Chasing the Bubble: Ultrasonic Dispersion and Attenuation from Cement with Superabsorbent Polymers to Shampoo

Abstract

This study aims to experimentally investigate the ultrasonic behavior of fresh cement focusing on the contribution of the entrapped air bubbles. Frequency dispersion and attenuation carry delicate information that is not possible to gather by traditional ultrasonic pulse velocity. This is measured by simple indicators that quantify the frequency dependence of propagation velocity of longitudinal waves through fresh cementitious media. It seems that dispersion shows much stronger sensitivity to the microstructural processes, since the presence of superabsorbent polymers in mortar induces a large difference in dispersion parameters when compared to reference cement mortar, while only marginal difference in threshold-based pulse velocity. To reach this aim, references are taken from, and comparisons are made to other liquids in order first in order to validate the reliability of the methodology and to better understand the contribution of the cavities in the obtained dispersion and attenuation curves. Ultrasonic dispersion assessment of cementitious media has the potential to bring a lot of information on the microstructure of materials, as well as the ongoing processes.

Monitoring Of Fresh Concrete With Superabsorbent Polymers (Saps) Using Acoustic Emission (AE)

“…This makes the localization in the highly attenuative nature of cementitious materials complicated. To overcome this issue, different velocities were used to account for each curing stage and changing stiffness, based on ultrasonic measurements conducted by Lefever et al [7] on mortar specimens made using the same cement as this study. Although the velocity of mortar is not the same as the one of concrete, a good approximation can be derived from the results of [7].…”

“…To overcome this issue, different velocities were used to account for each curing stage and changing stiffness, based on ultrasonic measurements conducted by Lefever et al [7] on mortar specimens made using the same cement as this study. Although the velocity of mortar is not the same as the one of concrete, a good approximation can be derived from the results of [7]. Early UPV measurements on concrete specimens unfortunately are not possible due to the highly attenuative nature of the material, but also due to the larger required mold thickness compared to mortar.…”

Sensor Size Effect on Rayleigh Wave Velocity on Cementitious Surfaces

“…The difference of the two phases in combination with the sensor separation distance leads to the phase velocity for each frequency component. More details on the calculation are supplied in [ 40 ]. To avoid contamination of the results from components other than Rayleigh (reverberations and initial longitudinal arrivals) the signal was processed by zero-padding the rest of the waveform after maintaining the strong Rayleigh cycles, as is common in similar cases [ 4 , 41 ].…”