Determining physical and mechanical differences of asphalt specimens using Superpave and Marshall design methods

In recent years, as a result of excessive loads and the climate changes, deteriorations have occured on highways, that headed towards the development of new applications by highway engineers. In particular, extreme axle loads continue to deadlock against rutting problems. This problem is disturbing driving comfort and travel safety. Bitumen modification can be a solution to solve this problem; it can help to prevent deteriorations and crackings which occurs by climatic changes.Another reason for the deterioration of highways, in the existing design procedure is due to failure to comply with evolving technology. With this technology, there is a definite increase in the load carrying capacity of vehicles, tire pressures and axle loads. Marshall design method has been utilised for years and still being used in our country; is the preferred method of design. The compaction method used in Marshall design is not modelling exactly the process of actual rolling procedures. Instead, the new design methods have been developed, such as Superpave (Superior Performing Asphalt Pavements) which is more realistic than the other methods.In this study, we compared physical and mechanical differences of HMA (Hot Mix Asphalt) and polypropylene modified HMA, using Superpave and Marshall design methods. Especially repeated creep tests were carried out to understand the resistance to rutting. In addition, there is no standard Superpave design procedure for 100 mm diameter samples. The other purpose of this study is produce a new standard for this samples. Indeed, studies showed that the gyration number should be 40 for the medium traffic volumes. Additionally the samples produced by Superpave procedure were more resistant to permanent deformations. Therefore it's established that the new optimum bitumen content values will be lower and consequently there will be financial benefit gained in terms of bitumen.