Use of Asphalt Modified with Waste Material as the Tack Coat on the Interface between the Binder and Wearing Courses

Asphalt pavement consists of multiple courses, and a tack coat between the courses to ensure that these courses are properly bonded to each other is used. Generally, asphalt binder, asphalt emulsion, and cutback asphalt as the tack coat to ensure the bonding between the pavement courses are used. For the first time, to the best of our knowledge, in this study, the use of asphalts modified with bio-oil obtained from pyrolysis of waste recycled polypropylene in granular form as the tack coat on the interface between binder and wearing courses in laboratory conditions was examined. In order to evaluate the performance of double-layered asphalt samples containing a tack coat, strengths after the freeze-thaw test the indirect tensile strength (ITS), tensile strength ratio (TSR), and interfacial bond strengths of double-layered asphalt samples were calculated. Also, this study examined the influence of different factors [tack coat type (50/70 asphalt and asphalts modified with PPB at ratios of 1%, 2%, and 3%), application ratios (0.15, 0.30, and 0.50 L/m2), and cleanliness conditions of binder course] on the performance double-layered asphalt samples containing tack coat. Results indicate that the double-layered asphalt samples containing asphalt modified with PPB at a ratio of 2% at an optimum application ratio of 0.30 L/m2 a tack coat have the highest ITSdry value and interfacial bond strength, the ITSwet and TSR values of double-layered asphalt samples decreased as the number of freeze–thaw cycles increased, and the tack coat material, application ratios, and cleanliness conditions are affected ITS, TSR, and interfacial bond strengths of double-layered asphalt samples containing tack coat.