Streamlining Uniaxial Cyclic Fatigue Testing of Asphalt Mixtures Using a Mechanical Clamping System

Abstract

This study presents a patented collet–chuck-based clamping system for uniaxial cyclic fatigue testing of asphalt mixtures using small specimen geometry. Conventional specimen preparation is time- and resource-intensive, requiring precise cutting and the use of epoxy adhesives to mount specimens onto loading platens. These steps are critical for test success and typically require highly trained personnel, and they introduce delays because of epoxy curing. The proposed mechanical clamping system eliminates the need for cutting and epoxy adhesives, which allows rapid, repeatable specimen mounting, streamlining the workflow and reducing testing time. The system is compatible with a standard asphalt mixture performance tester and can be fabricated using commercially available, off-the-shelf components. To evaluate its applicability, eight asphalt mixtures from three different states were tested using the conventional glued-end-plate method and the collet–chuck clamping system. The mixtures covered a wide range of material characteristics, including different nominal maximum aggregate sizes (NMAS), binder types (unmodified, polymer-modified, and highly polymer-modified), binder contents, and reclaimed asphalt pavement percentages. The results showed strong agreement between both methods, with similar damage characteristic curves and comparable normalized variance index v _norm values. The collet–chuck system produced improved v _norm values in five of the eight mixtures. In addition, no statistically significant differences were observed in the failure criteria based on pseudo stiffness versus time curve, and apparent damage index parameter between the two systems, confirming that the proposed clamping approach is a viable alternative for uniaxial cyclic fatigue testing without compromising test integrity or results validity.