A preliminary study on ultrasonic non-destructive testing of concrete in maritime environment

This paper describes an experimental study in which non-destructive testing (NDT) of concrete in marine and a non-marine environment was performed. Nine (150mm x 150mm x 150mm) cubic specimens from three batches of concrete with w/c of 0.40, 0.50, and 0.60 and with appropriate variations in cement and sand were prepared. The hardened concrete specimens were cured under controlled laboratory conditions for 28 days. In the first stage the cubic specimens were tested using through-transmission NDT technique lying simply on laboratory floor, representing a typical of non-marine environment. Afterwards, for simulating marine-like environment, the cubic specimens were retested lying in a water tank. The underwater through-transmission of the specimens was performed. The results obtained from both ways of testing were recorded and plotted in time and frequency domains. P-wave velocities and attenuation of the wave signals were measured and compared. Additionally, the wave reflection factor (WRF) was calculated and compared for specimens tested under water. The results show that the wave attenuation, the P-wave velocities in concrete, and the WRF are highly influenced by the w/c ratio. The outcomes of this study can be useful in conducting research on testing actual maritime concrete structures