Structural and Rheological Principles of Formation of Stable Bituminous Sealants with Polymer-Fiber Reinforcement

The development of durable road sealing materials capable of maintaining performance under combined mechanical and climatic loads remains a critical challenge for modern infrastructure. Conventional bitumen-based sealants exhibit limited resistance to high-temperature deformation, cracking, and adhesion degradation, leading to reduced service life. This study proposes a rheology-oriented approach to the design of polymer-reinforced bituminous sealants based on penetration-grade bitumen 50/70 and 70/100 modified with styrene–butadiene–styrene (SBS) copolymers up to 9 wt.% and reinforced with cellulose fibers. The rheological behavior of the developed composites was investigated using dynamic shear rheometry to determine the complex shear modulus (G*), phase angle (δ), and temperature–frequency dependencies in the range from −20 to +90 °C, while infrared spectroscopy was employed to assess intermolecular interactions. Adhesion performance was evaluated at different temperature. The modified systems demonstrated a 5–10-fold increase in G*/sinδ enhanced high-temperature stability, and improved adhesion and crack resistance compared to base bitumen. Based on the obtained rheological and performance indicators, the developed composition was approved for subsequent pilot-scale testing and field validation as a promising road sealing material.