Laboratory and Field Evaluation of Two Warm-Mix Additives in Connecticut and Validation of an Alternative Moisture Susceptibility Test

The first official state Warm-Mix Asphalt (WMA) pavement project in Connecticut was constructed between July 20th and 22nd, 2010 and it involved three experimental sections, i.e. one section with a conventional HMA (control section) and two WMA sections with different technologies, wax and foamed asphalt. All three sections are located on Route 70 in central Connecticut. The materials were collected in loose form and reheated and compacted in laboratory conditions (laboratory fabricated specimens). This paper discusses the effect of mix type on the results from several tests conducted in the laboratory, such as Semi-Circular Bending, Hamburg Wheel Tracking, Indirect Tensile, and Disk Compact Tension. The results from the WMA specimens are also compared against conventional HMA specimens. Finally, the paper presents the performance data from all three test sections after the first winter season and correlates these observations with the laboratory results. It was seen that all sections performed very similarly, however there were subtle differences between the WMA sections that may cause performance differences later in their lives. Additionally, this study examined the Moisture Induced Stress Test (MiST) as a means of identifying stripping potential in asphalt pavements. Material tested in the MiST included field samples from six Long-Term Pavement Performance (LTPP) test sections as well as field and laboratory compacted WMA from the Rt. 70 test sections. Wearing surface cores from the LTPP test sections were run through the MiST and water samples before and after the test were analyzed using Infrared Spectrometry. The warm-mix specimens were MiST conditioned and compared to the traditional Tensile Strength Ratio as well as the change in bulk specific gravities. The results were mixed results of HMA and WMA specimens. Furthermore, the spectroscopic analysis showed potential differences between the mixes