Mortar samples from the Notre-Dame Cathedral at Tournai in Belgium have been investigated as part of a broader study considering the transition of ancient cities and their rural territories from Roman to late Roman society and the transformation to the early Middle Ages. Masonry mortars and mortars used for flooring have been studied from the Imperial Roman period, the Carolingian style period and the Romanesque style period (4th–11th century AD).
A selected set of samples has been characterised using a combination of mineralogical, chemical and microscopical techniques. This characterisation enabled us to refine our knowledge of the mortar composition, of the original materials and of their provenance. It appears that both chalk and “hard” Tournaisian limestone were used to produce the lime. Both locally available materials can yield either hydraulic or non-hydraulic lime. The aggregates have a local origin. Additionally, several microscopical techniques were applied to identify the nature of the overburnt particles. The low abundance of this type of Binder Related Particles in the Gallo-Roman and Palaeo-Christian mortars suggests that technological knowledge, be it empirical or theoretical, was available.