Influence of Processing Temperature on the Modification Route and Rheological Properties of Thiourea Dioxide-Modified Bitumen

Abstract

This work deals with the effect that processing temperature exerts on the modification of bitumen by thiourea dioxide (ThD). In that sense, shear and bending rheological tests, (thermal analysis thermogravimetric analysis/derivative thermogravimetric analysis/differential thermal analysis (TG/DTG/DTA) and modulated differential scanning calorimetry (MDSC)), and chemical characterization by thin layer chromatography coupled with a flame ionization detector (TLC-FID) were carried out on neat bitumen with a penetration grade (pen.) of 40/50 and corresponding 9 wt % ThD modified samples, prepared at 90, 130, and 180 °C. Tests carried out on those binders revealed the existence of a different modification mechanism at every temperature. In any case, viscosity was always seen to increase after ThD addition. Also, modification enhanced elastic properties and thermal susceptibility at high in-service temperatures and yielded improved binder resistance to thermal cracking by a decrease in its glass transition temperature. These results suggest that the use of thiourea dioxide may become a promising alternative to the use of other chemical modifiers for the paving industry.