Interface properties are typically measured using direct shear tests, such as the Leutner Test, performed on the interface between two pavement layers using a cored specimen taken from the road or manufactured in the laboratory. However, the measured properties cannot be considered to be a direct measure of the cohesive shear strength of the tack coat since the results tend to be affected by other factors such as aggregate interlock. A new test method has been developed to directly measure the cohesive properties of tack coats. A cylindrical asphalt mixture specimen (150 mm diameter and 100 mm thickness) is sawn horizontally to produce two cylindrical specimens. The cut faces are bonded together using the tack coat and the specimen is tested in the Leutner Test. The effects of test temperature, film thickness and curing period on the cohesive shear strength were determined. The cohesive shear strengths of a range of unmodified and polymer modified tack coats were also measured and compared. The method was found to provide consistent results over a range of testing conditions and tack coat types. The cohesive shear strength was found to decrease with increasing film thickness, testing temperature and increase with increasing curing time. (a) For the covering entry of this conference, please see ITRD abstract no. 0612AR242E.
Samenvatting