Field Evaluation of Surface Friction Performance of Chip Seals in Indiana

Abstract

Chip seal has been widely used as an effective surface treatment for pavement preservation. The Indiana Department of Transportation (DOT) chip sealed a total of 373 lane mile pavements in 2008 and 700 lane mile pavements in 2009. However, many issues, such as the optimal use of local materials and new aggregates, remained unsolved. No original information was available at the time for Indiana DOT engineers to assess the performance of chip seal pavements. A research study was initiated by the Indiana DOT to evaluate the field performance of chip seal pavements, particularly the surface friction properties. Eighteen chip seal projects were selected as the test sections for this study. Field testing was conducted to measure pavement surface friction and texture properties. The true surface friction numbers were identified for chip seals after 12 months of service. The variation of surface friction on chip seals was analyzed. Factors affecting chip seal surface friction, such as aggregate, traffic volume, and existing pavement condition, were identified and examined. Three traffic levels were defined for better chip seal application. The international roughness index on the existing pavement affected chip seal friction performance. A criterion was recommended for assessing the friction performance of chip seal and identifying the possible failure of a chip seal.