Comparison of 9.5 mm SuperPave and Marshall Wearing I Mixes in ...

41F = net mass, g, of fine aggregate in measure,G sb = bulk dry specific gravity of fine aggregate,4.4 FAA TEST RESULTSTests were run on the six combinations of limestone and natural sands. The experimental dataare presented in Appendix B. Results for each combination were analyzed and are displayed inTable 4.1. Column 3 shows the results for obtained by testing the blended sands. Column 4shows the results obtained by computing the blended FAA based on the FAA of the limestoneand the natural sand and using Equation 2.11. The 100% LS sand had a FAA of 43.5 percent.This is less than the minimum requirement Superpave heavy traffic designs, which requires anuncompacted voids of 45%. Thus, none of the blends meet the requirements for high volumeroads. However, all the blends meet the requirements for other traffic levels.Table 4.1 Results of Fine Aggregate Angularity Tests.Mix TypeSpecific GravityTest ResultsUncompacted Voids(percent)Computed ResultsUncompacted Voids(percent)100% LS 2.618 43.5 -75% LS - 25% NS 2.596 42.5 42.568% LS - 32% NS 2.591 41.6 42.250% LS - 50% NS 2.575 41.2 41.525% LS - 75% NS 2.554 40.2 40.4100% NS 2.534 39.4 -Comparison of the test results from the blended material and the computed results shows onlyminor differences. However, in three of four cases, the computed values were higher than themeasured values.4.5 CONCLUSIONThe FAA test is fairly simple and can be performed rapidly once the specific gravity of the sand isknown. The results obtained were consistent with the expectations. The FAA value for thecrushed limestone sand was 43.5 percent. This is less than the required specification for hightraffic volume Superpave mixes. However, the supplier of these aggregates routinely uses themfor Superpave mixes. As shown in Equation 4.1, the uncompacted void content is sensitive tothe bulk specific gravity. Determining the bulk specific gravity of crushed limestone sand is