عنوان مقاله [English]
In this laboratory study, a mixing design was made of ordinary concrete containing Portland cement with a grade of 500 kg/m3 and a mixing design was made of alkaline concrete based on slag from the composing furnace. In order to investigate the mechanical properties, a non-destructive test was performed to determine the velocity of ultrasonic vibrations in concrete at 21 and 600 °C at a 90-day curing age. In order to evaluate the microstructure of concrete and verify the results of ultrasonic test, compressive strength test and scanning electron microscopy imaging was performed on concrete samples. The results showed a decrease in the speed of ultrasonic vibrations after applying high temperature (600 °C) in concrete, so that in ordinary concrete and hard concrete, the deceleration rate was 44.79% and 40.58% in the results after and before, respectively. Obtained by applying heat. In this regard, the passage speed of ultrasonic vibrations in ferrous concrete was lower than ordinary concrete, so that at 21 and 600°C, the percentage of velocity drop in ferrous concrete compared to conventional concrete is equal to 10.48 and 3.66%, respectively. Was obtained. The results of the compressive strength test and the images obtained from the scanning electron microscope, in coordination and overlap with the results of the ultrasonic vibration test in concrete were subjected to 21 and 600°C.