Waste materials and by-products as mineral fillers in asphalt mixtures

Mineral filler has a significant effect on the asphalt mixtures performance. This paper presents the use of waste materials (marble and granite) and by-product material (steel slag) as alternative to the mineral conventional filler. A control mix with the limestone filler was designed by Marshall method then, a replacement of limestone filler by the waste and by-products materials was done. Two types of mastic asphalt samples were prepared (virgin and aged by the rolling thin-film oven) with the ratio of 1:1 (mineral filler/asphalt). The samples were tested in penetration, softening point and Brookfield rotational viscosity. Furthermore, the transition electron microscope for fillers and scanning electron microscopy for mastics tests were performed. Both virgin and RTFO granite mastics improved the penetration value; however, the marble mastics showed the highest softening point temperature and RV viscosity. Marshall results showed that mixtures containing waste marble yielded the highest stability. Moreover, results showed the ability of marble to improve the moisture damage resistance in terms of tensile strength ratio and loss of stability. Finally, the field performance was predicted using Quality-Related Specifications Software which is a simplification of the Mechanistic-Empirical Pavement Design Guide software. It was found that all materials enhanced rutting resistance compared to the traditional limestone filler.