건설재료시공학연구실

Building material & construction lab.

ABSTRACT
As the residual mechanical properties of concrete subjected to high-temperature heating deteriorate because of continuous degradation, it is necessary to evaluate the integrity of the concrete in real time. Hence, the applicability of degradation monitoring (continuous integrity evaluation) for concrete subjected to high-temperature heating was examined by employing ultrasonic pulse velocity. In this study, the mechanical properties and ultrasonic pulse velocity of concrete subjected to high-temperature heating were evaluated for ordinary-strength to ultra-high-strength concrete. To measure the ultrasonic pulse velocity in concrete during high-temperature heating, transducers were connected to the upper and lower surfaces of the concrete specimens and pressed using SUS bars. The contact surface was cooled using cooling devices. Consequently, the ultrasonic pulse velocity in concrete subjected to hightemperature heating remained constant up to 300 °C; however, it tended to decrease in the higher temperature range. Furthermore, as cracks and pores generated and expanded inside the concrete, the residual mechanical properties of the concrete rapidly declined. This decline at temperatures over 300 °C coincided with the reduction in the ultrasonic pulse velocity. Thus, it was confirmed that the ultrasonic pulse velocity could be applied to monitor the integrity of concrete.