Evaluation of Fatigue Damage of Concrete using Impact Echo Method

The impact echo technique is traditionally used to determine position of defects within
concrete structures. Impact echo technique is non-destructive, non-intrusive, and cost
and time efficient. In this paper, application of impact echo in assessing crack
development n concrete structures subjected to cyclic load is discussed. Research work
is carried out by performing impact echo test on concrete plain beam 150mm x 150mm
x 750mm subjected to cyclic load. Mechanical stress wave is generated by striking the
concrete surface with 7mm diameter steel ball. The reflected stress wave is then
detected by accelerometer and displayed result in the form of amplitude-frequency
waveform on the screen of an oscilloscope. The waveform recorded at certain interval of
cyclic loading is analysed to estimate the crack development in concrete. It is found that
impact echo result has a strong correlation with the concrete fatigue life. There is also a
great potential of using Impact echo method to predict the remaining service life of a
concrete structure subjected to cyclic load. However many parameters can affect the
accuracy of impact echo result, more research need to be done and many conditions
need to be taken into consideration when implementing this method in predicting the
remaining service life of concrete structure.