Comparison of Ultrasonic Pulse Passage Velocity in High-Strength Concrete and Ordinary Concrete, Under High Temperature Based on XRD and SEM Analyses, for Use in Pavement

One of the disadvantages of using conventional concrete in road paving is its low resistance to traffic loads. But today, scientists have been able to improve the strength of concrete by using new materials such as slag in the composition of concrete. These materials contain adhesives and fillers such as aluminate and silicate, which ensure the improvement of strength in concrete after the process of chemical reaction with alkaline solutions. The purpose of this laboratory research is to make concrete with higher strength than ordinary concrete used in road pavement. In this regard, a mixing plan was made of ordinary concrete with a cement grade of 450 kg/m3. A mixing design was also made of fermented concrete based on composite kiln slag to compare and evaluate the ultrasonic pulse (UPV) rate of concrete under ambient temperature and temperature of 500 °C, at a 90-day curing age. Continuation of X-ray diffraction (XRD) spectroscopy and scanning electron microscopy (SEM) imaging tests to further evaluate and verify the UPV test results at 90 days of processing at ambient temperature and 500 °C on the sample Concrete works were carried out. Based on the results, the amount of UPV at ambient temperature was 5930 m/s for ordinary concrete and 4920 m/s for alkaline concrete, which had a difference of 17.03%. By applying heat to concrete samples, the rate of UPV drop in ordinary concrete was 37.26% and in quilted concrete was 45.93%. The results of XRD and SEM tests were in agreement with each other and overlapped with the results of UPV test.