Roman cement is a substance developed by James Parker in the 1780s, being patented in 1796.[1][2]
The name is misleading, as it is nothing like any material used by the Romans, but was a "natural cement" made by burning septaria – nodules that are found in certain clay deposits, and that contain both clay minerals and calcium carbonate. The burnt nodules were ground to a fine powder. This product, made into a mortar with sand, set in 5–15 minutes.[1][2][3] The success of Roman cement led other manufacturers to develop rival products by burning artificial mixtures of clay and chalk.[1][4][5]