Effects of Experimental Parameters in Monitoring the Hydration of Cement Mortars by Ultrasonic Testing

摘要

In ultrasonic pulse velocity testing, frequency and the travel path length are important parameters that determine the attenuation rate and the influence of near-field effect. Higher frequencies and longer distances result in higher attenuation. On the other hand, smaller path lengths are not desirable due to near-field effect. This study investigated the effect of transducer frequency and the length of path used to determine ultrasonic wave velocity in monitoring the hydration process of fresh cement mortars. For this purpose, an experimental set-up was prepared to observe the ultrasonic pulse velocity (UPV) development in cement mortars during the first 24 hours after mixing. Mortar mixtures with a water/cement ratio of 0.5 were tested for 15,10 and 5 cm travel path lengths at 54, 82 and 150 kHz frequencies. UPV curves were obtained in each test and some characteristic points on the curves were determined. The results showed that choosing the appropriate frequency and travel path distance is important in monitoring the UPV development in fresh cementitious materials.