Aggregates make up approximately 93 to 96 percent of asphalt mixes by weight. The shape and angularity of aggregates particles has a direct impact on the quality of asphalt. Previous research suggests that mixes with cubical shaped aggregate particles perform better than mixes with elongated particles. This project investigated stone matrix asphalt (SMA) mixes as made in Auckland New Zealand to determine if observed performance could be related to these parameters and whether laboratory characteristics are consistent with this idea. Three similar SMA mixes were selected containing different primary aggregates. ASTM D3398 was used to measure shape and angularity. The mixes chosen were mixes currently being used in the Auckland region and have a significant performance history. APRG-18 testing of indirect modulus (MATTA), wheel tracking and retained tensile strength (TSR) were carried out. Orientation of the aggregate within compacted mixes was also characterised. The results show that shape and angularity of aggregate particles significantly affect performance characteristics. (a) For the covering entry of this conference, please see ITRD abstract no. E217099.
Samenvatting