Rheological and Performance Properties of a Bituminous Binder Modified with Date Kernel Powder

This study presents an experimental investigation into the direct use of date kernel powder (DKP) as a biomass-based modifier for bituminous binders, with the aim of evaluating its feasibility as a sustainable binder modifier. DKP was incorporated into a conventional bituminous binder at different contents (5, 10, 15, and 20 wt.% by weight of binder), and its physicochemical properties were characterized using SEM, XRD, and FTIR. The rheological and performance properties of the modified binders were evaluated through conventional tests, aging procedures, rotational viscosity (RV), dynamic shear rheometer (DSR), bending beam rheometer (BBR), and linear amplitude sweep (LAS) testing, and the performance grades (PG) of all binders were determined. The results indicate that DKP addition increases binder stiffness and reduces temperature susceptibility while maintaining acceptable fatigue and low-temperature performance. Performance grading results showed that the high-temperature grade increased from PG 64 to PG 70 and the low-temperature grade improved from PG-22 to PG-34 at a DKP content of 15%. LAS test results indicated that fatigue life was maintained or improved at intermediate temperatures. Among the tested contents, 15% DKP provided the most balanced performance considering performance grade improvement, fatigue behavior, and workability characteristics, while higher contents resulted in increased stiffness. Overall, the findings suggest that DKP is a promising modifier for bituminous binders at the binder level. However, further studies at the mixture and field scale are recommended to confirm the long-term engineering applicability of DKP-modified binders.