Single-lap shear tests of textile reinforced mortar retrofit systems bonded to masonry: revealing the fracture progress by digital image correlation and acoustic emission

Among the plethora of techniques that exist for the strengthening of historical and modern masonry structures, particularly textile reinforced mortar (TRM) has been the subject of recent research. TRM offers several advantages over traditional strengthening techniques. However, its debonding behavior at the masonry-to-TRM and/or textile-to-mortar interfaces is crucial for an effective repair, an issue that has not been adequately investigated. Therefore, non-destructive (NDT) techniques are considered for characterizing the bond efficacy and further understanding the damage progression on TRM. An experimental set-up incorporating acoustic emission (AE) and digital image correlation (DIC) techniques was designed. The results were processed according to the recommendation set forth by RILEM TC 250-CSM. With an integrated monitoring setup, it is possible to continuously track and characterize the damage progress in specimens with different material combinations and test set-up variations. DIC and AE were successful in providing 3D cracking and debonding localization and in distinguishing different failure mechanisms. Additionally, sensitive AE parameters were found to differentiate between damage, dormant periods and load drops induced by setup limitations and not by damage. The incorporation of NDT inspection on shear bond tests proposed by RILEM TC 250-CSM provide further understanding into the debonding behavior of TRM strengthened masonry structures.