Performance testing is an important tool to complement volumetric properties for improving asphalt pavement performance. Vermont Agency of Transportation (VTrans) began evaluating the Hamburg wheel-tracking test (HWTT) in 2015, the Illinois flexibility index test (I-FIT) in 2018, and the indirect tensile cracking test (IDEAL-CT) as another index-based test to investigate along with the I-FIT, as a step toward balanced mix design (BMD) implementation. An increase in the use of recycled materials in asphalt mixtures produced in Vermont was anticipated in their Standard Specifications for Construction. This study is an attempt in this direction. The tests were conducted on reheated plant mixtures sampled from paving projects in Vermont and the results were analyzed to (1) develop baseline rutting and cracking performance; (2) evaluate the effects of mixture properties on performance test results; (3) compare IDEAL-CT results and I-FIT results; and (4) compare performance test results with specification criteria proposed by VTrans for evaluating the rutting and cracking resistance of asphalt mixtures. Several mixture properties, viz., nominal maximum aggregate size (NMAS), binder grade, binder content, and recycled content, were found to have significant effects on mixture rutting and cracking resistance. The test results showed a direct correlation between FI and CTindex for the dataset of VTrans mixtures. The information from this research will help VTrans to achieve its goal to move beyond the use of volumetric properties for asphalt mixture design and acceptance and serve as an example for other agencies in exploring the implementation of BMD for improving asphalt pavement performance.

Performance testing has been recognized by state highway agencies and the asphalt paving industry as an important tool to complement volumetric properties for improving asphalt pavement performance. Thus, the Vermont Agency of Transportation (VTrans) began evaluating the Hamburg wheel-tracking test in 2015, Illinois flexibility index test in 2018, and indirect tensile cracking test in 2020 as steps toward balanced mix design (BMD) implementation. These tests were conducted on reheated common plant-produced asphalt mixtures for multiple shadow projects, and the results were analyzed to determine the typical production variability observed in the performance testing results. Production variability is important to assess potential specifications in field production, especially for statistical quality acceptance procedures, such as percent within limits. Based on the percent within limit analysis, most of the modified Type IVS (i.e., 9.5 mm) mixtures would be acceptable based on the proposed performance requirements, while those found not acceptable were close to meeting the performance requirements and would need minimal adjustments. The lot data was further examined to generate typical lot production variability values for potential use in specification development. The information from this research effort will help VTrans achieve its goal to move beyond solely volumetric properties for asphalt mixture design and acceptance and serve as an example for other agencies exploring the implementation of BMD for improving asphalt pavement performance.