Development of Loaded Wheel Test for Evaluating Bleeding in Chip Seals

Abstract

Bleeding is one of the most common distresses that leads to premature failure of chip seals. Bleeding reduces the surface texture of the pavement and thus compromises the safety of the traveling public, particularly during wet seasons and at intersections. Although factors that lead to premature bleeding are known, currently no laboratory test methods for evaluating bleeding in chip seals have been specified. The objective of this study was to develop a laboratory testing procedure and analysis framework for the evaluation of bleeding in chip seals by means of the loaded wheel test (LWT), specified in ASTM D6372. A new sample preparation, testing procedure, and analysis framework were proposed in this study to account better for the effects of existing pavement substrate, traffic load, traffic volume, and temperature. After samples were tested, bleeding was assessed on the basis of the percentage of asphalt at the surface of the seal; this percentage was determined with image processing analysis software (IPAS2) and surface texture measurements based on the sand patch method specified in the ASTM E965 standard procedure. Results indicated that the modified LWT method could quantify bleeding potential and bleeding development of laboratory prepared chip seal samples. Experimental factors including temperature, number of loading cycles, and contact stress were found to influence bleeding. Results showed that a moderate relationship existed between texture loss and the percentage of bleeding as measured by the IPAS2. Limited field validation results showed that texture loss could be an indicator of bleeding resistance.