Comprehensive Assessment of Polymeric Additives on the Rheological Durability and Aging Resistance of Modified Bitumen

Abstract

This study investigates the performance of bitumen modified with different polymer-based additives including styrene-butadiene-styrene (SBS), Enprene 611, Enprene 701, crumb rubber (CR), and Elvaloy + PPA. The base bitumen used in the study was B70/100 bitumen obtained from the Batman Refinery. Modified bitumens were produced at different additive contents and evaluated through conventional and rheological tests including penetration, softening point, rotational viscosity, dynamic shear rheometer (DSR), Multiple Stress Creep Recovery (MSCR), and bending beam rheometer (BBR) tests. The results showed that polymer modification significantly improved the high-temperature performance of the bitumen. Among the tested modifiers, the 4-611 bitumen exhibited the highest rutting resistance, increasing the G & lowast;/sin delta value up to 6.08 times higher than the base bitumen at 76 degrees C, while the 8CR bitumen demonstrated the lowest nonrecoverable creep compliance (Jnr) in the MSCR test, indicating superior resistance to permanent deformation. Penetration values decreased by up to 53.78% with 4% Enprene 611, while the softening point increased up to 1.32 times compared to the base bitumen. Viscosity values increased with increasing modifier content, confirming the stiffening effect of elastomeric additives. Phase angle results indicated enhanced elastic behavior for all modified bitumens, particularly for CR and 611-modified bitumens. In terms of performance grading, the base bitumen exhibited PG 70-22, whereas the modified bitumens achieved higher grades including PG 82-16, PG 82-22, and PG 88-22, demonstrating substantial improvement in rutting resistance. Overall, the findings indicate that polymer and rubber modifiers significantly enhance the rheological and mechanical performance of asphalt bitumens, with Enprene 611 and CR providing the most notable improvements in high-temperature rutting resistance and elastic recovery behavior.