Investigation of the performance of modified stone mastic asphalt according to the normal wearing course

In this research, local crushed materials of (Zakho) City crushers and normal bitumen from (Erbil) City and Filler from (Kwashi) industrial area in (Duhok) City were used. In addition, some imported materials were used, SBS, Fiber Cellulose and Superplast (SP) from Italy. Initially the physical properties of bitumen were improved through the addition of SBS and Superplasts individually and special tests of BG grade such as (DSR, RTFOT, PAV, BBR, Elastic Recovery, Softening Point…etc.) After the results were obtained, SBS showed more susceptibility than Superplast to improving the properties of bitumen. Therefore, the bitumen was improved with SBS used in Stone mastic asphalt (SMA) equation. After the best modified bitumen was selected (normal bitumen + SBS), a new stage was started in this research, namely the designing of equations for asphalt mixtures of the surface layer. Two equations were designed in this research. The first equation is to design the normal hot mix asphalt (BSK) mixture using unmodified bitumen and the second equation is the design of a Stone Mastic Asphalt (TMA) mixture using SBS polymers for modifying. The Marshall design method were used for both equations and all the design steps and tests are prepared in the construction materials laboratories in Duhok City. After conducting tests on these two mixtures especially the Hamburg wheel track test, it was reached the objective of this research, which is to find a mixture that has the ability to resistant to loads tiers (rutting resistance) and weather conditions and increase the life of the layer. All these specifications include in the Stone Mastic Asphalt (TMA) mixture.