Assessing the Performance of Overlay and Leveling Binder Courses in Traffic Circle Construction

Abstract: Traffic Circles play a crucial role in enhancing traffic flow and road safety by reducing conflict points and controlling vehicle speeds. However, the unique traffic dynamics at Traffic Circles, such as frequent braking, acceleration, and slow-moving traffic, subject the pavement materials to increased stress, leading to damage and early cracking. This study evaluates the performance of overlay and leveling binder asphalt mixtures used in the construction of a Traffic Circle. Utilizing Plant Mix Laboratory Compaction (PMLC) specimens, the research investigates stiffness, cracking resistance, and rutting resistance through IDEAL-CT and IDEAL-RT. Additionally, the study incorporates Tensile Strength Ratio (TSR), Cantabro Mass Loss, and binder extraction tests to comprehensively assess the mixtures’ durability and performance characteristics.

Results indicate that both layers exhibit low Cracking Tolerance (CT) indices, suggesting increased brittleness due to aging. However, the overlay mixture demonstrates higher Rutting Tolerance (RT) indices, indicating superior resistance to rutting. The TSR test results offer insights into moisture susceptibility, while the Cantabro Mass Loss test provides data on the mixtures’ resistance to abrasion and raveling. Binder extraction test results illuminate the properties of the recovered binder, offering valuable information about its aging characteristics and performance potential.

Fatigue life and rutting life simulations provide further insights into the longevity and durability of these mixtures. The simulations revealed that the overlay layer could offer an extended service life under repetitive loading conditions compared to the leveling layer. By comparing overlay and leveling course asphalt mixtures across multiple performance indicators, the findings guide future pavement design and maintenance approaches for Traffic Circles, aiming to reduce environmental impact and enhance overall infrastructure durability.