Elastic properties of fly ash-stabilized mixes
Stabilized mixes are used in the construction of bearing layers in asphalt and concrete pavement structures. Two nondestructive methods: resonant frequency method and ultrasonic pulse velocity method, were used for estimation of elastic properties of fly ash–stabilized mixes. Stabilized mixes were designed containing sand from the river Drava and binder composed of different share of cement and fly ash. The aim of the research was to analyze the relationship between the dynamic modulus of elasticity determined by different nondestructive methods. Data showed that average value of elasticity modulus obtained by the ultrasound velocity method is lower than the values of elasticity modulus obtained by resonant frequency method. For further analysis and enhanced discussion of elastic properties of fly ash stabilized mixes, see Dimter et al. [1].
Estimation of elastic properties of fly ash–stabilized mixes using nondestructive evaluation methods
This paper presents an estimation of elastic properties of fly ash–stabilized mixes using two nondestructive methods: resonant frequency method and ultrasonic pulse velocity method. The aim of the research was to determine the impact of changes in the composition of the mixes and in the regime of curing on the dynamic elasticity modulus. An additional goal was to analyze the relationship between the dynamic modulus of elasticity determined by different nondestructive methods. Results showed that average value of elasticity modulus obtained by the ultrasound velocity method is lower than the values of elasticity modulus obtained by resonant frequency method.
Theoretical and experimental analysis of longitudinal wave propagation in cylindrical viscoelastic rods
Wave propagation in viscoelastic rods is encountered in many applications including studies of impact and fracture under high strain rates and characterization of the dynamic behavior of viscoelastic materials. For viscoelastic materials, both material and geometric dispersion are possible when the diameter of the rod is of the same order as the wavelength. In this work, we simplify the Pochhammer frequency equation for low and intermediate loss viscoelastic materials and formulate corrections for geometric dispersion for both the phase velocity and attenuation. The formulation is then experimentally veri7ed with measurements of the phase velocity and attenuation in commercial polymethylmethacrylate rods that are 12 and 6:4 mm in diameter. Without correcting for geometric dispersion, the usable frequency range for determining the phase velocity and attenuation for the 12 mm rod is about 20 kHz, and about 35 kHz for the 6: 4mm rod. Using the correction procedure developed here, it was possible to accurately determine the phase velocity and attenuation up to frequencies exceeding 55 kHz for the 12 mm rod and 65 kHz for the 6:4 mm rod. These corrections are applicable to many polymers and other viscoelastic materials. From thereon, the viscoelastic properties of the material can be determined over a wide range of frequencies. ? 2003 Elsevier Science Ltd. All rights reserved.