Influence of polymer additives on the rheological properties of bitumens.

It is important to incorporate polymers into bituminous binders to improve the quality and performance of asphalt. Currently, polymer-modified asphalt binders (PMBs) play an important role in road engineering. Polymer modifiers absorb the maltene fractions of bitumen and form a three-dimensional network within the binder. The service life of polymer-modified asphalt pavements is approximately 24% longer than that of conventional pavements. Polymer additives are used to improve the properties of bitumen, such as increasing its strength and resistance to loads and extreme temperatures. Common additives include elastomers such as styrene-butadiene-styrene (SBS) and styrene-butadiene rubber (SBR). Plastomers such as ethylene vinyl acetate (EVA) are also widely used. These additives improve the stiffness and high-temperature performance. These modifications create polymer-modified bitumen, which is used in road surfaces to prevent cracking, rutting, and other types of wear, especially in areas with heavy traffic or extreme climates. Some of the main types of polymer additives include SBS, a common elastomer that improves elasticity and flexibility, making asphalt more resistant to cracking and rutting, especially at high temperatures and under heavy loads, and EVA, a plastomer that gives bitumen stiffness and strength. Styrene-butadiene rubber (SBR) is another elastomer used to modify bitumen and exhibits properties similar to SBS. Crumb rubber is a recycled material obtained from waste tires and can be used as an alternative modifier. Other additives include ethylene-propylene copolymers and various polyalkyl methacrylates, although the latter materials sometimes have limited applicability. The advantages of polymer modification include increased durability (makes the asphalt pavement more resistant to wear), increased thermal stability (improves performance at both high temperatures (rutting) and low temperatures (cracking)), increased elasticity and recovery (improves flexibility, allowing the pavement to better withstand loads), and reduced maintenance requirements (extends the service life of the pavement). This paper provides a review of research studies on the use of polymer additives to improve the rheological properties of bitumen. Although numerous studies have investigated individual polymer modifiers to date, there is still no comprehensive comparative review examining the effects of different polymer classes on the rheological behavior, compatibility, and long-term performance of bitumen. Therefore, this review aims to provide a systematic and comparative evaluation of polymer additives used in bitumen modification.