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35 Table 26. Test recommendations and proposed specification limits. Recommended Proposed Specification for Specification Traffic Test Use (ESAL) Limit Less Than 40%, Minimum Uncompacted Void Content of Coarse 100,000 Yes Aggregate, Method A (AASHTO TP56)1 100,000 45%, Minimum and above Flat or Elongated Particles in Coarse Yes All 50%, Maximum Aggregate (ASTM D4791) Less Than 40%, Minimum Uncompacted Void Content of Fine 500,000 Yes Aggregate, Method A (ASTM C1252)2 500,000 45%, Minimum and above Methylene Blue Test for Fine Aggregate No -- -- (AASHTO TP57) Methylene Blue Test for p0.075 Material No -- -- (AASHTO TP57) Particle Size Analysis of p0.075 Materials No -- -- for Determining D60, D30, and D10 Sizes Micro-Deval Test (AASHTO TP58) Yes All 15%, Maximum Magnesium Sulfate Soundness Test Yes All 20%, Maximum (AASHTO T104) 1 Same recommendation and proposed specification applies to Method B as well. 2 Same recommendation and proposed specification applies to Method B and Virginia Test Method for Determining Percent Voids in Fine Aggregate (VTM5) as well. practice to include both tests when specifying coarse aggre- descriptive rankings than the UVA results. As a result, the fol- gates for use in HMA. If the coarse aggregate UVA test is used lowing discussion of fine aggregate UVA applies to both fine alone, aggregates with very high FOE21 values could be used aggregate UVB and VTM5 methods. It seems appropriate to because they would also have high UVA values. Aggregates recommend that any of the three tests can be used for speci- with extremely high FOE21 values could cause problems in fication purposes for fine aggregates used in HMA mixtures; HMA mixtures. the choice can be left to the specifying agency. Most coarse aggregates used in this research have FOE21 Similar to the coarse aggregate, the relationship between traf- values between 35 and 50 percent. The FOE21 value of 50 fic and fine aggregate UVA appears to be less sensitive at lower percent appears to be a reasonable upper limit for specifica- traffic levels than at higher levels. In the case of fine aggregate tion purposes. UVA, the value of approximately 45 percent seems to be a logi- cal break point. HMA performance is markedly improved with fine aggregate UVA values above 45 percent compared to HMA Fatigue with fine aggregate UVA values below 45 percent. Using the APT The research shows that as FOE21 increases, HMA mix- equivalency factor of 2,500 ESAL per pass, it might be appro- ture resistance to fatigue cracking increases. It should be priate to allow the use of fine aggregate UVA as low as 40 per- recognized that this trend is based on only three data points cent for traffic levels below 500,000 ESAL and 45 percent or and that many other factors contribute to the fatigue per- higher for traffic levels of 500,000 ESAL or higher. formance of an HMA mixture. Nevertheless, there is no log- The results of APT moisture susceptibility tests indicate ical reason to discard the FOE21 test as an aggregate test that, in the presence of moisture, fine aggregate UVA is a bet- related to fatigue performance. ter predictor of rutting performance than any other test; rutting decreases with increasing fine aggregate UVA. The sensitivity discussion previously applied to dry APT testing Fine Aggregate Uncompacted Void appears to be true of tests in the presence of moisture as well. Content Rutting Fatigue Rutting performance of fine-graded HMA mixtures is related to fine aggregate UVA. The HMA mixture rutting Data indicate a relationship between HMA mixture fatigue resistance increases with increasing fine aggregate UVA. Both performance and fine aggregate UVA might exist. As the fine fine aggregate UVB and VTM5 test results have slightly higher aggregate UVA increases, HMA mixture fatigue cracking