Application of acousto-ultrasonic technique in evaluation of bond strength between composites and concrete substrates.

摘要

The use of fiber reinforced polymer materials (composite FRP materials) to strengthen existing concrete structures continues to expand as our current infrastructure ages. However, one of the concerns when using FRP systems in this manner is the difficulty in determining the quality and strength of the bond between the concrete and FRP overlays. There appears to be a need for a reliable non-destructive testing (NDT) method that can directly determine the strength of this bond to ensure the structural performance of FRP-strengthened concrete systems.;The goal of this research was to evaluate whether a non-destructive acousto-ultrasonic parameters (AUP) evaluation method could be used to determine the shear strength of the bond between FRP systems and concrete substrates. Eighteen concrete beams were externally reinforced flexurally with carbon fiber reinforced polymers (CFRP) and glass fiber reinforced polymers (GFRP) and then non-destructively tested using the AUP procedures. The test beam specimens were then placed in a simply supported configuration and loaded to failure. Interfacial shear strengths obtained from the destructive testing were compared against AUP analysis results to determine if a correlation could be established.;Both longitudinal and shear transducers were utilized to collect propagating stress waves; however, only the longitudinal transducer provided consistent correlations to interfacial shear strength values. The investigation concluded that the (AUP) analysis procedure can be used to determine the interfacial shear bond strength of both glass and carbon fiber reinforced concrete beam specimens with relatively good correlation to actual strength data.