Sensitivity Assessment of the Nonlinear Resonant Ultrasonic Spectroscopy for Concrete Damage Detection

Nonlinear Resonant Ultrasound Spectroscopy is a nondestructive acoustic method which is able to measure the bulk hysteretic nonlinearity. This method monitors the shift of the resonant frequency in response of variations in the excitation frequency amplitudes. Measurements were performed on concrete samples exposed to temperatures of 200, 400, 600, 800, 1000, 1200 °C. The elastic modulus values are given to compare the Nonlinear Resonant Ultrasound Spectroscopy (NRUS) sensitivity. These are calculated from the measured velocities of ultrasonic pulses (linear acoustic method) and from the bulk density. The strengths of the samples obtained by destructive methods are also given. Based on these results, the NRUS method can be described as a very sensitive indicator of damage in concrete.