Understanding Acoustic Emission Testing- Reading 1 Part B-A

16.6.3 Signal Attenuation
The elastic stress waves that are generated by cracking attenuate as they
propagate through the concrete. Thus, large acoustic emission events that
take place in the concrete far from a pick-up transducer may not exceed the
threshold excitation voltage due to this attenuation, while much smaller
events may be recorded if they occur close to the transducer. Very little
information is available on acoustic emission attenuation rates in concrete. It
has been shown that more mature cements show an increasing capacity to
transmit acoustic emissions. Related to this, Mindess has suggested that the
total counts to failure for concrete specimens in compression are much higher
for older specimens, which may also be explained by the better transmission
through older concretes.
Charlie Chong/ Fion Zhang