Volume 7, Issue 1 (January 1979)
A Modified Procedure for Measuring the Maximum Specific Gravity of Bituminous Paving Mixtures
An accurate measurement of the maximum specific gravity of bituminous paving mixtures Gmm is needed for a reliable air voids analysis of the mixtures in the design and control phases. Since most actual bituminous mixtures combine absorptive aggregates, some difficulties have been encountered with the use of some current procedures for measuring Gmm. This paper presents a procedure for measuring the maximum specific gravity with the use of methanol. The good wetting ability of the methanol, together with its insignificant dissolvent characteristic, enables it to be used as a volumetric liquid for realistic measurements of Gmm. These properties eliminate the difficulties in expelling the trapped air bubbles even without vacuum as well as ensure almost no asphalt dissolution and thus no penetration of liquid inside the aggregate surface voids that are impermeable to asphalt. In general, the test was found to be fast and simple, with highly repeatable results.