Lime preparation in ancient Roman architectural and marine mortars

Summary

Romans prepared lime for the volcanic ash mortars of conglomeratic concretes using methods (Vitruvius, de Architectura 5.1.2-3) that are reflected in modern Italian lime industry terminology. In mortars of architectural concretes in Rome (1st C BCE–3rd C CE) builders mixed quicklime with freshwater to form stiff putty (grasello di calce) and then incorporated moistened scoriaceous ash, shown by an experimental reproduction. Pure calcite in unburnt particles (incotti) suggests pre-orogenic Jurassic-Cretaceous limestone of the Monti Sabini 30km northeast of Rome, rather than syn- and post-orogenic Cenozoic carbonate deposits with detrital silicate minerals. High calcium lime (94 wt% CaO) was likely calcined at the quarry; no marine limestone aggregate occurs in the concretes. In mortars of maritime harbor concretes (1st C BCE–2nd C CE) drilled by ROMACONS, builders used fine sand- to gravel-sized lime (zolle or greggio di calce) mainly calcined from local limestone, with high calcium compositions (Portus, Pozzuoli Bay), mixed calcic and dolomitic compositions (Cosa, Anzio, Egnazia, Caesarea, Alexandria) and, rarely, argillaceous compositions (Chersonessos). The lime was likely aged in freshwater (calce spenta e maturata), mixed in a trough with pumiceous ash, and submerged in submarine forms. Carbonate rock is the predominant aggregate of eastern Mediterranean harbor concretes.

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This Resource is Part of the Following Collections

• The Exploitation of Limestone in Ancient Mesoamerica   •
• Society for American Archaeology 80th Annual Meeting, San Francisco, CA (2015)

Keywords

Spatial Coverage