Crushed Terracotta for Cocciopesto, Coarse and Fine

Broken pottery, tile or brick, crushed and mixed with lime, made the Roman waterproof mortar opus signinum (cocciopesto), used for baths, aqueducts and cisterns. Pliny says the broken pottery was beaten to powder. Crush fired brick or tile and sieve it into a coarse grade and a fine powder. The picture: a fragment of Roman pavement, broken pottery set in lime.