PI8000

In all cases you need to calibrate the wave velocity. If you do not know the expected length, you can always play with an approximate wave velocity of 3.500m/s to 4.500m/s.

For these types of cases, you will use an...

In all cases you need to calibrate the wave velocity. If you do not know the expected length, you can always play with an approximate wave velocity of 3.500m/s to 4.500m/s.

For these types of cases, you will use an approximate value of the wave velocity. It will be easy to find defects by using the comparison mode and comparing the graphics of different piles. However, the location of the defect, and the total length of the pile, will be always an approximate value of the reality.

On the other side, the wave velocity can be calibrated using other apparatus, like pundit 200 using cross section wave velocity measurement.

The maximum thickness that can be tested using Impact Echo depends on many factors, but it is normally related to the quality of the concrete and the selected impactor.

Normally, the backwall is clearly visible in...

The maximum thickness that can be tested using Impact Echo depends on many factors, but it is normally related to the quality of the concrete and the selected impactor.

Normally, the backwall is clearly visible in structures up to 60cm, but in some cases, we can extend this value up to 80cm. Note that Impact Echo is meant for plate-like structures (minimum length > 6 * thickness): walls, slabs, etc. And it does not always provide readable results for slender elements such as columns or beams. 

That depends on the size of the element to be tested. The bigger the impactor, the lower the frequency it creates. Low frequency waves are able to travel further, however its resolution is poorer so they are not as good as...

That depends on the size of the element to be tested. The bigger the impactor, the lower the frequency it creates. Low frequency waves are able to travel further, however its resolution is poorer so they are not as good as to identify small defects. On the other side, the smaller the impactor, the bigger the frequency it creates. High frequency waves do not travel deep, but they have much better resolution, which is useful for detecting small defects. 

If you want to find the backwall of a thick element, you should use the red hammer. If you want to identify small defects in superficial areas, you should use the blue impactor.

Recalibration of the apparatus is not required. ASTM does not specify a period for PIT or IE recalibration. Sensor calibrations are no relevant unless both force and acceleration are measured, which is not the case.

Only...

Recalibration of the apparatus is not required. ASTM does not specify a period for PIT or IE recalibration. Sensor calibrations are no relevant unless both force and acceleration are measured, which is not the case.

Only calibration of the wave velocity is needed each time you start inspection a new structure.

Do as many impacts as possible per spot.

Try to be careful while testing: cleaning the surface is really important, coupling the signal is a key aspect, applying constant pressure on the sensor, applying constant force on...

Do as many impacts as possible per spot.

Try to be careful while testing: cleaning the surface is really important, coupling the signal is a key aspect, applying constant pressure on the sensor, applying constant force on the hammer, vertically aligning the sensor on the concrete surface, etc.

Then try to calibrate the wave velocity and revise if you are getting good signal. If that is not the case, find another alternative spot in the same pile / wall and repeat the testing until you receive good signal.

If you have a clear signal, data processing will be really easy as you can always use the high and low pass filters to eliminate the signal noise, and also the time gain compensation to increase the signal amplitude.