Homogeneity Evaluation of Fiber-Reinforced Concrete Using Diffuse Ultrasound

초록

This study aims to evaluate the homogeneity of concrete using the diffuse ultrasound theory. Ultrasound propagating within concreteundergoes diffusion and dissipation due to changes in the microstructure, which can be approximated as scattered wavelengths using thediffuse ultrasound theory. Therefore, analyzing the diffusion and dissipation processes of ultrasound enables the detection of changes ininternal homogeneity. In this study, fiber inclusion was introduced as a factor influencing changes in the concrete microstructure. To evaluatethe versatility of the homogeneity analysis method, experiments were conducted using commonly used reinforcement fibers: CARBON, JUTE,GLASS, and STEEL. Additionally, fiber content was categorized into 0.5% and 1% to analyze its effect on homogeneity changes. Theexperimental results showed that the diffusion coefficient was highest in the concrete specimen without fiber reinforcement (NC), and in mostfiber-reinforced specimens, an increase in fiber content led to a decrease in the diffusion coefficient. This phenomenon is attributed to theincreased ultrasonic scattering caused by decreased internal homogeneity, resulting in delayed diffusion. In the case of dissipation, mostfiber-reinforced specimens exhibited lower dissipation coefficients than the NC specimen, except for specific mixtures. However, no clearcorrelation was observed between fiber content and changes in the dissipation coefficient. This result suggests that dissipation is significantlyinfluenced by the size and shape of internal inhomogeneities.

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