Tack Coat Rheological Properties and the Effects on Interlayer Shear Strength

Abstract

CSS-1H emulsions are the most commonly used slow-setting grades in Oregon. New engineered emulsions have recently been developed in Oregon to reduce tracking and increase interlayer shear strength (ISS). In this study, the performance of these emulsions, most effective application rates, and the effects of pavement surface texture and traffic/environment on ISS are evaluated. Results indicate that there are positive correlations between rheological tests and ISS from field cores, which generate a linear equation that can predict in situ ISS using the results of simple rheological experiments. Results show variances in application rates and uniformity by distributor trucks. Hence there is a need for unified guidelines on tack coat quality control and quality assurance (QC/QA) and construction practices.