Laboratory evaluation and digital image processing techniques in determining moisture susceptibility of reclaimed asphalt pavement mixtures
Date
2023
Authors
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Publisher
University of Delaware
Abstract
About 90% of all roads and highways in the United States (U.S.) are built with Hot Mix Asphalt (HMA). Due to growing demand, a shortage of aggregate, and a lack of binder supplies, Reclaimed Asphalt Pavement (RAP) has emerged as a critical component in HMA. RAP is used in asphalt pavement for various reasons, but the two most crucial reasons are economic savings and environmental advantages. Moisture damage, which is also called moisture susceptibility or moisture sensitivity, can be caused by the amount, quality, and type of materials in the asphalt mixture, as well as by environmental factors, construction details, and pavement design elements. Moisture damage causes the stripping of asphalt binder from the surface of the aggregate. Stripping impairs pavement performance and frequently leads to unanticipated increases in maintenance budgets. Several laboratory procedures have been developed to measure the moisture sensitivity of asphalt mixtures, some of which rely on subjective visual evaluation. Setting a pass/fail standard for these subjective tests can be challenging. This study first compares laboratory test results for HMA mixtures with varying amounts of RAP content using the Indirect Tensile Strength test (AASHTO T 283), Boil Test (ASTM D3625), and Hamburg Wheel Tracking Test (AASHTO T 324). Subsequently, digital image analysis using Python programming language and colorimeter readings were taken on laboratory test specimens to quantify the amount of stripping. Mixtures with higher amounts of RAP were found to be more moisture susceptible. Strong correlations were found between the image analysis test results, colorimeter readings, and laboratory test results.
Description
Keywords
Colorimeter device, Construction materials, Image analysis, Reclaimed asphalt pavement, Digital image, Moisture damage