Laboratory Investigations on Surface Characteristics of Different Asphalt Mixtures: Effect of Temperature, Surface Condition, Asphalt Content, and Compaction

Surface characteristics of the surface course in the pavement (highways and airfield) play an important role in ensuring safety of the road users under various conditions. The wet and contaminated runway pavements are known to contribute up to 40% toward runway veeroffs’ accidents. In general, the frequency of runway veeroff accidents is highest in the runways provided with dense asphaltic concrete (DAC) as wearing course. In addition to DAC, there are several asphalt mixtures, with the potential of being used as a surface course such as stone matrix asphalt (SMA) and open-graded friction course (OGFC). In this study, laboratory investigations were conducted on surface characteristics of DAC, SMA, and OGFC mixtures to understand the effect of temperature, surface condition (dry/wet), asphalt content, and compaction method adopted. The British pendulum number (BPN) and mean texture depth (MTD) were determined for different mixtures considering different experimental variables. The wet surface condition was more significant in reducing the BPN in DAC unlike SMA and OGFC. The BPN was found to be significantly depended on the temperature and asphalt content. The asphalt attains the shape of texture of aggregate at low temperature due to contraction and hence depicted higher BPN unlike high temperature. The temperature change was able to address higher degree of variability in BPN compared to asphalt content. However, as the thickness of asphalt coating increased around aggregate (OGFC), effect of temperature slightly reduced. The compaction method although found to be significant in affecting BPN, its contribution in variability was low.