> the romans supposedly used a superior cement which we can no longer replicate. I read a few years ago the 'secret' had been discovered and it was to do with

> the romans supposedly used a superior cement which we can no longer replicate. I read a few years ago the 'secret' had been discovered and it was to do with volcanic ash which made it self healing. Doing a quick search there seems to be a lot of articles from 2014 about this so possibly that what when the research was published. https://archserve.id.ucsb.edu/courses/arthistory/152k/concrete.html https://archserve.id.ucsb.edu/courses/arthistory/152k/concre... https://www.ibtimes.co.uk/why-pantheon-has-not-crumbled-roman-concrete-mortar-used-secret-ingredient-that-could-reduce-1479938 https://www.ibtimes.co.uk/why-pantheon-has-not-crumbled-roma... http://www.pnas.org/content/early/2014/12/10/1417456111 http://www.pnas.org/content/early/2014/12/10/1417456111