The American Concrete Institute (ACI) has released a paper called the Effect of Acoustoelasticity on Ultrasonic Pulses and Damage of Concrete under Tensile Stresses.
The document, written by Carnot L. Nogueira and Kevin L. Rens, used Longitudinal and transverse ultrasonic pulse velocities to assess acoustoelastic effect and damage in concrete under tensile stresses.
For the programme, six concrete mixtures were tested using third-point loading tests.
ACI says: “During stress application, longitudinal and transverse ultrasonic pulses were transmitted perpendicularly to the applied stresses; transverse pulses were polarized in the tensile stress field direction and normal to stress field, and Murnaghan acoustoelastic parameters were calculated.”
“After separating the acoustoelastic effect and obtaining net pulse velocities, two scalar damage models were used to evaluate degradation due to loading”, ACI adds.
One damage model assumed elastic modulus degradation, while the second model was based on shear and elastic moduli.
According to ACI: “The high magnitudes of the third-order Murnaghan parameters indicate the strong influence of the acoustoelastic effect in ultrasonic testing of concrete.”
These results also revealed that both moduli degrade at the same rate when concrete is under tensile stresses.
