New Brunswick Field Study on Optimization of Tack Coat Rate to Enhance Interface Bonding of Asphalt Layers

Tack coats are thin applications of emulsified asphalt used to create an adhesive bond between asphalt layers, to allow for creation of a monolithic structure as per pavement design requirements. The result is a “non-slip” or fully-bonded pavement layers to distribute the traffic loads in an acceptable stress level to the subgrade. However, fully-bonded conditions may not necessarily be achieved during the pavement construction if the application rates are not optimized. This paper presents results of a field study conducted on a four-lane highway in the province of New Brunswick. For this study, the maximum bond strength was determined by considering four tack coat spray rates in combination with two surface textures: milled surface and new asphalt mix. A section with no tack coat was also evaluated as a control section. Cores were subsequently collected following construction operations in order to evaluate the initial interlayer shear bond strength. An innovative “non-tracking” emulsion was used for this study as a tack coat for all the sections. Findings from this project will be used to provide recommendations and guidelines for optimum application rate, as well as construction best practices. This paper provides a summary of the field experiment and observations.


Varamini, S., Cormier, A., Sweezie, M., Barclay, R., Kucharek, A.S.

Titre de la séance

Testing and Modelling of Road and Embankment Materials (S)


Comité permanent des sols et des matériaux


Sols & matériaux
Conception et gestion ouvrages d’art







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