Evaluation of Mechanical Properties of Activated Alkali Concrete Based on Non-Destructive Ultrasonic Wave Velocity Testing

Abstract

In this experimental study, a mixed design of ordinary concrete containing Portland cement (OPCC) with a grade of 500 kg/m³ and a design of activated alkali concrete (AAC) based on granulated blast furnace slag (GBFS) were made. In order to investigate the mechanical properties, ultrasonic pulse velocity (UPV) tests were performed on concrete designs at a temperature of 21 ℃ at curing ages of 7, 28 and 90 days. The results indicated that the UPV improved with increasing curing age in OPCC and AAC samples. In this regard, in OPCC, the minimum (4128 m/s) and maximum (6179 m/s) UPV was obtained at curing ages of 7 and 90 days, respectively, which had a superiority of 49.68% at the age of 90 days. In AAC, the minimum (4723 m/s) and maximum (5531 m/s) UPV was achieved at 7 and 90 days of curing, respectively, with a 17.1% advantage at 90 days. At 90 days of curing (as the optimum age), the UPV in AAC decreased by 11.71% compared to OPCC at the same age. The results of the analysis of scanning electron microscope (SEM) images on concrete samples in this study were in complete agreement with the UPV test results.