Role of mineral filler in asphalt mixture

Mineral filler, fine-grained mineral particles naturally present in or manufactured and added to aggregates play a significant role on the performance of asphalt mastic and asphalt mixtures. A clear understanding of effects of filler on the properties of asphalt paving mixtures is critical to ensure a good asphalt mixture design and its field performance. In this study, the basic properties of mineral filler, mainly including physical and chemical properties, were first reviewed and followed by the effects on mastic and mixture performances. This review finds that particle size distribution and specific surface area are the two most important physical characteristics for fillers in terms of its impact on mastic performances. Fillers, including diatomite, hydrated lime and cement, can improve the high temperature and durability performances of mastic and mixture. However, fillers, like glass powder, steel slag and bentonite, have a detrimental effect on the low-temperature performances. It can be concluded that it is important to carefully select the mineral filler type and proportion in order to improve the asphalt mixture performances.