Effect of acoustic vibration frequency of concrete during hydration on mechanical properties

While extensive research has focused on the sound absorption properties of concrete, the effect of external acoustic vibration loads on its hydration process, mechanical performance, and microstructure remains
a significant scientific gap. This study investigates the influence of applying acoustic vibrations at varying frequency ranges during the critical hydration period. A conventional concrete mixture was subjected
to acoustic vibrations across five frequency ranges for 24 h during hydration, using a setup with two loudspeakers at constant sound intensity. A control sample was cured without any vibrations. The mechanical performance was evaluated through compressive and tensile strength tests at 7, 14, and 28 days
Microstructural analysis was conducted using scanning electron microscopy on selected samples.
The results demonstrated a clear negative impact on mechanical properties. The control sample achieved the highest compressive (37.2 MPa) and tensile (3.6 MPa) strengths at 28 days. The application of acoustic vibrations generally reduced strength, with the reduction being more severe at higher frequencies.
The sample E (10⁴-2·10⁴ Hz) showed the most significant decline, with compressive and tensile strengths 42.4% and 22.2% lower than the control, respectively. However, the effect was found to be frequency-dependent. Sample C (10³-5·10³ Hz) exhibited a relatively smaller reduction in strength compared to other treated samples, suggesting a less detrimental impact within this specific range. The study concludes that external acoustic vibrations during hydration disrupt the microstructure formation, leading to a decrease in the mechanical strength of concrete. No beneficial effects were observed within the tested parameters.