This research investigates the rheological and micro-structural characteristics of warm bitumens and bituminous mastics containing a newly introduced chemical warm additive namely PAWMA® in comparison with Zycotherm® as a chemical additive and Sasobit® 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 micro-structural properties were examined by atomic force microscopy (AFM) procedure. Based on the results, despite reducing the mixing temperature for warm mastics, PAWMA® showed similar rheological and micro-structural properties to reference mastic. Sasobit® 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.