Chemical–mineralogical characterisation as useful tool in the assessment of the decay of the Mesola Castle (Ferrara, Italy)

The Mesola Castle and its Portico (16th century) rises on the right side branch of the River Po Delta in the eastern part of Ferrara province (Italy). Bricks, mortars and plasters from the Castle’s Portico were characterised by optical microscopy, X-ray fluorescence, X-ray diffraction and scanning electron microscopy/energy-dispersive X-ray spectrometers. This masonry is affected by efflorescence and sub-efflorescence, and mineralogical analysis, together with scanning electron microscopy observations, assisted to define the damaging products. Structures built in coastal environments are subject to sea weathering which cause substantial damages mainly due to the presence of salts. These could attack the building materials: (a) by penetrating from the ground through dampness; (b) carried by the wind in the form of salt spray; (c) due to occasional or recurrent flooding; (d) caused by the use of marine water during the preparation of mortar. For these reasons an integrated study approach involving chemical–mineralogical analysis and assessment of the environmental conditions is a useful tool to better define the causes of building materials deterioration.