Effects of fillers on properties of asphalt-concrete mixture

The role of filler on the mechanical performance of asphalt-concrete mixture was investigated. Three wearing course (W3B) mixtures incorporating granite, hydrated lime, and kaolin as filler fractions were evaluated by the Marshall mix design method to determine their optimum asphalt content. The use of hydrated lime or kaolin as a filler requires more asphalt because of their relatively higher specific surface area. The highest stiffness performance was found for W3B-hydrated lime, followed by W3B-granite, and W3B-kaolin mixtures. W3B-hydrated lime and W3B-kaolin mixtures exhibited higher deformation resistance than that of W3B-granite mixture. The results showed that the presence of filler in an asphalt-concrete mixture affects the mixture's performance in three ways: filler influences the amount of asphalt content, filler affects the workability during mixing and compaction, and the resultant properties of asphalt-filler mastic contribute to the mixture's performance. The results show that the properties of the filler determine its interaction with asphalt and its contribution to the mixture's performance.