Abstract
Rice straw is one of the most abundant agricultural residues worldwide, and open-field burning for its disposal causes a major environmental challenge. This study examined whether rice straw fiber (RSF), in both raw and chemically treated forms, can serve as a suitable modifier for asphalt binder and how that modification affects long-term pavement performance. Three Superpave base binders, PG 64-22, PG 70-22, and PG 76-22, were modified with untreated RSF at dosages of 2%, 4%, 6%, 8%, and 10% by weight of binder, while chemically treated fiber (2% NaOH) was incorporated into the PG 64-22 binder to isolate the effect of treatment on the conventional unmodified grade. All samples were evaluated in unaged, RTFO-aged, and PAV-aged states using the Dynamic Shear Rheometer, Multiple Stress Creep Recovery test, and Bending Beam Rheometer, while Fourier Transform Infrared Spectroscopy was used to analyze fiber-binder interactions. The rheological results showed that RSF raised the high-temperature rutting parameter with increasing dosage and increased the high-temperature PG compliance by approximately one performance-grade interval across all three binders, with treated fiber outperforming untreated fiber in the PG 64-22 binder. These gains, however, came with higher intermediate-temperature stiffness and reduced low-temperature relaxation capacity, marking a clear performance trade-off. FTIR indicated that the fiber interacted with the binder physically rather than chemically. To link these laboratory measurements to field behavior, machine learning models were developed from the LTPP SPS-10 database to predict rutting, fatigue cracking, transverse cracking, and the International Roughness Index, with the best models achieving R² values between 0.93 and 0.96. In the machine-learning scenario implementation, RSF reduced predicted rutting and roughness but increased predicted fatigue and transverse cracking, while the 3D-Move simulations predicted reduced rutting and reduced cracking under their mechanistic assumptions. The two methods are complementary scenario-based projections, not field validation, reflecting in part that the 3D-Move analysis varied only the binder-level inputs while holding the mixture-level modulus constant, since RSF-modified mixture data were outside the scope of this binder-focused study and they differed on cracking: the machine learning models projected slightly more fatigue and transverse cracking with higher dosage, while the 3D-Move analysis projected less top-down and bottom-up cracking. This divergence reflects differences in response variables, model assumptions, and the domains represented by each framework. Because RSF field sections were not available, the machine learning implementation should be interpreted as a scenario-based projection using LTPP-trained models rather than direct field validation. The results indicate that RSF improves rutting resistance and ride-quality indicators, but excessive dosage increases intermediate- and low-temperature cracking susceptibility; therefore, a balanced dosage range of approximately 4–6% is recommended. On this basis, RSF is identified as a promising, low-cost, and environmentally favorable binder modifier at the binder scale and within the modeled scenarios.
Date of publication
2026
Document Type
Thesis
Language
english
Persistent identifier
http://hdl.handle.net/10950/5116
Committee members
Dr. Mayzan Isied, Dr. Mena Souliman, Dr. Mrittika Hasan Rodela
Degree
Master of Science in Civil Engineering
Recommended Citation
Sigdel, Kriti, "MECHANICAL, MECHANISTIC, AND PERFORMANCE ASSESSMENT OF UNTREATED AND CHEMICALLY TREATED RICE STRAW FIBER-MODIFIED ASPHALT BINDER" (2026). Civil Engineering Theses. Paper 26.
http://hdl.handle.net/10950/5116