Modeling HMA Bulk Specific Gravities: A Theoretical and Experimental Investigation

Abstract

Bulk specific gravity, Gmb is of outstanding importance in bituminous mixes. Life cycle costs, contract requirements, and Quality Control/Quality Assurance procedures are strongly dependent on the effective Gmb and compliance with a number of boundary conditions. There are many ways to estimate Gmb and within-method variance is appreciable. The ”transportability” of a Gmb determined according to a given standard to another standard is therefore a critical issue. Our objective was to study relationships between Gmb values determined using a given standard to Gmb estimates calculated by applying other standards. We derived a model, and conducted experiments using five different methods. The model evaluates the elementary volumes that contribute to differences among the five considered method s. A tendency toward a common maximum value is assumed. The results are analyzed and interpreted, and the conceptual framework validated. Useful relationships between specific gravities determined by different methods are derived and analyzed. Power-asymptotic curve analysis yielded an algorithm well-grounded in logic to solve the issue of Gmb transportability.