Investigating the Rutting and Top Down Cracking of Asphaltic Surface Layer of Composite Pavement with Roller Compacted Concrete Base by Finite Elements Method

In this research, rutting and top-down cracking of asphaltic layer in composite pavement with RCC have been investigated. To this end, 3D models of pavement have been made in Finite Element software of ABAQUS. Performance of 5 different asphaltic mixtures has been evaluated and compared. In addition, the effects of using different geogrids in different depths of asphaltic layer on the rutting and top-down cracking have been investigated. The effects of asphalt surface and RCC base thickness on the rutting and top-down cracking has been studied. Results show that type of mixture in surface layer is significantly important in rutting and top-down fatigue cracking. In addition it has been found that placing the geogrid at the mid-depth of asphalt surface decreases the rut depth, and, pacing that at the bottom of asphaltic layer is not effective on the rut depth. The effectiveness of geogrid is found to be dependent on the stiffness of geogrid, type of mixture and thickness of asphaltic layer. Also, placing the geogrid in the mid-depth of asphaltic layer decreases the top-down fatigue life, and placing that at the bottom of asphaltic layer is not effective on the fatigue life. The results of analysis show that rut depth increases with increasing the thickness of asphaltic layer, but is independent of the thickness of RCC layer thickness. The maximum tensile strain at the surface of asphaltic layer is found to vary with the thickness of asphaltic surface and RCC layer. However, the variation does not follow a trend.