Opus signinum

It is a form of Roman concrete (opus caementicium), the main difference being the addition of small pieces of broken pot, including amphorae, tiles or brick, instead of other aggregates.

[1] Its main advantage over opus caementicium was that it is waterproof, the reason for its widespread use in Roman baths, aqueducts, cisterns and any buildings involving water.

Pliny the Elder describes its manufacture:[2] Even broken pottery has been utilised; it being found that, beaten to powder, and tempered with lime, it becomes more solid and durable than other substances of a similar nature; forming the cement known as the Signine composition, so extensively employed for even making the pavements of houses.Pliny's use of the term signine references Signia (modern Segni), the town in Latium which was famous for its tiles.

[5][6] Floors of signinum are found extensively in the Punic towns of North Africa and commonly in the Hellenistic houses on Sicily.

[9] The trend began in the 1st century BC, proliferating in private homes as well as public buildings.