A Review of Aggregate and Asphalt Mixture Specific Gravity ...

TABLE 15 Advantages and Disadvantages of Alternative Methods for G mbMethodAASHTO&/or ASTM AdvantagesDisadvantagesDesignationParaffin Coating T 275 Inexpensive Sample is un-useable aftertest Time consuming Operator dependent Wax penetrates large voids Potential safety issue withhandling of hot wax Difficult to coat specimenswith large aggregateParafilm D1188 Inexpensive Time consuming Operator dependent Very poor precision Film tears easily with largeaggregate size specimens Some bridging of surfacevoidsVacuum Sealing T 331 Solves problem with Equipment and bag costD6752 specimens havinginterconnected voids Slightly less precisecompared to T 166 Method has beenthoroughly evaluated Some bridging of surfacevoidsvs. other test methodsGammaRadiationnone Simple Limited research available atthis time(Troxler ) Equipment cost Poor precision Requires calibrationDimensionalmeasurementRapid WaterDisplacement(Gilson SG-4)T 269,paragraph 6.2 Simple Works only with specimenswith perfect shapes Under-estimates G mb sincesurface texture voids areincluded in volumenone Result in less than 2minutesNo standard methodavailable at this timeNo research available at thistimeMeasures apparent specificgravity21