Monitoring of bitumen hardening with a non-destructive ultrasonic shear wave reflection technique

The article presents a possibility of using a non-destructive ultrasonic shear wave reflection technique for monitoring hardening process of bitumen. The technique relies on the use of a new measuring instrument called USWR-4 Hardening meter, which was developed to be applicable directly in situ and has been effectively used for cement-based materials so far. It works on the principle of continuous measurement of change of a shear wave reflection coefficient. Three different types of paving grade and two polymer-modified bitumens were used. Results show that the presented ultrasound technique can effectively track a temperature-dependent hardening process of bitumen.