An Ultrasonic Pulse Velocity Test on Fly-Ash Based Geopolymer Concrete in Frequency Domains

Abstract

The Non-Destructive Test techniques on concrete, which can assess the properties of materials without damages, have been developed as the deteriorations of existing structures increase. Among them, the ultrasonic pulse velocity (USPV) method is widely used because it can investigate the states of one material for a long time and repeatedly. However, there have been few researches on the NDT application to geopolymer concrete which is environment friendly construction material without any cement. This paper investigates the variations of ultrasonic pulse velocity and peak frequency of geopolymer concrete under monotonically increasing loads to assess the material conditions with various compressive strength levels by measuring P-wave signals. The pulse velocities and peak frequencies were higher in high strength geopolymer concrete specimens. There are not explicit relations between strength levels and peak frequencies but the peak frequencies are strongly influenced by the applied stress levels. In addition, a predicting equation for compressive strength of geopolymer concrete is derived based on experimental data in similar form for normal concrete.