The scarcity of high-quality granular materials has led to exploring alternatives like fly ash (FA), an industrial byproduct of coal-fired power plants. Utilizing FA in pavement construction can reduce the reliance on crushed stone aggregates, conserving energy and protecting the environment. However, its use in structural layers (base and subbase) is limited due to fine particles that make it brittle when stabilized. To address this, stone dust (SD) and aggregates (AG) were mixed with FA (noted FA-SA) before cement stabilization to improve gradation and strength. Polypropylene fiber (FI) was added to enhance reinforcement and reduce brittleness. Fatigue failure, caused by repeated loading, is the primary mode of failure in stabilized layers, making the development of a fatigue performance model critical for Mechanistic-Empirical pavement design. This study investigated the fatigue performance of cement-stabilized FA-SA mixtures using cyclic indirect tensile tests. Experimental evaluations, conducted with and without fiber reinforcement, included indirect tensile strength, resilient modulus, and fatigue behavior using a servo-hydraulic testing machine. Results showed three stages of stiffness reduction, with a final modulus drop of 15%-30% compared to the initial modulus, indicating brittle behavior under stress-controlled conditions. A strain-based fatigue model was developed, with strain damage exponents for FA-SA composites stabilized with 4%-6% cement and 0.25%-0.35% fiber ranging from 4.37 to 4.55. These findings enhance the understanding of fatigue performance in FA-based stabilized layers, supporting the design of sustainable road infrastructure. • Three stages of stiffness reduction was identified for fiber-reinforced cement-stabilized fly ash aggregate mixture. • Stiffness modulus reduced to 15%-30% compared to the initial modulus, indicating brittle behavior under stress-controlled conditions. • Strain-based fatigue models were developed.
Mohanty et al. (Wed,) studied this question.