Characterisation of asphalt pavement surfaces using torque measurements

Abstract

Continuous increase in traffic volume in the recent years has resulted in greater surface friction loss of asphalt pavements. While the literature presents several ways of aggregate and asphalt mix screening to ensure that surface characteristics are at an acceptable level of friction to control skid-related accidents, the recommended polishing tests using different accelerated polishing devices are time-consuming and to some extent labour-intensive. Therefore, it is imperative that existing polishing devices be improved to shorten the test duration to a level desired by the industry as well as state and federal agencies. This paper aims at addressing this improvement that uses power unit (or motor) to generate energy enough to rotate the polishing disk at constant rotational speed while being pressed against the specimen surface, then read the power needed from the display screen for the following steps. Multiple verification techniques including comparison studies and statistical analyses were used to examine the validity of this improvement. It was found that data collected by the power unit was repeatable and able to precisely detect surface deterioration history for different asphalt mixes with different polish susceptibility in a manner similar to conventional friction and texture-measuring devices. Hence, aggregates and mixes were classified based on their surface frictional properties. Additionally, results from this study correlated well with results from other studies using conventional methods. Most importantly, it was found to be possible to cut down the polishing test time using torque values in lieu of conventional surface quantification methods.

Keywords:

• Asphalt pavements
• friction
• texture
• torque
• polishing
• ANOVA