Ceramic Pipes of the Roman Aqueduct from Raiano Village (L’Aquila, Italy): A technological Study

Roman aqueducts are an example in which material knowledge and engineering skills melt together to create extraordinary architectural works that have been survived in the centuries. Even if Roman aqueducts reflect the engineering knowledges of the past, very few archaeometric works took into account these artworks in Europe or in Italy. Considering this gap in the scientific studies, this work is focused on the study of ceramic pipes of the final part of the Uccole Roman aqueduct built in the 1st century AD by the Romans between the Subequana Valley and the Sulmona Plain (Abruzzo, Italy). A multi-analytical approach consisting in optical microscopy, scanning electron microscopy and X-ray powder diffraction was applied to investigate the technological background and to reconstruct the provenance of the raw materials involved in the production. Petrographic and mineralogical results suggest the presence of one petrographic fabric produced using an illitic clay with fine inclusions of quartz, K-feldspar and micas and a coarse fraction mainly composed by fragments of volcanic, sedimentary calcareous and siliceous rocks. The analysis of the grain size distribution and the shape of inclusions suggest a careful selection of the material with the addition by manufacturers of the coarse grain inclusions to create a strong material. The mineralogical assemblage indicates a firing temperature in the range 700-800 °C, in oxidizing conditions. The presence of fragments of basic volcanic rocks as inclusions suggests the supply of the raw materials from a local pyroclastic deposit. These results underline that the use of volcanic ashes in architectural works was not limited to Rome and during the conquest of Abruzzi territories by the Romans, the local populations were influenced by their technological skills.