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Using a single test to determine specific gravity and absorption of aggregate blends Hall, Kevin D

By: Publication details: Transportation Research Record, 2004Description: nr 1874, s. 3-10Subject(s): Bibl.nr: VTI P8167:1874; VTI P8169:2004Location: Abstract: The ability to measure the specific gravity of an aggregate accurately and consistently is paramount to transportation materials engineers. Current standard test methods (AASHTO T-84 and T-85) typically are not used for routine quality control purposes because of long testing times and questions about variability. Among new techniques developed for measuring specific gravity and absorption is a vacuum-sealing method, which eliminates the need for long soaking periods and for determining aggregate mass in a saturated-surface-dry moisture state. The vacuum-sealing method also has the potential to measure the specific gravity of a blend of aggregates in a single test. Specific gravity and absorption of six coarse and four fine aggregates composed of various mineralogy types were measured by both traditional and vacuum-seal methods. Ten blends, whose gradations generally met Superpave hot-mix asphalt specifications, were created by using various combinations of aggregates and tested in a single vacuum-seal test. Five replicate tests were done on all individual aggregates and blends. Aggregate-blend single-test results (specific gravity and absorption) were compared with values obtained with traditional individual test results and mathematical combinations. The comparisons yielded generally strong correlations among methods, indicating the vacuum-seal procedure has promise as a relatively rapid method for determining specific gravity and absorption in a single test of an aggregate blend. However, some real differences in test values suggest that the vacuum-seal method needs refinement before it can be seamlessly substituted for traditional methods.
Item type: Reports, conferences, monographs
Holdings
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Statens väg- och transportforskningsinstitut Available
Statens väg- och transportforskningsinstitut Available

The ability to measure the specific gravity of an aggregate accurately and consistently is paramount to transportation materials engineers. Current standard test methods (AASHTO T-84 and T-85) typically are not used for routine quality control purposes because of long testing times and questions about variability. Among new techniques developed for measuring specific gravity and absorption is a vacuum-sealing method, which eliminates the need for long soaking periods and for determining aggregate mass in a saturated-surface-dry moisture state. The vacuum-sealing method also has the potential to measure the specific gravity of a blend of aggregates in a single test. Specific gravity and absorption of six coarse and four fine aggregates composed of various mineralogy types were measured by both traditional and vacuum-seal methods. Ten blends, whose gradations generally met Superpave hot-mix asphalt specifications, were created by using various combinations of aggregates and tested in a single vacuum-seal test. Five replicate tests were done on all individual aggregates and blends. Aggregate-blend single-test results (specific gravity and absorption) were compared with values obtained with traditional individual test results and mathematical combinations. The comparisons yielded generally strong correlations among methods, indicating the vacuum-seal procedure has promise as a relatively rapid method for determining specific gravity and absorption in a single test of an aggregate blend. However, some real differences in test values suggest that the vacuum-seal method needs refinement before it can be seamlessly substituted for traditional methods.

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