Reflective Cracking Performance Evaluations of Highly Polymer-Modified Asphalt Mixture

Highly polymer-modified (HP) asphalt has been shown to enhance asphalt mixture performance. To evaluate its effectiveness in resisting reflective cracking, this study conducted dynamic modulus tests, cyclic fatigue tests, and overlay tests at three temperatures (4°C, 10°C, and 18°C) and compared the performance of HP mixtures against a control mixture. In addition, digital image correlation (DIC) has been used in the overlay test to capture crack growth. Apart from laboratory tests, simulations were conducted with two overlay thicknesses (3.81 and 7.62 cm) and two sets of climate inputs (isothermal and real) to assess the reflective cracking performance of HP at the structural level. The experimental results demonstrate that despite the selected two mixtures having similar modulus master curves, the HP mixture exhibits better resistance to reflective cracking compared with the control mixture. Specifically, predictions of the number of cycles to failure ($N_f$) by the simplified viscoelastic continuum damage (S-VECD) model, based on cyclic fatigue tests, indicate that the HP mixture has longer $N_f$ values across all selected temperatures. In overlay tests, at 4°C, the HP mixture shows comparable crack growth to the control mixture, whereas at 10°C and 18°C, the HP mixture demonstrates slower crack propagation. Furthermore, increasing the temperature tends to extend $N_f$ in both the cyclic fatigue test and the overlay test. The structural simulation results indicate that the overlay thickness has a significant impact on the predicted reflective cracking distress. When the overlay thickness is 3.81 cm, the two materials perform similarly based on the simulated output with respect to fatigue reflective cracking.