Latest Theory on Roman Concrete: Hot Mixed Quicklime

The recent discovery of calcite-filled cracks in Roman concrete (29) suggested a potential long-term healing process that requires a Ca-rich source. Considering the ubiquity of relict lime clasts in Roman concrete (5, 12, 24, 43) and their high surface area due to their particulate microstructure (Fig. 4, A to D), these inclusions might provide the requisite Ca reservoirs for these processes. Inspired by these observations, we set out to create a modern analog of this material and explore its properties. Considering the relatively even distribution of the lime clasts and their well-defined morphologies, these observations raise the intriguing proposition that they may have been added to the concrete mix in their intact form (a practice known as hot mixing). Considering the documented use of hot mixing in both ancient and modern mortar preparations (19, 44), we explored this approach in our synthetic formulations.



Two implications for better concrete:

  1. Use quicklime instead of hydrated lime:
  1. Add pozzolan:

Thanks for elucidating. CT kind of left us hanging.

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