Investigating the Relation among British Pendulum Number, Mean Texture Depth and Asphalt Content in Hot Mix Asphalt

Pavement surface texture and its skid resistance are two key safety parameters of highways, which both are influenced by pavement characteristics. This research is done on a newly constructed asphalt pavement (Qom-Garmsar freeway) in Iran. The goal is investigating the relation between skid resistance and pavement texture in order to asphalt content changes in Hot Mix Asphalt. Mean Texture Depth (MTD) and British Pendulum Number (BPN) are being used to quantify pavement texture and skid resistance, respectively. The results show that the asphalt content has a significant effect on MTD and consequently, BPN in loaded pavements, as well as non-loaded pavements. The result showed that the lowest BPN value obtained, when the asphalt content is about the optimum value. Moreover, it is demonstrated that using asphalt contents less and more than the optimum value, results in BPN improvement. Asphalt content increasing, around optimum value, leads to MTD decrease. The results also show that by increasing the MTD, the BPN decreases to 75 (in MTD value of 0.62 mm) and then increases.