Effect of Aggregate Shape on Skid Resistance of Compacted Hot Mix Asphalt (HMA)

Characteristics of pavement surface play an important role in both the safety and comfort of drivers. Inadequate friction or skid resistance can lead to road accidents due to skidding. Aggregates properties such as size, shape, texture and gradation play an important part in providing friction or skid resistance on a pavement surface. This paper evaluates the effect of coarse aggregate shape on the skid resistance of compacted asphalt concrete mixtures. Three different mixes of ACW20 were designed using different shape of coarse aggregate: angular, elongated and flaky. Laboratory study was performed on the compacted wearing course mixture to evaluate the effect of aggregate shape on its properties. The performance evaluation measured included skid resistance, Marshall Stability and flow. The results of this study show that the strength and skid resistance varies with aggregate shape. The angular shape demonstrated the best skid resistance whereas mixes with flaky aggregates were shown to have the lowest stability and skid resistance.