Advanced Characterization of Clear Chip Seals

Chip seals are widely used throughout the world for the construction and preventive maintenance of asphalt pavements because they are recognized as cost-effective solutions able to improve skid resistance while creating a waterproof surface. On the other hand, chip seals are often affected by early stone loss because of several, not always easily manageable, material-related and traffic-related factors. It is, therefore, in the interest of researchers to develop scientific methods able to predict the aggregate retention performance of chip seals. Given this background, in the present paper, a performance-based evaluation of chip seals with regard to aggregate retention properties is carried out through a laboratory test based on the Ancona shear testing research and analysis equipment. In this study, a chip seal prepared with a clear emulsion derived by emulsifying a synthetic clear binder was analyzed and compared with two traditional chip seals manufactured with a plain cationic bituminous emulsion and a styrene butadiene styrene polymer-modified asphalt emulsion, respectively. Specifically, six chip seals obtained by combining the three selected emulsions with two types of aggregates (crushed limestone and basalt) were tested at three different temperatures. Moreover, a rheological characterization of emulsion residues was also carried out through the dynamic shear rheometer and the binder bond strength adhesion tester. Results mainly showed that the investigated clear synthetic emulsion can be successfully used for the construction of clear chip seals in combination with aggregates of different mineralogy.