Roman cement

Roman cement is a substance developed by James Parker in the 1780s, and finally patented in 1796.

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. The success of Roman cement led other manufacturers to develop rival products by burning artificial mixtures of clay and chalk.

History

There has been recent resurgence of interest in Natural cements and Roman cements due mainly to the need for repair of façades done in this material in the 19th century. The major confusion involved for many people in this subject is the terminology used. Roman cement - was originally the name given, by Parker, to the cement he patented which is a Natural cement (i.e. it is a marl (or limestone containing integral clay) dug out of the ground, burnt and ground to a fine powder).