First results using Digital Image Correlation for deformation field measurements in laboratory tests on Textile Reinforced Mortar (TRM)-strengthened masonry panels

The Digital Image Correlation (DIC) technique is a non-contact, full-field optical method and a non-destructive evaluation approach that enables the measurement of displacements and strain fields across an entire surface during experimental tests. This technique provides high-resolution data, enabling the measurement of global strain, the detection of localized strain concentrations and crack initiation, and monitoring the evolution of dominant damage mechanisms. DIC’s ability to capture both in-plane and out-of-plane displacements makes it a powerful tool for detailed structural assessment. This paper presents preliminary results on the application of the DIC technique during diagonal compression tests of 1.2 x 1.2 x 0.25 m³ unstrengthened and strengthened clay brick masonry panels. The strengthening system consists of two Textile Reinforced Mortar (TRM) layers applied on both wall sides and connected by helical stainless-steel connectors. Glass fiber bidirectional fabrics are used as TRM reinforcing meshes, embedded in a 30 mm thick lime-based mortar. A couple of CMOS cameras were used to apply the stereo-DIC algorithm and record the three-dimensional displacement field during test execution. The displacement field obtained through DIC has been compared and validated with that obtained through the more common analog Linear Variable Differential Transformers (LVDT). The comparison highlighted the benefits and weaknesses of the DIC technique.