The influence of the mineral filler on the adhesion between aggregates and bitumen

The loss of adhesion is a major mechanism of physical distress in hot-mix asphalt (HMA) because it could reduce the durability of HMA. In this study, active and passive adhesions between the aggregates and the bitumen that are part of HMA were analysed. As part of the analysis, the Boiling Water Test and measurements of the mixing times were conducted. Four aggregates (hornfels, feldspatic schist, gabbro and dolomitic calcite) and five fillers (from natural aggregate, from natural aggregate+1% hydrated lime, commercial limestone, grey Portland cement and fly ash) were used to generalise the conclusions. The experimental results indicated that the use of filler, particularly the grey Portland cement, improves the passive adhesion. The results also indicated that the use of natural filler results in the worst active adhesion. The statistical analysis confirmed the observed results and indicated that active and passive adhesions are not related.