eva‎luation of the effect of two polymers of cellulose nanowhisker and polyvinyl alcohol on the mechanical properties of asphalt mixtures

1/11/2023 12:00:00 AM

The rheological properties of asphalt binder used in the manufacture of asphalt mixtures significantly affect their durability and performance and play an essential role in the occurrence of defects such as rutting, cracking, and moisture susceptibility. Modifying binders with special additives is one of the practical solutions to prevent premature failures and improve the mechanical properties of asphalt mixtures. Recently, binder modification with organic polymers has been considered by many asphalt industry researchers. This study has eva‎luated the mechanical and durability properties of modified asphalt mixtures with two different types of polymers with different percentages, including 1.5, 2.5, and 3.5% of polyvinyl alcohol polymer (PVA) and 1, 3, 5, and 7% of Cellulose Nano Whiskers polymer (CNWs). For this purpose, various mechanical tests such as dynamic creep at 54.4 ° C, resilience modulus test at 25 ° C, Marshall stability test, indirect tensile test, and semi-circular bending (SCB) test at -15 ° C were used. Also, the effect of different percentages of using two polymers on the modified binder's viscosity was eva‎luated using the rotational viscosity test. The results of the rotational viscosity test showed that the use of polymer additives increases the viscosity of the base bitumen and the amount of mixing and compaction temperature. Also, a comparison of mechanical performance and durability of modified asphalt mixtures showed that with increasing the percentage of both polymers, Marshall stability, flow number, resilient modulus, and resistance to moisture susceptibility had increased significantly. The cows and PVA had the most significant effect on increasing the resistance to rutting and moisture susceptibility, respectively. The results of the SCB test at -15 °C also showed that with increasing the percentage of PVA use, the amount of fracture toughness, critical load, and fracture energy of modified asphalt mixtures increased. Conversely, for CNWs, by increasing the percentage of use of this polymer up to 5%, the values of fracture toughness, critical load, and fracture energy of asphalt mixtures have increased. With increasing percentages, the values of these parameters have decreased by 7%.

Hossein Valadi

Dr. Hassan Ziyari