Temperature Normalization of Flexible Pavement Response Measurements

Full-scale accelerated flexible pavement testing often features embedded instrumentation to characterize the structural response of the pavement to changing external conditions such as tire loading, vehicle speed, temperature, aging and pavement condition. These measurements, such as horizontal tensile strain in the asphalt layers and compressive stresses in the underlying foundation layers, are often linked to distress development. A common challenge with these measurements is the confounding effect that temperature has on understanding the other effects and the need to normalize measurements to a standard reference temperature. This paper describes the approach to temperature normalization developed at the National Center for Asphalt Technology Pavement Test Track. The approach utilizes an exponential power function to develop section-specific temperature correction factors that effectively normalizes strain and pressure data to a standard reference temperature. Once temperature normalization has been completed, trends in the data related to aging and pavement damage are more easily identified and understood. Several case studies from prior Test Track investigations are presented to illustrate the normalization process and data interpretation.