Mortar mixes with oxblood: historical background, model sample recipes and properties

In this survey we present studies on mortar mixes added with oxblood, which was a commonly found local waste material, with a wide application and long history of use; a precise recipe of lime–pozzolan mortar with blood addition from a 19th-century Italian manual was chosen, and model samples were prepared accordingly, with the aim of better understanding the chemical, mineralogical and physical characteristics of such compositions, starting with a blank reference specimen. The specimens were analysed by means of scanning electron microscopy, infrared spectroscopy, thermal analysis and X-ray diffraction, and the results suggested that amorphous calcium carbonate could be formed in the specimens with oxblood addition. These preliminary results allow a better understanding of historical building practices, measuring effects induced by organic additives on mortar microstructure, as well as an evaluation of new performances obtained in mortar mixes. Moreover, this paper intends to propose a full multi-discipline approach to bridge the history of architecture and building materials to conservation science.