Performance Characterization of Half Warm Mix Asphalt Using Foaming Technology

Abstract

The objective of this study was to evaluate the moisture susceptibility, rutting, and fatigue resistance of laboratory-made half warm mix asphalt (HWMA) mixtures containing moist aggregates and recycled materials such as manufactured roofing shingles and reclaimed asphalt pavement (RAP). The test properties evaluated in this study included weight loss (%), indirect tensile strength (ITS), tensile strength ratio (TSR), wet flow, wet toughness, percent toughness loss, rut depth of dry and wet conditioned specimens, rut index, and beam fatigue life. The experimental design in this study included the use of foaming technology and three hydrated lime contents (0, 1, and 2% by weight of aggregate), three aggregate sources (designated as A, B, and C), three fractioned RAP sources from the same aggregate sources, and one PG 64-22 binder. A total of 27 mixtures was designed, and a total of 120 ITS samples, 162 asphalt pavement analyzer (APA) samples, and 36 fatigue beams were tested in this study. Results indicated that the addition of recycled materials such as RAP or roofing shingles can be effectively employed in HWMA mixtures, which did not reduce wet ITS and TSR values, although the compaction temperature was only 85°C. The influence of the moist aggregate used in HWMA on rut depth can be neglected and even results in a better rut resistance when incorporating recycled materials. Stiffness values of mixtures with recycled materials were generally dependent on the aggregate type. Based on the statistical analysis for the selected aggregates, no significant difference in fatigue life was observed for mixtures with recycled materials and control mixtures.