Microstructure of Two-Thousand-Year Old Lightweight Concrete

This study is a continuation of a series dealing with the composition and properties of lightweight concrete developed 2000 years ago by the builders of an ancient culture, the Totonacas. The concrete was found in the main city of the Totonacas, "El Tajin", near the modern city of Veracruz in Mexico. The lightweight concrete was used to construct flat slabs in the pyramidal buildings which were found by accident by Mexican researchers. This paper presents a review of the developments leading to modern cements made by the Greek and Roman civilizations and compares these developments with the develpments made independently in Mesoamerica. The properties of the concrete studied are: the nature of the interfacial zone, the microstructure and composition of the mortar phase and the aggregates used. Microstructure is characterized by morphology, porosity and pore size distribution. These properties are compared with the properties of a concrete of approximately the same age which was found in Camiros Greece.