Unraveling the Strength Secrets: How Polypropylene Fiber-Reinforced Asphalt Mixtures Defy Fracture

The semi-circular bending (SCB) and Indirect Tensile Asphalt Cracking Test (IDEAL-CT) are considered primary techniques recommended for assessing the fracture characteristics of asphalt mixtures under intermediate temperature conditions. The way specimens are prepared represents a fundamental distinction between the two testing techniques. SCB test is somewhat intricate and significantly limited by the specimen preparation steps, which include cutting and notching; the evolved IDEAL-CT test, in contrast, does not necessitate elaborate cutting and notching procedures. In this paper, the correlation between various fracture parameters measured from SCB and IDEAL-CT tests for asphalt mixtures reinforced with different dosages of polypropylene fibers was evaluated. The study included a comparison of the parameters of crack resistance and stiffness indexes based on specimen preparation, variability, and the effect of polypropylene fiber doses. The flexibility index and cracking resistance index showed a high linear correlation (R² = 0.86) and (R² = 0.84), respectively. The results of notched specimens in the SCB test exhibited greater variability in all fracture parameters results compared to the results of the IDEAL-CT test. The simplicity of preparing specimens primarily supports the IDEAL-CT test as a laboratory method for assessing the fracture characteristics of asphalt mixtures. The inclusion of varying amounts of polypropylene fibers has proven to significantly influence the values of fracture parameters in the asphalt mixture.