Spectral analysis of ultrasonic signals backscartted by mortar: Effect of sand size and temperatures

Abstract

This paper presents results of application of Ultrasonic Waves UW in civil engineering. The measurement has been performed by ultrasonic reflection technique using a transducer with central frequency 0,5MHz. Several methods of analysis and signal processing have been applied to detect the position of reflections and to measure the time of flight between two echoes related to the reflection at the mortar interfaces. The experiments performed in the laboratory are carried to determine the ultrasonic velocity of the wave backscattered by samples. This allowed determining the ultrasonic velocity of UW in the mortar in order to deduce the durability of each mortar according to its microstructure. The objective is to make a comparative study of the various methods of analysis of the ultrasonic signals as: Continuous Wavelet Transform (CWT), Wigner Ville (WVD), Pseudo Wigner–Ville distribution (PWVD), Smoothed Pseudo Wigner–Ville Distribution (SPWVD) and Hilbert Transform (HT).