Impact-echo thickness frequency profiles for detection of voids in tendon ducts

摘要

The detection of voids in grouted tendon ducts in concrete structures is of key importance to the civil engineer. The methods commonly used or such detection is gamma-or x-ray radiography. Unfortu- nately, these powerful technique have the disadvantage of requir- ing a large security zone for radiation protection. Since the end of the 1980s, the impact-echo method, among Other nondestructive testing methods, has also been proposed. Shifts in the frequencies associated with the duct depth and in the Frequency associated with the slab thickness have been used as Indicators of voids inducts.