1. Ancient Roman concretes have survived for millennia, but the mechanisms behind their durability remain a mystery.
2. A multiscale correlative elemental and chemical mapping approach was used to investigate relict lime clasts associated with ancient Roman mortars.
3. This research suggests that the Romans employed hot mixing, using quicklime in combination with slaked lime, to create a mortar matrix that retained high surface area aggregate-scale lime clasts.
The article is generally reliable and trustworthy as it provides evidence for its claims through detailed analyses of relict lime clasts associated with ancient Roman mortars. The authors also provide evidence for their proposed mechanism of hot mixing by testing modern lime clast–containing cementitious mixtures and demonstrating their self-healing potential. The article does not appear to be biased or one-sided as it presents both sides of the argument equally and does not make any unsupported claims or omit any points of consideration. Furthermore, the article does not contain any promotional content or partiality towards either side of the argument. The article does note possible risks associated with its proposed mechanism, such as environmental consequences due to increased CO2 emissions from cement production, which is important for readers to consider when evaluating the reliability of the article's claims.