Evaluation of temperature influence on friction measurements

Many aspects influence the skid resistance of a pavement surface including surface texture, tire characteristics, vehicle operations, and environmental factors. The objective of this paper is to quantify the temperature influence on the skid number of asphalt pavement surfaces when measured by the locked-wheel friction tester. Specifically, this study aims to determine an adjustment factor for friction readings to a standard reference temperature, removing the seasonal temperature variations influencing measurements. This allows agencies to improve the comparison of pavement sections and to provide a more objective assessment of pavement conditions for safety. The friction database employed is from the National Center for Asphalt Technology Test Track facility. The data includes friction measurements with a locked-wheel trailer on sections from the 2000 and 2003 research cycles. The approach calculates the temperature adjustment factor, CT, from a grouping of the data by temperature values at the time of the measurements. The results show that it is possible to define a reference temperature to adjust friction measured at any other temperature value. The reference temperature identified is between 19.5°C (67.1°F) and 20.2°C (68.4°F). The study concludes that when testing, if the air temperature is greater than the reference temperature, the friction reading is biased by a positive quantity. Therefore the adjustment factor, CT, reduces the measured friction, whereas for measurements performed at temperatures lower than the reference temperature, CT increases the measured friction. Language: en