Laboratory Evaluation of Microsurfacing Bond Strength

Abstract

This paper summarizes the results of a study that was conducted to evaluate the influence of different factors on the bond strength between a microsurfacing layer and an existing pavement structure. The considered factors included the tack coat residual application rate and the dilution rate, as well as the residual binder content of microsurfacing mix. To this end, five tack coat residual application rates, two dilution rates, and three different residual binder contents of the microsurfacing mix were evaluated. A new method for preparing and testing samples was developed to measure the microsurfacing mix bond strength using pull-off and torque tests. The results of this study indicated that the microsurfacing samples with tack coat had significantly higher interlayer bond strength values than those without tack coat. The use of a high dilution rate resulted in an excess amount of water, which significantly reduced the interlayer bond strength. The results also indicated that the amount of residual binder content in the microsurfacing mix significantly affected their bond strength with the existing pavement. Thus, the results of this paper indicate that the bonding between the microsurfacing layer and the existing pavement layer is a function of the properties of the microsurfacing mix and the applied tack coat material.