Abstract
A new ultrasonic coupling powder has been developed where the gel of conventional contact mediums is replaced with powder. In this method, ultrasonic testing is carried out while compressing the powder between probes and concrete surfaces by applying pressure to the probes. Even though the powder usually prevents the transmission of elastic waves, they can be transmitted through it under pressurized conditions. In addition, the acoustic impedance can be matched to that of mortar or concrete by controlling the pressure applied to the powder. In this paper, this ultrasonic coupling powder was applied to the testing of mortar test specimens. The results were that the amplitudes of the back reflection increase as the pressure of the powder increases. These results were compared to those from grease coupling. The problem with the coupling powder is the necessity of high pressure applied to the powder. Our solutions to this problem are outlined in the last section.
