No abstract

No abstract

No abstract

No abstract

Weak bonding between layers of pavement leads to damages on the composite pavement. Bonding plays an important role in the durability and maintenance of composite pavement layers. The present study evaluates the factors effective in bond strength of the interface between concrete and asphalt pavements. The factors considered for this purpose include steel slag percentage in the concrete pavement, different types of modified bitumen, and rates of tack-coat. To measure the bond properties, direct shear and shear fatigue tests were carried out. In addition, texture depth and abrasion resistance were used in accordance with EN 1338 standard to measure the roughness properties of concrete pavement. The test results showed that 50% replacement of steel slag with aggregate resulted in an increase in physical properties and texture depth of concrete pavement. Moreover, the results of the shear strength test of composite pavement revealed that the optimal rate of using tack-coat varies between 0.6 and 0.9 l/m 2 and depends on the type of tack-coat. Finally, a higher shear strength was obtained for crumb rubber bitumen containing hydrated lime compared to crumb rubber modified bitumen and control bitumen.

Adhesion of composite pavement plays a significant role in the durability and maintenance of this type of pavement. The present research aims to assess the bonding and fatigue performance of rigid–flexible composite pavements through laboratory testing at different tack coat application rates. Three types of modified bitumen, crumb rubber-modified bitumen containing hydrated lime (CR/HL), crumb rubber-modified bitumen containing natural zeolite (CR/NZ), and crumb rubber-modified bitumen (CRMB), were selected as the tack coat. Shear fatigue and direct shear tests were utilized to assess the bonding properties of tack coats. The study also examines the behavior of modified bitumen by examining its viscosity, rheological properties, and performance grade. The results show that CR/NZ exhibits better performance in rheological behavior and at various temperatures compared to CR/HL and CRMB. Also, depending on the type of tack coat, shear strength tests show a range of 0.6–0.9 l m−2 as the optimal tack coat dosage. Finally, based on the optimal tack coat, shear strength ratings for various bitumen types may be classified as CRMB < CR/HL < CR/NZ.