Correlation between destructive and non-destructive testing of composite-concrete bonds

In order to reduce chemical leakage in Civil Engineering structures, EDF set a strategy which consists in depositing composite covering on concrete walls. The quality of the composite-concrete bond, as well as its durability during the structures life, are controlled using a destructive technique based on ultimate tensile strength measurements. The purpose of the current study is to propose an alternative non-destructive technique, based on the propagation of ultrasonic wave modes guided along composite-glue-concrete assemblies. A numerical model is first used to simulate the propagation of waves along this layered medium, and to show the existence of a specific mode, namely the "type Rayleigh" mode (TR), the velocity of which is sensitive to the bond quality. Measurements of this velocity for three levels of bond quality then allow mechanical properties of the bonds to be estimated. Changes in these properties, measured in dynamic regime, follow those of the ultimate tensile strength measured in quasi-static regime, for the three qualities of bonding.