MODIFICATION OF BITUMINOUS BINDERS FOR ASPHALT CONCRETE PAVEMENTS

Abstract

The review is devoted to the analysis of modern research in the development of formulations and technology for the manufacture of composites based on bituminous binders for the creation of improved asphalt concrete. Methods for modification of bitumen by polymer additives, chemical stabilizers, industrial wastes (recycled polymers, ground tire rubber, fly ash, etc.), nanodispersed additives and carbon nanomaterials to obtain the necessary predetermined properties are considered. The positive and negative aspects of using various modifiers are analyzed. The efficiency of modification of bituminous binders with recycled polymers and nano(ultra)dispersed fillers is shown, which makes it possible to create composites based on bituminous binders for asphalt concrete pavements with high performance characteristics. The optimal content of additives to the bitumen binder has been analyzed: the amount of thermoplastic polymers and thermoplastic elastomers in the range of 3-10 wt.%, thermosetting polymers − over 10 wt.%, elastomers − up to 15 wt.%, and nano-sized additives: nano-oxides ≥ 5 wt.%, nanoclay ~ 3 wt. %, carbon nanotubes, graphene < 1.2 wt.%. Modification of bitumen with recycled polymers and partial replacement of expensive polymer modifiers with cheaper polymer waste, composite modifiers, namely recycled polymer mixed with ground tire rubber and / or fly ash are considered. This allows solving the environmental problems (waste utilization and secondary use) and reduce the cost of asphalt concrete. From the analysis of the experimental results, it becomes clear that for prediction of the properties of modified asphalt concrete, the basic characteristics of the original bitumen, which can differ significantly, are important, as well as the type of modifier (combination of modifiers), its chemical nature, and the efficiency of its dispersing in bitumen. The different chemical composition of the initial bitumen and its physicochemical properties probably play a primary role in imparting high and low temperature properties to asphalt concrete. Modification of a bituminous binder with waste polymers and nanofillers, first of all, makes it possible to improve such important performance characteristics of bitumen and asphalt concrete, such as softening temperature, penetration, penetration index, ductility, viscosity, moisture resistance, complex shear modulus, rutting parameter, resistance to cracking, etc.