Development of aggregate gradation based on asphalt film thickness and aggregate structure

Abstract

This study is an attempt to make the aggregate blending methodology, used during the mix design process of asphalt mixture, independent of control points. The proposed procedure involves optimization of aggregate gradation based on the concept of apparent asphalt film thickness (AAFT) and balance within the aggregate structure. The underlying hypothesis was validated by comparing the volumetrics and performance of asphalt mixtures, prepared using two generated aggregate gradations, with a control asphalt mixture. The results indicated that the generated aggregate gradations had similar rutting, fatigue, and moisture sensitivity properties to the control mix. Three field trial sections were laid using the proposed procedure. Preliminary investigation revealed comparable to better density and Marshall characteristics than the conventional mixture. It is envisaged that the results and discussions from the present study can be used with the approach of balanced mix design for choosing an aggregate gradation with desirable performance attributes.