Experimental study of the bond interaction between CFRP and concrete under blast loading

• Published in: Composite structures 2021-12, Vol.277, p.114608, Article 114608
• Main Authors: Maazoun, Azer, Matthys, Stijn, Belkassem, Bachir, Atoui, Oussama, Lecompte, David
• Format: Article
• Language: English
• Subjects: Blast loading; Bond shear test; Carbon fiber reinforced polymer CFRP; Concrete prism; Debonding process; Dynamic stresses
• ISSN: 0263-8223; 1879-1085
• DOI: 10.1016/j.compstruct.2021.114608

•Increasing the bond length of the CFRP strips adds stiffness to the specimens and increases the strain distribution in the CFRP strips by taking part of the blast energy.•The concrete strength of the concrete prism is enhanced due to the strain rate effect and cracking runs through aggregates in the concrete prism.•Under blast loading, the propagation of the blast wave through the concrete prism generates vibrations in different directions and increasing the bond length of the CFRP strip reduces the frequency of the out of plane vibration. Specific to blast loading, bond shear tests between carbon fiber reinforced polymer (CFRP) strips and concrete have not yet been reported in literature, to the best knowledge of the authors. Given the high potential of strengthening concrete with CFRP to increase blast resistance, it is necessary to better understand the dynamic interaction between concrete and CFRP under blast impulse. This article presents a new experimental setup developed in order to study blast driven bond interaction between CFRP and concrete. An evaluation of the bond at the interface between the CFRP strip and the concrete is conducted in order to identify the parameters that affect the bond strength under blast loading. Several retrofitted specimens with different bond strength are tested. An explosive driven shock tube (EDST) set-up is used to generate the blast loading. Piezo resistive strain gauges and digital image correlation (DIC) measurement are used to record the debonding process and the evolution of the strain along the bonded area. As such, the bond behaviour is studied for three different bond lengths and the effect of interaction of the blast wave within the concrete is highlighted. The experimental tests demonstrate that under blast loading, the debonding between the CFRP strip and the concrete occurs due to a combined effect: interface stresses caused by the induced force in the CFRP and additional stresses resulting from the propagation of the blast induced stress wave within the concrete.