The discovery of pozzolanic properties of calcined clays in the late 1700s in France and the technologies associated with its activation

The current trend towards the use of calcined clays as supplementary cementitious materials might lead to the feeling that this technology is a recent development. However, the description of their pozzolanic properties, along with the ways to burn them correctly, dates back from the first half of the nineteenth century, within the industrial revolution– the preliminary idea was even published in 1787. In France, the famous chemist Louis Vicat made seminal descriptions of the type of clays involved and understood the chemistry behind the phenomenon. It gave rise to the use of the term “artificial pozzolan”.