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

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47was acceptable for both Marshall and Superpave mix designs at both medium and heavy trafficlevels.Asphalt contents were calculated for these mixtures using Equations 2.12 to 2.16. The asphaltcontent estimates calculated from these equations were consistently too high. Usingexperience gained after completing a few mix evaluations achieved better estimates than wereproduced with the equations.5.1.3 Specimen Fabrication and TestingAs prescribed under Marshall mix design, test specimens were prepared over a range ofdifferent asphalt percentages to determine the optimum asphalt content. This range consists of½ percent increments with two asphalt contents above and two below the estimated asphaltcontent. Also duplicate samples of each asphalt content were made. Two maximum specificgravity, or Rice, samples were also required at the estimated asphalt content according toAASHTO T209, making the total number of samples needed, 12 per mix design. Maximumspecific gravity test samples were not needed for all asphalt contents since the Marshall methodallows for estimation of the maximum specific gravity of the other asphalt contents from theone measured value. Equations 2.1 to 2.10 are used for this analysis.Once the aggregates for the mixtures had been combined for correct weight, they were heatedto the mixing temperature of 162 C. A sufficient amount of PG 64-22 asphalt binder was alsoheated to this temperature shortly before the mixing process. The mixing bowl and mixingwand were also heated to the compaction temperature. Mixing temperature was indicated inthe binder evaluation data from the Citgo Asphalt Data Sheet. This evaluation sheet alsoindicated that the compaction temperature was 149 C. In a separate oven, the compactionmolds were heated to the compaction temperature and the Marshall hammer was placed on ahotplate.The heated aggregate mixture was then placed into the mixing bowl and the required amount ofasphalt binder was added. This was immediately placed in the tabletop mixer and mixed untilthe aggregate and binder was thoroughly mixed. After mixing, the entire specimen was placedin the mold, spaded 25 times with a spatula, and placed on the compaction pedestal. Theretaining ring was placed over the mold, the compaction hammer placed in the mold andattached to the automatic lifting device. The lifting device was then activated to apply theapplicable number of blows to the specimen. The correct number of blows per side for Marshallmedium and heavy mixtures is 50 and 75, respectively. After the compaction to one side of thespecimen was complete, the mold was then flipped over and the compaction process repeatedfor the same amount of blows. Once the compaction process was complete, the sample andmold were removed and placed into the specimen extraction device. The specimen wasremoved from the mold and allowed to cool. This entire process was repeated for the tenspecimens used for determining the optimum asphalt content.
48Maximum specific gravity is a required value for determining the percent air voids of compactedsamples of that same mixture. Mixing samples for the maximum specific gravity is similar tomaking the Marshall samples. AASHTO T 209-94 was followed to determine the maximumspecific gravity.After test specimens were compacted, the bulk specific gravity and stability and flow weremeasured following AASHTO T 166-00 and T 245-97, respectively. The analog plots of loadversus time were used to determine the stability and flow for each sample.5.1.4 Mix Design Results and SummaryAfter the samples were mixed, compacted and tested the volumetric analysis was performed asreviewed in Chapter 2. An Excel spreadsheet was developed to compile and analyze the data.For the Marshall mix design the volumetric parameters are VMA, VFA and VTM. These resultswere graphed according to the Marshall mix design method.Other values such as stability and flow were acquired from the Marshall Testing Machine graphsand input into the spreadsheet. The Excel program also calculated the stability correction forheight after the measured height of each sample was input. Full-page printouts and designgraphs for each mix design are presented in the Appendix C.Table 5.2 contains the volumetric summary for the Marshall mix designs. WVDOH requiredvalues for properties listed are found in Table 2.2. As mentioned before the VMA for the two100% LS designs are right at the WVDOH minimum value. By adjusting the gradation curve awayfrom the maximum density line the VMA natural sand mixtures is 16.1%. VFA values are allwithin WVDOH specifications, although they are all toward the upper limit of the requirement.The 13% natural sand Medium design had a stability of 8075 lb., which is close to the minimumcriteria of 8000 lb. All other mixes had stability values well above the minimum requirement.As expected, the stability values decreased in the medium design of each mixture type and alsodecreased with the addition of natural sand content. Conversely, flow values did the opposite,increasing in the medium level mixture and with increased sand content.Table 5.2 Marshall Mix Design Volumetric SummaryMix TypeAsphalt(percent)VMA(percent)VFA(percent)Stability(N)Flow(mm)MR HVY 100% LS 5.2 15.0 74.0 10231 13.9MR MED 100% LS 5.5 15.1 72.5 9341 14.9MR HVY 13% NS 5.9 16.1 75.0 9450 11.3MR MED 13% NS 6.0 16.1 75.5 8075 16.0
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: Percent Passing4610090100% Limeston
Page 59 and 60: 50gradation. This allowed for direc
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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