Comparison of Unconventional and Conventional HMA Mixes’ Performance in North Dakota

Due to its extreme weather conditions of long cold winters and short hot rainy summers, asphalt pavement design and construction in North Dakota has been challenging. Therefore, special modifiers are needed to provide HMA mixes with stability, durability, and acceptable compaction workability during late summer paving. The main objective of the study was to test the performance of a typical (conventional) North Dakota HMA mix with a special additive (Titan 1867) and compare it to the performance of the conventional mix without the additive (control mix). The asphalt pavement analyzer (APA T 340), AASHTO T 283, and compaction aid tests were performed to determine the mixes’ stability (rutting resistance), durability (moisture sensitivity, i.e., stripping), and late season paving (workability), respectively. A total of 12, 16, and 18 specimens were used for rutting resistance, moisture sensitivity, and compaction aid tests, respectively. Specimens for compaction aid were compacted at 275^oF, 245^oF, and 215^oF. Research results showed that mixes with Titan 1867 proprietary additive outperformed the conventional mixes (without additives) in all three performance measures. The unconventional mix (Titan 1867) did better than the control mix in rutting and moisture sensitivity resistances by 4.7% and 22.4%, respectively. For compaction aid, the unconventional mix consistently had lower air voids than the control mix at same compaction temperatures, indicating better compactibility.