Natural Brick of Viminacium

Abstract

Building activity in Viminacium, an important Roman legionary fortress and a city on the Danube in today’s Serbia, was influenced by its natural surroundings. They influenced the position and orientation of the first fortification, built in the 1st century AD, as well as the range of raw materials for the construction of buildings in all of Viminacium’s life phases. The first building material along with wood that Romans encountered after coming to the northern edge of the Stig Plain must have been red burnt soil created by coal combustion, whose source is only a few kilometres from the fortress. The first ramparts were constructed using blocks made of this material, called "crvenka" by the local people, which was used for building purposes in the wider area until relatively recently. It is very well known that manmade brick was used as an artificial material with pozzolanic features added to Roman lime mortars. Viminacium was a provincial centre of brick production, using local soil as a raw material. Since crvenka can be recognised as a kind of “natural brick” made of local sediments, an assumption was made that it could also have been used in Viminacium lime mortars as a natural pozzolanic addition. After laboratory research of its mineralogical, mechanical, physical, and chemical characteristics, crushed and ground crvenka was mixed with lime. Mortars with excellent mechanical properties were created, offering us one of the indicators of their possible hydraulicity. With the knowledge of the firing temperatures that could have been developed in Roman brick kilns, this research will be continued. An attempt to determine the temperature that red ceramic fragments, visible in the composition of Viminacium mortars, were fired at, will be made, leading us further towards their possible characterisation as artificial or “natural” brick.