Experimental characterization of carbon-fiber/concrete adhesive interface for retrofitting of concrete bridge structures

Abstract

ABSTRACT The modes I + II fracture behavior of the adhesive interface between concrete and carbon fiber sheets was investigated on the basis of the linear fracture mechanics. The mixed mode disk specimen was proposed to evaluate the mixed mode energy release rate of the adhesive interface. The evaluation formula for the energy release rate was also derived and its validity was studied on the basis of the results of finite element analysis. The numerical results indicated that the theoretical formula was not valid for evaluating the absolute value of the energy release rate though it could well describe the dimensional tendency between the energy release rate and geometric parameters of the specimen. Hence, it was concluded that the combination of finite element analysis and theoretical prediction was necessary to evaluate the energy release rate with high degree of accuracy. The mixed mode fracture toughness test of an acrylic resin adhesive interface was carried out by applying the present method. The mode II fracture toughness was more than twice as high as the mode I fracture toughness. However, those values were much lower than the fracture toughness of the adhesive resin itself, because the locus of failure was microscopically not in the interface but in the concrete. The mixed mode fracture toughness followed the linear fracture criterion; the principle of superposition was valid for the present specimen.