New evidence of early use of artificial pozzolanic material in mortars

Hydraulic building composites, such as mortars and plasters, produced with artificial pozzolanic materials, became widely popular thanks to the Romans. Reports on earlier uses of such composites can also be found, mainly in archaeological and historic documents. These date back as far as the time of Minoan and Mycenaean civilizations. Here, we present a holistic analytical investigation of Late Bronze Age mortars from various archaeological sites of Cyprus. We focus on petrographic observations of thin sections, scanning electron microscopy and energy dispersive X-ray microanalyses and we investigate the microstructure and texture of the samples and the chemical composition and interface of their binders. Results of powder X-ray diffraction analyses are also presented, alongside a series of measurements using mercury intrusion porosimetry and vacuum saturation, aiming to estimate the pore size distribution and the physical properties (i.e. open porosity and bulk density) of the specimens under investigation. We also report on tests carried out to assess the drilling resistance of the mortars using a novel, portable system. The results thoroughly confirm, for the first time, the earliest intentional use of crushed brick as an artificial hydraulic additive in lime mortars in Cyprus, in order to enhance their performance and longevity in the absence of natural pozzolanas.