Concrete delamination detection using the impulse response method

Abstract

Betongdelaminering er en type indre defekter som påvirker betongkonstruksjoner og forårsaker en separasjon i lagene i betongen som forårsaker et indre tomrom. Hvis det ikke oppdages, kan delaminering føre til at strukturen taper mekaniske egenskaper. Hensikten med denne oppgaven er å utvikle programvare som automatisk oppdager delaminering i betongkonstruksjoner. I den eksperimentelle delen ble kunstig delaminering simulert med 3D-printede elementer plassert inne i betongplatene på forskjellige dybder. Resultatene fra eksperimentene er representert ved bruk av impulsresponsmetoden med et mobilitetsplott.

Concrete is known for being a reliable construction material for building all kind of structures. Nevertheless, internal defects such as delamination can reduce significantly the service life of concrete. Delamination is a type of internal defect that affects concrete structures causing a separation in the layers of concrete that produces an internal void. If not detected prematurely, delamination could lead to a loss of mechanical properties of the structure. The purpose of this thesis is to develop an automatic software for detecting delamination in concrete structures. For better understanding and increasing the knowledge on this field, an overview of the main non-destructive testing methods has been made. The impulse response test has been the one chosen for detecting delamination in this research. A delamination detecting method has been developed using the MATLAB software. In the experimental part, artificial delamination was simulated with 3D printed pieces placed inside the concrete slabs at different depths. The results from the experimental tests are represented with the mobility plot obtained with the impulse response method. Due to that it hasn’t been possible to detect delamination in the mobility plot, results are also given with the accelerance function, where delamination could have been detected in two different depths.