On the impact of the filler on the complex modulus of asphalt mixtures

Mineral fillers have been used in asphalt mixtures from their very beginning. Rapidly, formulators observed that the filler could have a strong influence on the final mixture. Nowadays, mineral fillers are essentially characterised by their ability to stiffen the bitumen, leading to the development of the celebrated “Rigden air voids” RV (EN 1097-4), now the corner stone of the European specifications for fillers in asphalt mixtures. If the way the filler modifies the rheological properties of mastics is now well described, the relationship between mastic and mixture properties remains poorly understood. Therefore, this paper describes a systematic study on the impact of increasing filler contents on asphalt mixtures. Experimental results are presented for two very different asphalt mixture formulas, a regular semi-dense Asphalt Concrete (AC) and an open-graded AC for very thin layers (BBTM). The complex modulus of each formula was measured as a function of filler content with two materials having very di...