Evaluating the effects of mineral filler on the volumetric properties of HMA mixtures based on superpave mix design specifications

Volumetric properties of hot mix asphalt (HMA) are necessary requirements to ensure good performance for asphalt mixtures. However, volumetric properties appear to be directly influenced by various factors including the mixture grading, aggregate surface characteristics and compaction energy. This research is conducted to evaluate the influence of mineral filler on the volumetric properties of HMA. Two types of mineral fillers with three filler percentages were chosen to examine the effect of filler on various volumetric properties including voids in mineral aggregates (VMA), voids filled with asphalt (VFA), dust to binder ratio (Dp), and others. The obtained results Indicated that the optimum asphalt binder content, VMA, and VFA decrease as the filler content Is increased. Compared to other volumetric properties that were reduced when filler content increased, Dp proportion behaved inversely for both filler types in which Dp proportion increases when the filler content is increased. HMA mixtures that includes dust plant filler had the higher values of VMA, VFA, and optimum asphalt content (OAC) compared to the hydrated lime. The addition of filler with 2.5% percentage is very successful for both filler types due to satisfying all Ministry of Transportation Ontario (MTO) requirements for volumetric properties of HMA. Based on MTO specifications, the addition of 2.0% filler seems to be unsuccessful for both filler types due to lowering the Dp ratio. Mix design with 3.0% filler was also unsuccessful because of the lower value of OAC meaning that the mix is dry and there is insufficient asphalt binder to coat the aggregate particles.