Construction Technology and Pavement Performance of Dry-Mix Polyurethane Modified Asphalt Mixtures: A Case Study

Polyurethane Modified Asphalt Mixture (PUAM) has been confirmed to possess good engineering properties and is a potential replacement material for pavement construction. This study aimed to provide guidance for the promotion and application of PUAM in pavement engineering by exploring the construction technology and verifying the practicality. Dry-mix PUAM (DPAM), wet-mix PUAM (WPAM), and SBS-modified asphalt mixture (SBSAM) were prepared. After systematically investigating the construction process of the three mixtures, their pavement performance was comparatively evaluated. Subsequently, the DPAM was utilized to construct the trial pavement, and the completed pavement was tested and evaluated. Furthermore, the costs of the DPAM and SBSAM were analyzed. The results reveal that the construction technology had a significant effect on the mechanical properties of the mixtures. Compared with SBSAM, the optimum mixing temperature and time of the DPAM and WPAM were reduced. The mixing temperature, mixing time, and hitting number were recommended to be 160 degrees C, 60 s, and 75 times for the DPAM. Fourier Transform Infrared Spectroscopy tests confirmed that the PU reacted sufficiently in the binder. The DPAM exhibited good overall pavement performance, and its low-temperature cracking and fatigue resistance were significantly better than that of SBSAM. Meanwhile, all the pavement indexes constructed with DPAM met specifications, and the performance and service condition of the test road after the operation will be paid attention to continuously. Additionally, the cost of DPAM was close to that of SBSAM, and the more straightforward construction process and better pavement performance of DPAM could reduce the construction energy consumption and maintenance frequency, which was meaningful for promoting the scale application of DPAM and the sustainable development of transportation infrastructure.