An instrument for detecting corrosion in anchorage zones of bridge cables using guided waves

Corrosion often occurs in anchorage zones of bridge cables which is a serious problem to the bridge safety. Moreover, accessing to an anchorage zone for corrosion detection is nearly impossible. An instrument for detecting corrosion in anchorage zones of bridge cables using guided waves is described. This instrument consists of a transmitter, a receiver, a power amplifier, a signal generator, a signal processing circuit, a power supply system and a software program. The instrument can detect corrosion in anchorage zones from the free length of cable and without removing the stainless steel sheath and the high density polyethylene coating. The corrosion (approximately 5% cross sectional area) in the anchorage zone of a parallel wire cable is detected using this instrument. The instrument has gained the favourable results in laboratory experiments and field applications since 2006.