Temperature Effect on Frictional Properties of HMA at Different Polishing Stages

Both short-term and long-term variations have been observed in measured friction on pavement surface. These variations have been attributed to different factors, such as traffic, rainfall and temperature. Due to the fact that Hot Mix Asphalt (HMA) pavement surface and rubber tires are viscoelastic materials, it is believed that temperature may affect the measured frictional properties. Some researchers have found this effect to be significant; whereas, others have not. Therefore, the effect of temperature on the measured pavement friction remains to be further studied. This paper provides the results of a laboratory study aimed at evaluating the effect of temperature on the measured frictional properties of the HMA surface. The British Pendulum Tester (BPT) was used to measure friction of HMA surfaces at different polishing stages and different temperatures. Statistical analyses were performed to quantify the effect of temperature on the measured friction numbers. The main conclusion of this paper is that temperature is statistically significant in affecting the measured friction values. However, for agencies who desire to record skid number (SN) at a reference temperature for a long-term monitoring purpose, this paper provides a method for converting SN at a given temperature to the SN at the reference temperature.