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INVESTIGATION OF THE PERFORMANCE OF BITUMEN AND BITUMINOUS MIXTURES MODIFIED WITH GRAPHENE AND HEMP OIL

Purpose: The aim is to develop advanced modified bitumen and bituminous mixtures by incorporating graphene and hemp oil into bitumen to create next-generation asphalt binders. By optimizing the amount of additives, the objective is to prevent unnecessary or excessive use and design bituminous hot mixtures that enhance performance and reduce crack formation. Method: Using the Taguchi optimization method, an experimental plan consisting of 4 parameters with 4 levels was prepared. In accordance with this plan, the physical, chemical, and mechanical properties of bitumen and bituminous mixtures produced with 16 different combinations were examined. Findings: The average values of the elastic recovery ranged from 5% to 12.50%. The average mass loss values from the RTFOT mass loss test ranged from 27.02‱ to 57.48‱. While the softening point of pure bitumen was 45.50°C, the average values from the tests ranged from 43.90°C to 48.40°C. The penetration value of pure bitumen was 90.8, while the average penetration values from the tests ranged from 79.03 to 140.07. Marshall stability values ranged from 911 kg to 1178 kg. In the SCB tests, fracture toughness values ranged from 16.75 to 29.45 MPa√m. In the SENB tests, fracture toughness values ranged from 22.34 to 31.33 MPa√m. Results: As a result of MRPI optimization, the optimum parameter levels were found to be "A2, B2, C4, D2." In MRPI optimization, the most significant contributions were from graphene nanoplatelets at 42.43% and hemp seed oil at 28.75%. In the confirmation tests based on the MRPI optimum parameter levels, the results showed an increase of 14.4% in penetration, 27.33% in penetration after RTFOT, 4.62% in softening point, 4.53% in softening point after RTFOT, 4.83% in stability, 3.43% in SENB fracture toughness at -20°C, 18.03% in SCB fracture toughness at 0°C, and 50.84% in SCB fracture toughness at -20°C. Keywords: GNP, Hemp Seed Oil, SCB, SENB, Marshall, Taguchi Method