Rheological and micro-structural properties of bituminous mastics containing chemical and wax warm additives

摘要

This research investigates the rheological and micro-structural characteristics of warm bitumens and bituminous mastics containing a newly introduced chemical warm additive namely PAWMA (R) in comparison with Zycotherm (R) as a chemical additive and Sasobit (R) as a conventional wax additive. A 60/70 penetration grade bitumen was used as the reference binder in producing bitumen and mastic specimens. In preparing mastics, limestone powder was added to the base bitumen as much as 60% by weight of bitumen. Three warm additive contents including 1, 3 and 5% for Sasobit, 0.2, 0.4, and 0.6% for PAWMA and 0.07, 0.10 and 0.15% for Zycotherm were added to mastics, by weight of bitumen. Dynamic shear rheometer was perfromed on bitumens and mastics after short and long-term aging processes. Also, the microstructural properties were examined by atomic force microscopy (AFM) procedure. Based on the results, despite reducing the mixing temperature for warm mastics, PAWMA (R) showed similar rheological and micro-structural properties to reference mastic. Sasobit (R) evidently changed the micro-structural properties in terms of topography roughness and the catana-phase structure while the use of different chemical additives percentages had no significant effects on nano-scale structure and AFM topography in comparison with reference mastic. (C) 2020 Elsevier Ltd. All rights reserved.