PRECISION OF MARSHALL STABILITY AND FLOW TEST USING 6-IN (152.4-MM) DIAMETER SPECIMENS

Earlier studies have shown that the repeatability of Marshall stabilit y, flow, and air voids content measurements on 6-in. (152.4-mm) diamet er specimens of large stone mixes is better than the repeatability on 4-in. (101.6-mm) diameter specimens. A round robin study involving twe lve participating laboratories was conducted to provide information fo r developing a precision statement for the ASTM Test Method for Resist ance to Plastic Flow of Bituminous Mixtures Using Marshall Apparatus ( 6 inch-Diameter Specimen) (D 5581). Difference two-sigma (d2s) limits were developed to determine acceptable single and multilaboratory diff erences for bulk specific gravity, percent voids, Marshall stability, and Marshall flow measurements. Analysis of other data collected durin g the study indicated that stability and flow measurements are not sen sitive to minor differences in various 6-in. (152.4-mm) diameter break ing heads currently in use.