Identifying voids in plastic ducts in post-tensioning prestressed concrete members by resonant frequency of impact-echo, SIBIE and tomography

摘要

A series of standard concrete beams with plastic P-T tendon ducts were tested at the University of Edinburgh using a range of NDT techniques including impact-echo (I-E), stack imaging of spectral amplitudes based on the impact-echo (SIBIE) and ultrasonic tomography. The findings were confirmed by comparison with earlier experiments undertaken using GPR. It has been argued that I-E cannot detect voids in plastic post-tensioned ducts readily. However it has been shown that whilst I-E is less effective on plastic ducts, the SIBIE analysis is more certain. This technique is easier to use than ultrasonic tomography and gives a credible evaluation. The paper goes on to analyse the above tests on a number of beams with confirmation for ultrasonic tomography and GPR.