Effect of Modifying Aggregates by Rap and the Simultaneous use of Adhesives for the Stabilization of a Sandy Pavement Subgrade

The improvement, reconstruction and repair of roads in recent years have increased the content of recycled asphalt in pavements. Using these materials in road construction projects because they reduce the costs, will also be of great help in improving environmental issues. In the present study, dune sand, which can be found in most desert area soil but does not have proper strength and loading capacity for a subgrade, was used. In order to increase the strength parameters of dune sand, various contents of cement and recycled asphalt were examined in California Bearing Ratio (CBR) and compressive strength tests. The results showed that the addition of cement and recycled asphalt can increase compressive strength and bearing capacity and reduce rupture deformations. In a stabilized sample with 27.5% recycled asphalt, increasing the cement from 7.5 to 12.5% increased the compressive strength by 1.045 times, which is the highest amount of change in the samples studied. The maximum CBR and minimum rupture deformations are related to 35% of the recycled asphalt and 12.5% of the cement. The predicted functions of the compressive strength, deformation and CBR depend on two variables of the cement content; the recycled asphalt was then calculated using the response surface method