Archaeological and Chemical Investigation on Mortars and Bricks from a Necropolis in Braga, Northwest of Portugal

Abstract

This investigation intends to study and characterize the mortars and bricks from walls and floors used in the funerary nucleus of the archaeological site of Dr. Gonçalo Sampaio Street (Braga, Portugal), associated with the Via XVII necropolis of the Bracara Augusta Roman city. The diversity of the funeral structures and their exceptional state of conservation make this sector of the necropolis an unprecedented case and a reference site in the archaeology of Braga, a determinant for its conservation and musealization. Nineteen mortars samples were analysed by X-ray Fluorescence. The results showed clear chemical composition differences among coating and floor mortars (CFM), masonry mortars (MM) and bricks (B) groups of samples. The chemical affinity between CFM from the V to IV centuries, CFM from the IV to V centuries, MM from brick walls (IV–V centuries), MM from stone walls (V–VII centuries) and B from the IV to V centuries samples were confirmed by statistical analyses. Their composition was distinctly related to the use of different raw materials, according to their chronological context; in mortars, according to their function in the structures; and in some samples, from contamination.

Interpretation of Funerary Spaces in Roman Times: Insights from a Nucleus of Braga, NW Iberian Peninsula

“…Concerning the constructive and material aspects of this building, studies are currently ongoing regarding the chemical and mineralogical characterization of the mortars using X-ray diffraction (XRD), X-ray fluorescence (XRF), and scanning electron microscopy (SEM) of the walls, as well as the coatings made with opus signinum. These studies are being performed by a multidisciplinary team from the University of Minho and the University of Aveiro, and show some similar aspects to other preserved archeological sets (N.A.1) in Bracara Augusta, a burial area of the Via XVII necropolis, which consists of five burial graves, and a rectangular enclosure (Figure 3), and is also in the process of musealization (Fragata et al 2021;Ribeiro 2013).…”

The Architectural Terracotta Marks of Bracara Augusta (Braga, Portugal): A First Typology Classification

“…Future work on the mineralogical and chemical characterization of ATC, under development and already applied by our team in the context of ancient mortars [42,43], could give more information on the raw materials used, namely their provenance, as well as the manufacturing process, workshop organization and production distribution. These characterization analyses could be linked with stratigraphy, allowing a deeper contextualization, which might lead to the development of further chronotypologies.…”

Special Issue of “Material Analysis in Cultural Heritage”

“…Two papers deal with masonry and architectural remains. Fragata et al [ 9 ] describe bricks and mortars in the Roman city of Bracara Augusta, modern-day Braga in Portugal. Chemical/elemental analysis performed by XRF demonstrates that the composition of the bricks differs according to their functionality, depending on whether they are being used as coatings, floorings, or masonry mortars, and their age of origin between the 4th and 7th centuries.…”