It is anticipated that in FYs 2017-21, the Indiana Department of Transportation (INDOT) will perform 1500 lane miles of chip seal work each year. To ensure successful chip seals, INDOT has implemented visual inspection quality assurance (QA) procedures. However, concerns, such as reliability and validity of visual inspection, time and labor, and safety, have been raised on the current QA procedures. In response, this study aimed at developing novel concepts and providing innovative solutions to enhance the current QA practices over chip seal jobs.

The mean profile depth (MPD) was selected as the macrotexture metric to measure the quality of chip seal by considering the performance measures for pavement construction. Extensive testing was conducted to validate the use of this macrotexture metric to provide a cost-effective solution to assuring the quality of chip seal construction. The setup of texture testing system was evaluated and verified on both test tracks and actual chip seal projects. A field test protocol was developed to implement QA for chip seal.

It was found that use of at least two point lasers, one for each wheel path, is needed and anticipated to acquire the necessary information for evaluating the characteristics of texture profiles and capturing the spots of bleeding or tracking in both wheel paths. Texture measurements in one direction can provide sufficient information for the quality assurance of chip seal. Chip seal in the driving lane may experience higher variability than that in the passing lane. Therefore, the texture depths in the driving lane may yield more strict standards for quality assurance of chip seal. The current two QA inspections performed after one month and 12 months of service, respectively, can be combined into a single, one-time QA inspection that should be conducted after the first snow season and can ensure both road safety and chip seal quality.

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chip seal, seal coat, quality assurance, quality rating, surface friction, surface texture, macro-texture metrics, mean profile depth (MPD), point texture laser

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Performing Organization

Joint Transportation Research Program

Publisher Place

West Lafayette, Indiana

Date of this Version