form structures and fill and reinforce the empty places.
“Contrary to the principles of modern cement-based concrete, the Romans created a rock-like concrete that thrives in open chemical exchange with seawater,” stated Marie-Jackson, the lead author of the study.
Modern concrete is composed of “aggregates” or particles of crushed rock or sand bound together by cement. Chemical changes or the action of the erosive seawater can expand and weaken such compositions.
Now, the research team will be looking to try and recreate a sort of ancient Roman concrete. They will be doing so by replacing their base composition with modern materials, as volcanic ash and rocks are hard to find.
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