Three-Dimensional Surface Texture of Asphalt Pavements Containing Reclaimed Asphalt Concrete
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The type, shape, and gradation of aggregate have significant influence upon surface texture and its durability. The properties of reclaimed asphalt pavement (RAP) are different from virgin aggregate. Previous research found that the presence of RAP influenced negatively the pavement surface terminal friction value and surface polishing rate. The objective of this research is to assess the impact of high content of RAP on pavement surface texture after five years of environmental and traffic loading. Field pavement textures were measured on sections with various percentages of RAP. The sections have been in service for five years at the time of testing. The three-dimensional (3D) surface texture is recovered by using a portable line-laser scanning device which has the ability to scan an area of 100 mm x 100 mm of pavement surface with a horizontal resolution finer than 0.05 mm, and vertical accuracy better than 0.1 mm. The recovered 3D texture heights are decomposed into five levels by using discrete wavelet transform to separate macro-texture from micro-texture. 3D texture indices were calculated and analyzed. These 3D texture parameters are indices of texture size both at macro-level and micro-level, spacing, distribution, and texture direction. Texture analysis showed that the macro-texture indices were better for sections with high RAP content than those with low RAP content at the time of testing, while micro-texture parameter shows equal or slightly higher value compared to control mixture. It was also found that the texture durability was slightly worse for high RAP content (50%) sections than those of lower RAP content sections. Pavement core samples were collected and characterized through creep compliance, indirect tensile test and resilient modulus. Laboratory results showed that as the amounts of RAP increases the rutting resistance increases, however, the resistance to low temperature cracking decreases as expected.