Document Type : Research Paper
Authors
1
Department of Civil Engineering, Am.C., Islamic Azad University, Amol, Iran
2
Faculty member, Islamic azad university, savadkouh branch, civil engineering department, Amol, Iran
3
Department of Civil Engineering, CT.C., Islamic Azad University, Tehran, Iran,
Abstract
The use of Nano-Al₂O₃ to enhance the durability of asphalt mixtures containing expanded clay aggregates (LECA) represents a sustainable and innovative approach in pavement engineering. In this study, 85–100 bitumen was blended with 0, 1%, 2%, and 3% by weight of Nano-Al₂O₃ using a high-shear mixer, and the bitumen was subjected to physical and rheological tests, including penetration, softening point, ductility, rotational viscosity, RTFO, PV, and DSR. Asphalt mixtures with 0%, 25%, and 50% replacement of LECA aggregates were evaluated through Marshall, dynamic creep, and fatigue life tests to assess the combined effect of these additives on mechanical properties, creep behavior, and fatigue resistance. The physical tests of bitumen indicated that Nano-Al₂O₃ addition improved the softening point, provided controlled stiffness, enhanced ductility, and increased viscosity. Rheological results showed that Nano-Al₂O₃ reduced mass loss and improved rutting and fatigue indices, indicating delayed cracking and increased pavement durability. Dynamic creep tests revealed that the incorporation of Nano-Al₂O₃ and optimal LECA replacement reduced cumulative strain and slowed the accelerated growth rate in the tertiary creep phase. Fatigue life tests demonstrated that the 25% LECA + 2%Al₂O₃ mixture exhibited the best performance, confirming that although elevated temperature and high stress levels accelerate fatigue damage, this mixture effectively mitigated these adverse effects and delayed deterioration. Regression modeling indicated that the percentages of Nano-Al₂O₃ and LECA aggregates had a significant impact (p < 0.05) on fatigue life. The models achieved high coefficients of determination (R² = 0.928, 0.947, and 0.937 for 0%, 25%, and 50% LECA, respectively), accurately predicting the fatigue behavior of the mixtures. These results demonstrate the suitability and generalizability of the models for the design of durable asphalt pavements.
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