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

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495.2 SUPERPAVE MIX DESIGNSAs with the Marshall mixes, the Superpave mixes were designed to be applicable to localconditions. The same aggregate stockpiles and asphalt cement were used for both mix types.The Superpave mix design procedure allows for more traffic levels than the Marshall procedure.The research plan called for developing Superpave mix designs comparable to the Marshalldesigns. In addition, a 100% crushed limestone mix and a mix with the maximum amount ofnatural sand was developed for the light traffic level. Since the consensus aggregaterequirements are significantly relaxed for light traffic volume roads, it was possible to developmix designs with high natural sand contents.The dust to binder ratio controls the amount of dust is used in a Superpave mixture. This ratioaffects the gradation limits for Pan material specified by Superpave as 2.0 to 10.0 percent.However, the dust to binder ratio effectively limits this range as a function of the percenteffective binder. For example, if the effective binder content is 5 percent, the amount ofmaterial passing the #200 sieve must be in the range of 3.0 to 6.0 percent for the mix to meetthe D/B criteria. Thus, the D/B criterion is a limiting factor on the number of acceptablemixtures which can be made with available aggregate stockpiles. The Superpave low trafficmixtures which were designed to be above the restricted zone were directly affected by the D/Bratio. In all cases, the D/B criteria limited the range of material passing the #200 sieve to lessthat the aggregate specification limits. Hence, if the D/B criterion is enforced, essentiallycontrols this portion of the aggregate blend.5.2.1 Types of Mixes DevelopedEight Superpave mixes were designed for this project. The blends of stockpile materials areshown in Table 5.3. Four of these mixes mimic the Marshall mixes, two 100% limestonemixtures and two 13% natural sand mixes at traffic levels of medium and high. The two mixescontaining 13% natural sand contain the exact same blends and gradations as the comparableMarshall mixes. The blends gradations for the heavy and medium traffic Superpave mixes with100% limestone were adjusted to better meet the Superpave criteria. Four Superpave lighttraffic designs were developed. One contained the maximum amount of natural sand that couldbe used while meeting the Superpave consensus aggregate specifications. One containedapproximately half this amount of sand, but the exact proportion was determined during themix design process. Two light traffic mixes were designed with 100% limestone. One was thefinest mix that could be developed based on the stockpile gradations. One was prepared withthe same gradation as the mixes with natural sand. These were designed above the restrictedzone and two contained large amounts of natural sand. Of the two remaining mixes onecontained 100% limestone but was passed through the restricted zone due to major difficultiesin combining the research stockpiles into a 100% limestone mixture above the restricted zone.The final mixture is one that mimics the 100% natural sand mixture. This was accomplished byaltering the gradation of the limestone sand stockpile to match that of the natural sand
50gradation. This allowed for direct comparison of a natural and limestone sand mix with thesame proportions of sand.Table 5.3 Blend Percentages for Superpave MixturesStockpile TypesDesignation Traffic Level Skid N.Sand L.Sand #9 BH FinesSP HVY 13%NS Hvy 13% N. Sand 20 13 28 38 1SP MED 13%NS Med 13% N. Sand 20 13 28 38 1SP HVY 100%LS Hvy 100% L. Sand 15 0 45 39 1SP MED 100%LS Med 100% L. Sand 15 0 45 39 1SP LGT 100%LS Lgt 100% L. Sand 15 0 78 7 0SP LGT 40%NS Lgt 40% N. Sand 15 39.6 40 3 2.4SP LGT 64%NS Lgt 64% N. Sand 32 64 0 0 4SP LGT 100%LS Lgt 100% LS mod 32 0 64 0 4A search for existing Superpave mix designs in use by companies across the state found no mixesof interest for this project so all Superpave mixes used were developed in the laboratory.5.2.2 Determining the Design Aggregate StructureAggregates used for the Superpave portion of the research were the same as used during theMarshall tests, meaning the aggregate was sieved, washed and dried in the same way. Also, thesame Excel spreadsheet, with modifications to better match Superpave design, was utilized toaid in developing the aggregate mixtures and gradation curves. The stockpile percentages andgradation curves for all Superpave mixtures can be seen in Table 5.3 and Figures 5.2 and 5.3.The asphalt contents for all the Superpave mixtures were estimated using Equations 2.12 to2.16. The estimated asphalt contents were consistently higher than the optimum percentbinder determined from the mix design procedure. However, the estimates were a reasonablestarting point for mix design.
Page 1 and 2:
COMPARISON OF 9.5 MM SUPERPAVE ANDM
Page 3 and 4:
iNOTICEThe contents of this report
Page 5 and 6:
iiiasphalt concrete wearing courses
Page 7 and 8: vMixing Procedure 78Appendix B Fine
Page 9 and 10: viiTable C-7 Marshall Medium 13% NS
Page 13 and 14: 4Table 1.1 Mix Design Types in Expe
Page 15 and 16: 6CHAPTER 2 LITERATURE REVIEW2.1 INT
Page 17 and 18: 82. determine aggregate stockpile b
Page 19 and 20: 10SieveAllowable PercentPassing Sie
Page 21 and 22: 12Stability is recorded as the maxi
Page 23 and 24: 14The WVDOH procedure for determini
Page 25 and 26: 16sieve. This is somewhat different
Page 27 and 28: 18G sb = bulk specific gravity of a
Page 29 and 30: 20theoretical gravity at the initia
Page 31 and 32: 22D/B est = adjusted dust to binder
Page 33 and 34: 24P b,est - 0.5%,P b,est ,P b,est +
Page 35 and 36: Percent Passing261009080Superpave U
Page 37 and 38: 28Table 2.6 WVDOH Marshall and Supe
Page 39 and 40: 30Table 2.9 Habib Marshall Analysis
Page 41 and 42: 32theoretically correct in that the
Page 43 and 44: 34the machine. This variability was
Page 45 and 46: 36CHAPTER 3 EQUIPMENT3.1 INTRODUCTI
Page 47 and 48: 38Hose PressureWheel Load100 psi100
Page 49 and 50: 40mouth. This jar rests on a holder
Page 51 and 52: problematic, as the saturated surfa
Page 53 and 54: 44Mechanical Laboratory Sieve. Afte
Page 55 and 56: Percent Passing4610090100% Limeston
Page 57: 48Maximum specific gravity is a req
Page 61 and 62: Percent Passing521009080Light 100%
Page 63 and 64: 54percentage of aggregate from the
Page 65 and 66: 56Table 5.4 Summary of Volumetric a
Page 67 and 68: 58Table 5.5 Calculated and Adjusted
Page 69 and 70: 60Table 5.6 Results of APA TestsAir
Page 71 and 72: 62exhibit lower rut depths than any
Page 73 and 74: design had significantly more rutti
Page 75 and 76: 66SP L 100LS SP L 64NS -10.335 2.77
Page 77 and 78: 68percent air voids and percent lim
Page 79 and 80: Air Voids (%)Uncompacted Voids (%)7
Page 81 and 82: 72than the Marshall mixes. Table 6.
Page 83 and 84: Voids in the Mineral Aggregate. As
Page 85 and 86: 76REFERENCESAmerican Association of
Page 87 and 88: 78APPENDIX A BUCKET MIXER INSTRUCTI
Page 89 and 90: 80APPENDIX B FINE AGGREGATE ANGULAR
Page 91 and 92: 82Table B-3 Uncompacted Void Conten
Page 93 and 94: 84AGGREGATE DESIGN DATATable C-1 St
Page 95 and 96: 86Table C-3 Computed Blend Gradatio
Page 97 and 98: 88Table C-7 Marshall Medium 13% NS
Page 99 and 100: 90%G mm%AC VMA VTM VFA @ N ini @N d
Page 101 and 102: 92Table C-14 Superpave Light 64% NS
Page 103: 946 2979.3 1696.7 2988.1 2.307 7.09
Page 106 and 107: 971 2912.7 1620.8 2917.9 2.246 7.65
Page 108 and 109:
992 8.40 10.80 7.402 7.90 9.90 7.80
Page 110 and 111:
1011 9.50 6.90 11.502 9.79 7.15 10.
Page 112 and 113:
1032 8.55 5.20 5.95L R RDate Tested
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