New Generation HMA Mix Designs: Accelerated Pavement Testing of a Type C Mix with the ALF Machine.

摘要

Recent changes to the Texas hot-mix asphalt (HMA) mix-design procedures, such as the adaption of the higher-stiffer performance-grade asphalt-binder grades and the Hamburg test, have ensured that the mixes that are routinely used on Texas highways are not prone to rutting. However, performance concerns have been raised with these HMA mixes, which are now drier, more difficult to compact, and more susceptible to premature cracking. This is particularly problematic with the dense-graded mixes (Type C and D) that are widely used throughout the state of Texas. Several new ideas have been under consideration to either: (a) modify the existing HMA mix-design criteria and/or include new and simpler cracking test procedures, or (b) develop new generation HMA mix-design methods that will optimize HMA field performance, particularly with respect to cracking. In this study, two HMA mix-design methods, namely the traditional Texas gyratory (TG) and the proposed balanced mix design (BMD) were comparatively evaluated in the laboratory and then validated in the field using accelerated pavement testing (APT) with the accelerated loading facility in Louisiana. A typical Texas dense-graded Type C mix, designed using both the TG (herein called the Control) and the BMD (herein called the Modified) methods, was utilized. This report provides a detailed documentation of the laboratory and field APT test results of the Type C mix, both the Control and Modified designs, respectively. Compared to the traditional TG method, the study findings indicated that the proposed BMD method yields a richer HMA mix design with higher asphalt-binder content and superior crack resistance and constructability (workability and compactability) properties, respectively.