Aging Characteristics of a Colored Ultrathin Overlay

The purpose of this work is to improve understanding of the aging characteristics of colored ultrathin overlay. In this study, a colored ultrathin overlay was prepared with a binder produced with a waterborne epoxy resin (WER) and styrene butadiene styrene-modified emulsified asphalt (SBS-EA). As part of this study, two conventional ultrathin overlays were prepared to examine the performance feasibility of colored ultrathin overlay compared to traditional overlays. An indoor artificial accelerated oxidative aging was involved in this work to resemble the outdoor natural aging of pavement. The variation of functional groups in asphalt binder due to aging effect was quantified using Fourier transform infrared spectroscopy (FTIR). In addition, pre- and postaging shear strength, cooling effect, skid resistance, permeability, and wearing resistance of the colored and conventional thin overlays were evaluated. The results showed that the number of endothermic functional groups, carbonyl (C=O) and hydroxyl (-OH) groups, in the binder increased with aging time, further resulting in a decrease in the cooling effect. After aging, the shear strength of the binder also decreased. The iron oxide red faded gradually, its reflectivity to sunlight decreased, and the cooling effect of the aged colored ultrathin overlay also decreased. However, the cooling effect of the overlay was leveraged due to the presence of iron oxide red. The shear strength, skid resistance, permeability, and wearing resistance of the overlay decreased to different degrees after aging, but the aging resistance of the colored ultrathin overlay was better than that of the traditional overlays due to the presence of the WER and iron oxide red. Because the aged colored ultra-thin overlay manifests promising cooling effect, bonding strength, and performance, it offers a good preventive maintenance strategy for pavement. (C) 2022 American Society of Civil Engineers.