The Role of Brick in Hydraulicity of Viminacium Mortars: Decorative Mortars from the Thermae

Abstract

The hydraulicity of the Viminacium mortars is still somewhat unknown, but with laboratory analyses, performed on a small number of samples, and similar research performed worldwide, some conclusions can be drawn. These bring us closer to this topic, which again contribute to our becoming acquainted with the Viminacium building materials, their usage, behaviour in constructions and their mutual relationships. Throughout history, artificial products of soil, specifically bricks and ceramics, represent some of the most commonly used materials with pozzolanic features in the creation of hydraulic lime mortars. In accordance with their function, the Viminacium thermae represent a place with high levels of humidity in the air and water in a large number of rooms, thereby representing a suitable example for analysing the use of hydraulic mortars, which above all needed to be waterproof. This was achieved with the use of bricks, a material produced locally in Viminacium. Fragmentarily preserved remains of wall paintings from the Viminacium thermae are not only numerous and various, but they spatially also include almost all parts of the building. This paper includes the remains of decorative mortars discovered during archaeological research in 2004 and 2007 that had bricks in their structure, which was confirmed with a visual review of mortar cross-sections when brick was used in fragments. It was also suspected due to the reddish colour of some of the layers, most likely connected to the use of brick dust.