Variability of Laboratory Relative Density Test Results
SourceFourteen Bureau of Reclamation soils laboratories conducted duplicate minimum, and wet and dry method maximum density tests on a fine and a medium sand. Data were analyzed on the basis of variations between laboratories and between duplicate tests. Results indicated that: (1) variations between laboratories were two to three times greater than variations between duplicate tests; (2) variations between laboratories for minimum and maximum densities were the same, or less than, variations reported for impact-type compaction tests; and (3) expressing the degree of compaction in terms of relative density, as compared to percent of maximum density, requires using different standards for both the level of compaction required and the limits within which compaction would be considered acceptable. Gradation tests on the two sands were also conducted by 16 laboratories and analyzed in the same manner.