Roberto Bugini

Monomineralic Aggregates in Mortars: Examples From Lombardy (Northern Italy)

Scientific analyses were carried out on mortar samples sourced from heritage buildings of Lombardy dating from fifteenth to nineteenth century (Milan, Como, Mantua etc.). The methods employed were optical microscopy on thin section and X-ray diffraction on powder. The mortars in Lombardy were generally made of lime or gypsum (binder) and sand, rock or brick fragments (aggregate), but an interesting character, especially marking the stuccoes, is the use of a monomineralic aggregate made of calcite or quartz grains. The calcite is present in two forms: subrounded polycrystalline and angular monocrystalline grains; these features are related to the crushing of marble (polycrystalline) or of calcite veins (monocrystalline). The quartz is also present in two forms: polycrystalline and monocrystalline grains with angular boundaries; in this case, the features are related to the crushing of metamorphic rock (gneiss).

Tecniche e materiali da costruzione nella Milano antica e medievale

The city of Milan preserve an amazing historical and architectural heritage, consisting of a high number of ancient churches, in most cases built to the origins of Christianity and transformed into new form during the Romanesque. In the article are synthetically presented the results of the research work of the writer about construction techniques of the most important churches in the city (S. Ambrogio, S. Simpliciano, S. Giovanni alle Fonti, S. Nazaro Maggiore, ...), trying to highlight the main changes between Late Antiquity and Romanesque. A large amount of stone material were used in Roman architecture of Milan and Lombardy, thanks to the geological variety of the territory. The Alps supplied granites, diorites, gneisses and marbles; the Prealps supplied limestones, dolomites, sandstones (Mesozoic) and conglomerates (Quaternary); the Padania alluvial plain supplied pebbles, gravels, sands and clays (Quaternary). Each stone had a local use reaching the nearest towns (Como, Pavia, Milan, Bergamo, Brescia) through waterways; the towns of the plain (Piacenza, Cremona, Mantua) employed bricks made of local clay. Milano, the capital, employed also stones coming from abroad (limestones from Venetia and Friuli). White marbles of Apuanian Alps and coloured marbles of Eastern mediterranean were also diffused in Milan and other Lombard sites despite the laborious supplying. The stones quarried by the Romans were continuously used in the following centuries.