FRP-to-masonry bond durability assessment with infrared thermography method

The bond behavior between FRP composites and masonry substrate plays an important role in the performance of externally bonded reinforced masonry structures. Therefore, monitoring the bond quality during the application and subsequent service life of a structure is of crucial importance for execution control and structural health monitoring. The bond quality can change during the service life of the structure due to environmental conditions. Local detachments may occur at the FRP/substrate interface, affecting the bond performance to a large extent. Therefore, the use of expedite and efficient non-destructive techniques for assessment of the bond quality and monitoring FRP delamination is of much interest. Active infrared thermography (IR) technique was used in this study for assessing the bond quality in environmentally degraded FRP-strengthened masonry elements. The applicability and accuracy of the adopted method was initially validated by localization and size quantification of artificially embedded defects in FRP-strengthened brick specimens. Then, the method was used for investigating the appearance and progression of FRP delaminations due to environmental conditions. GFRP-strengthened brick specimens were exposed to accelerated hygrothermal ageing tests and inspected periodically with the IR camera. The results showed environmental exposure may produce large progressive FRP delaminations.Fundação para a Ciência e Tecnologi

Detection of cracks in concrete strengthened with CFRP systems using infra-red thermography

Bond defects due to the development of cracks in concrete strengthened externally with CFRP can degrade the integrity of the composite system. Previous studies have addressed this issue by using different non-destructive testing (NDT) methods, and most have attempted to determine a reliable method to detect cracks and recognize their properties. Infrared thermography (IRT) has emerged as an effective method to detect the propagation of cracks and determine their width in the substrate structure of the composite system. This paper presents the findings of an investigation of CFRP-concrete samples containing various kinds of artificial and loading cracks at the concrete surface. Different types of FRP fabrics and laminate combinations were used in the design. Active IRT was adopted for the thermal observation. Thermal pulses were applied with different angles to enhance crack measurement. The results show that the technique is capable of detecting the location and width of cracks quite adequately. Moreover, the location of the external heating and interval pulse has a considerable effect on crack detection. However, the results show that it is not possible to determine crack depth by using pulsed IRT

Detection of bond defects in CFRP sheets bonded to concrete using infrared thermography

Abstract not available

Infrared thermography for civil structural assessment: demonstrations with laboratory and field studies

A detailed investigation of infrared thermography (IRT) for civil structures is presented by considering different technologies, data analysis methods and experimental conditions in the laboratory and also in the field. Three different types of infrared (IR) camera were compared under active IRT conditions in the laboratory to examine the effect of photography angle on IRT along with the specifications of cameras. It is found that when IR images are taken from a certain angle, each camera shows different temperature readings. However, since each IR camera can capture temperature differences between sound and delaminated areas, they have a potential to detect delaminated area under a given condition in spite of camera specifications even when they are utilized from a certain angle. Furthermore, a more objective data analysis method than just comparing IR images was explored to assess IR data, and it is much easier to detect delamination than raw IR images. Specially designed laboratory and field studies show the capabilities, opportunities and challenges of implementing IRT for civil structures

Systematic review of single and combined treatments for different types of striae : A comparison of striae treatments

Acknowledgements The authors would like to express their gratitude to the staff of Rasool Akram Medical Complex Clinical Research Development Center (RCRDC) for their technical and editorial assistance.Peer reviewedPostprin