The use of pozzolanic materials in Maya mortars: new evidence from Río Bec (Campeche, Mexico)

The use of pozzolanas to improve the performance of lime mortar is usually regarded as a major contribution of the Greco-Roman civilizations to mortar technology. While this remains unquestioned; recent investigations have shown that this practice was also known in Mesoamerica before the Spanish Conquest. The mortars produced in the Maya lowlands, in particular, have been shown to contain various compounds similar to those formed as a result of the reaction between lime and pozzolanas such as volcanic ash or other siliceous and/or aluminous materials. However, until recently, petrographic studies had failed to present direct evidence that the formation of these compounds was due to the addition of pozzolanas rather than to the use of a natural hydraulic lime. The microscopic analysis of mortar samples from the archaeological site of Río Bec in southeastern Campeche provides this evidence. The identification of pyroclastic material in the form of unaltered glass shards confirms, for the first time, the use of pozzolanic materials in ancient Maya mortars. Furthermore, the analysis suggests the use of other materials that potentially acted as pozzolanas such as phytoliths and argillaceous inclusions. The purpose of this paper is to present these new data and to discuss their significance for the understanding of Maya mortar technology.