Ultrasonic Waves Attenuation In Various Concrete
Sabah S. Abdulnoor, B.Sr., M. Sc., ph. D., University of technology. Moufaq J. Katwan, B.Sc., ph. D., Director General of NCCL, Baghdad ,Iraqi
Yasir K. AL-Ani, B. Sc., M. Sc., University of Baghdad. Received 26/10/1999 Accepted 6/5/2000
Various concrete composites were prepared by reinforcing plain concrete with crimped steel fibers (0.5% and 1 %) volume fraction, and fibrillated polypropylene fibers (0.5%. 1%, 1.5% and 2%) volume fractions separately.
The attenuation behaviour of Ultrasonic waves travelling in individual composites was investigated. Attenuation coefficients (a) of various composites were determined at different frequencies using pulse velocity method. The decline of Ultrasonic wave amplitudes was also investigated. Moreover, values of longitudinal (compressive) and transverse (shear) velocities of the ultrasonic waves travelling through the composite bulk, were also determined.
The quality factor (Q) of the various composites was determined by measuring the band width of resonance curve using the resonant frequency test. The (Q) values was found to decline with increasing presence of reinforcing fibers, suggesting an increased dissipation of the incoming wave energy within the bulk. Thus reducing the effect of the stored energies that may result in a plastic deformation and thus failure. This is in agreement with the observed enhancement of attenuation coefficient (α) with increased volume fraction of reinforcing fibers, and the decline of the amplitude of the travelling waves.