Development of a rutting index parameter based on the stress sweep rutting test and permanent deformation shift model
Amir Ghanbari, B. Shane Underwood, Y. Richard Kim
Abstract
The use of index parameters to evaluate the performance of asphalt mixtures has become an important process for making informed pavement material decisions. These index parameters are indicators of asphalt mixture performance and thus are widely used in the asphalt paving industry. This paper presents a new rutting index parameter to assess the rutting resistance of asphalt mixtures using the stress sweep rutting test and the permanent deformation shift model. The proposed parameter, referred to as the Rutting Strain Index (RSI), is novel in that it integrates material testing and structural simulations. To develop the RSI index parameter, more than 70 mixtures from different geographical locations that exhibit a wide variety of performance were evaluated. The results show that the RSI is able to capture the effects of mix design factors, such as RAP content, binder content, and volumetric properties. Furthermore, a set of RSI threshold values are proposed for different allowable traffic levels in terms of rutting. The RSI can be employed by agencies as a tool for performance engineered mix design and quality assurance purposes whereby agencies will be able to accept or reject a mixture based on RSI thresholds.