LDPE/GTR/elastomer ternary blends with variable LDPE/GTR ratio and constant elastomer content were prepared via melt-compounding. Obtained LDPE/GTR/elastomer blends were applied as thermoplastic modifiers into bitumen. Microstructure, physical and thermal properties of the modified bitumen were determined. It was observed that chemical composition of LDPE/GTR/elastomer blends has significant influence on their density and rheological behavior, which are also main factors affecting the dispersion of LDPE/GTR/elastomer blends into bitumen matrix and interfacial interactions between used components. Microstructure and thermal behavior of modified bitumen confirmed that physical interactions between bitumen and LDPE/GTR/elastomer blends are limited with increasing content of GTR. This phenomenon is due to mainly cross-linked structure of GTR and its low flowability. The conducted investigations showed that interfacial interactions between of thermoplastic modifier and bitumen, therefore the conventional and thermal properties of modified bitumen can be improved and easily modified by changing composition of LDPE/GTR/elastomer blends