Investigation of the usability of blast furnace slag as mineral filler material in stone mastic asphalt manufacturing

With the development of industry and the rapid increase in population worldwide, the rate of urbanization is also increasing. The need for transportation emerges as an indispensable element of the urbanization process. The vast majority of transportation worldwide is provided by road transportation. In order to increase both traffic safety and driving comfort on highways, the highway superstructure layer is covered with an asphalt layer thick enough to provide sufficient stability. Since the basalt rock used in the production of Stone Mastic Asphalt, which is used as a highway superstructure wear layer, has limited reserves, and the blast furnace slag, which is produced as a waste material after the processing of iron ore in our country, can be used as a mineral filler material in the production of Stone Mastic Asphalt, it is important both economically and environmentally and in terms of eliminating reserve scarcity. Blast furnace slag is the surface residues that accumulate on the surface of the melted metal during the melting process in iron or steel production. These residues precipitate and turn into solid form during the cooling of the metal that has become liquid at high temperatures. In this study, granodiorite aggregate was used as coarse and fine aggregate in Stone Mastic Asphalt mixtures. Ground blast furnace slag, which is abundantly available as a waste material in our country, was used as a mineral filler material. In order to compare the effect of blast furnace slag on the strength of the TMA mixture, a TMA design prepared from aggregates obtained from Safalan quarry in Saray district of Tekirdağ was used. In the design made using Marshall design method, 3 pieces of briquettes with bitumen ratios of 5.7%, 6.2%, 6.5%, 6.7% and 7% were prepared for each different percentage and the optimum bitumen ratio was found to be 6.30%. In addition, indirect tensile strength of 88.1 and Schellenberger bitumen percolation tests were applied to the prepared briquettes and the result was found to be 0.026. According to the findings obtained, no negative results were encountered in the use of blast furnace slag as an alternative mineral filler material and it was concluded that blast furnace slag can be used as an alternative mineral filler material to granodiorite aggregate used as a mineral filler material.