Mortar analysis of historic buildings damaged by recent earthquakes in Italy

The paper presents an experimental study on mortar samples taken from historic and monumental buildings damaged or collapsed following the seismic events in Central Italy (2016-2017). Sixty-one samples were analysed via a set of diagnostic investigations to characterize the mortar and correlate it with the performance of the masonry. The techniques used were: X-ray diffraction, scanning electron microscopy and microanalysis, differential scanning calorimetry, calcimetry, Fourier-transform infrared spectroscopy, soluble salt analysis by conductimetry and dosage of anionic species by ion chromatography, particle-size analysis, direct shear. Microstructural characterization of the mortars revealed differences in mortar composition depending on their provenance. In particular the samples from Norcia contained large quantities of calcite while in the mortars from Pretare, dolomite was identified. In the case of Amatrice, only a few samples showed crystalline phases and compounds ascribable to binders. These results were largely confirmed by the other chemical and physical analysis performed, and mechanical tests also demonstrated low cohesion. The tests showed that in almost all the samples, poor quality mortars were used, and, in some cases, underachieving binder mortar.