The durability of ancient Roman structures has long been a mystery to scientists who have sought to determine how early concrete endured for over two millennia. A new study resolves the enigma, focusing on an inclusion (often disregarded as a byproduct) that allows Roman concrete to repair itself: chunks of material referred to as lime clasts. Scientists have found that the clasts are made up of calcium carbonate formed at a high-temperature, most likely by adding a more reactive form of lime called quicklime. This makes the composition brittle, enabling cracks that occur in the concrete to move through the lime clasts easily. Then, when water mixes into these cracks, it forms a solution that hardens back into calcium carbonate, sealing the gap. By re-creating this quicklime concrete and comparing its strength to modern materials, the authors of the study now seek to use their findings to develop stronger commercial concrete. Learn more at New Atlas.
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