The performance of an asphalt mixture overlay depends on the interface bond strength between the newly constructed asphalt mixture lift and the underlying pavement layers. TRB hosted a webinar on Wednesday, March 31, 2021 from 2:00-3:30 PM Eastern that discussed the use of tack coat materials in asphalt pavements. A tack coat typically consists of emulsified asphalt, and is commonly used to achieve the necessary bonding between pavement layers. Tack coats can also ensure pavement layers behave as a monolithic system that withstands traffic and environmental stresses. Presenters identified several factors that may affect bond performance, including tack coat material type, tack coat application rate, pavement surface type, temperature, and construction site conditions. They also discussed test development, laboratory evaluation, and field validation of various tack coat materials.

This webinar is sponsored by the TRB Standing Committee on Asphalt Mixture Evaluation and Performance. It also features research from NCHRP Research Report 712: Optimization of Tack Coat for HMA Replacement and NCHRP Report 878: Validation of the Louisiana Interlayer Shear Strength Test for Tack Coat.

The slides and recording are available.

Webinar agenda and presenters

1. Effect of tack coat materials on durability of asphalt pavement: Louay Mohammad, Louisiana State University
2. Tack coat performance in cold regions: Laura Stasiuk, University of Saskatchewan
3. Tack coats for micro-surfacing applications: Mounir Nazzal, University of Cincinnati
4. Question and answer session: Danny Gierhart, Asphalt Institute

The first 60 minutes of the webinar will be for presentations and the final 30 minutes will be reserved for audience questions.

Learning Objectives

At the end of this webinar, participants will be able to:

1. Discuss appropriate selection of tack coat materials and application rates
2. Develop specifications for the use of tack coat materials

Professional Development Hours

Professional Development Hours (PDHs) earned on completion of this program were reported to the Registered Continuing Education Program (RCEP). Certificates of Completion are issued to all participants via the RCEP.net online system. Complaints about registered providers may be addressed to RCEP, 1015 15th Street, NW, 8th Fl., Washington, DC, 20005.