Synthesis and Performance Evaluation of Modified Asphalt–Based Trackless Tack Coat Material

AbstractTo minimize problems of poor bonding and tracking in common tack coats, modified asphalt–based trackless tack coat material (TTCM) was prepared by adding styrene–butadiene–styrene, uintaite mastic asphalt, ethylene-vinyl acetate (EVA) copolymer, and polyethylene (PE) wax to No. 50 base asphalt under high-speed shearing, stirring, and high-temperature static conditions. Through a time-saving orthogonal test and scientific range analysis approach, the optimal dosage of different modifiers determined was No. 50 basic asphalt:SBS:uintaite mastic asphalt:EVA:PE wax as 100:5:6:6:6. Mechanical tests of TTCM revealed track-free time of less than 1 min at 25°C and trackless nature at 60°C. At an optimum dose of 0.5 kg/m2, the shear strength of TTCM reached 0.45 MPa, which was 120%–145% higher than many conventional tack coat materials. Dynamic shear rheological testing revealed higher complex shear modulus (G*) and smaller phase angle (δ) of TTCM compared with that of base asphalt. Scanning electron microscopy and fluorescence microscopy tests showed distinct uniformly dispersed modifiers and reticulated fine lines in TTCM, which were important for the performance of TTCM. Based on Fourier transform infrared (FTIR) spectroscopy analysis, the proposed modification mechanism suggests that stronger adhesive bonds in TTCM than cohesive forces within the hot-mix asphalt layer contributed to its trackless nature. Each modifier contributed toward the improved high-temperature stability and low-temperature flexibility of the TTCM. Due to its outstanding mechanical performance, cost-effectiveness, and green synthesis approach, the currently designed novel TTCM can be deemed as a potential candidate for highway and construction industries.