Application of digital image correlation to compression tests on tuff masonry panels strengthened by textile reinforced mortar

Digital image correlation (DIC) is a contactless full-field optical technique for measuring displacements that can be potentially used in place of more common linear variable differential transformers (LVDTs) to avoid instrumentation damage during destructive tests. However, despite being already adopted in several fields, its potentialities in testing full-scale masonry walls strengthened with textile reinforcing mortar (TRM) have not been fully investigated yet. In this paper, the results obtained by applying a stereo-DIC technique to compression tests of unstrengthened and TRM-strengthened tuff masonry walls (1.0 x 1.2 x 0.25 m(3)) are reported. Results showed that the presence of helical steel bars used to connect the two TRM layers caused crack localisation to the masonry wall, leading to a reduction of compression strength. Compared with the results obtained with LVDTs, the DIC technique was able to accurately monitor tridimensional displacements and cracking pattern evolution. The potentialities and limits of this technique are finally highlighted.