Technology of Medieval Mortars: An Investigation into the Use of Organic Additives

• Published in: Archaeometry Vol. 58; no. 1; pp. 115 - 130
• Main Authors: Rampazzi, L., Colombini, M. P., Conti, C., Corti, C., Lluveras-Tenorio, A., Sansonetti, A., Zanaboni, M.
• Format: Journal Article
• Language: English
• Published: Oxford Blackwell Publishing Ltd 01-02-2016; Wiley Subscription Services, Inc; Wiley
• Subjects: Additives; Amalfi; Analytical chemistry; Archaeology and Prehistory; Chemical Sciences; gas chromatography - mass spectrometry; Humanities and Social Sciences; infrared spectroscopy; Life Sciences; medieval mortars; microscopic analyses; mortar technology; organic additives; thermal analysis; mortar technology; Amalfi; medieval mortars; microscopic analyses; organic additives; gas chromatography – mass spectrometry; infrared spectroscopy; thermal analysis
• ISSN: 0003-813X; 1475-4754
• DOI: 10.1111/arcm.12155

This work proposes a multi‐analytical approach to determine the additives in historical mortars, the use of which is widely described in bibliographical sources, but has rarely been reported in the literature. A protocol to thoroughly analyse mortars was created (optical microscopy, X‐ray diffraction, infrared spectroscopy, thermal analyses and gas chromatography – mass spectrometry). These techniques, which had already been carried out on samples from various sites from the Roman to the modern era, determined that additives had only been used in the mortars from the internal masonry at our sampling site: the medieval military shipyard of Amalfi (Italy). The investigations yielded information on the production technology, and FT–IR and GC–MS revealed a saccharide material‐based additive in the mortars, of plant origin. The FT–IR spectra suggested the presence of a natural gum, which has been used since ancient times to strengthen the cohesion properties of mortars and their resistance to tensile stress.