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

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37sample are then placed into the compression device. The compression device loads the sampleat a deformation rate of two inches per minute. A load cell is activated and sends a signal to thex-y plotter that records a load-deformation curve for the sample. The stability and flow of thesample are determined from this graph.To verify the calibration of the Marshall Testing Machine, a proving spring provided by themanufacturer is placed in the testing machine, and with a calibration paper in the x-y. Theproving spring is then loaded. If the graphed line stays within two parallel lines pre-printed onthe calibration paper, then the machine’s calibration is verified. Calibration was verified severaltimes throughout the development of the Marshall mix designs and the machine was alwayswithin tolerance.3.4 SUPERPAVE GYRATORY COMPACTORThe Superpave Gyratory Compactor is a relatively new device for use in the compaction ofasphalt pavement specimens. This compactor was developed during the Strategic HighwayResearch Program, SHRP. The gyratory compactor uses a shearing action to compact thespecimens. This is accomplished by constant tilting of the mold about a load head. The mold isheld at a slight angle to achieve the shearing action. This method of compaction was found tobest simulate in-field compaction practices due to its ability to correctly orient the aggregates inthe mix. (Roberts, 1996)The Superpave gyratory compactor used during this research was a Pine Instruments AFGC125XGyratory Compactor. This apparatus is self-contained and fully automated. The operatorensures that the compactor is set to the correct compaction mode or number of gyrations.Then the mold containing a specimen is placed into the compaction chamber and the startbutton pressed. Once compaction is complete, and the load ram is returned to the rest position,the mold is removed and placed over the extracting device until the sample is cool enough forextraction.Calibration of the gyratory compactor is a complicated procedure and is only required onceevery year. However, a simple verification procedure is performed to confirm the machine iscalibrated. Verification should be performed every six months under normal operation. Thecalibration and verification processes ensure the compactor is within the tolerances set by boththe manufacturer and the Superpave mix design method. Verification and calibration arerequired for the speed of gyration, ram force, ram position and angle of gyration.3.5 ASPHALT PAVEMENT ANALYZERThe Asphalt Pavement Analyzer, APA, was used to evaluate the potential performance of themixes with respect to rutting. All samples were prepared to a 7 0.5% void content. Thefollowing operational parameters were used for all tests:Temperature40 C
38Hose PressureWheel Load100 psi100 lbsThe only calibration that is needed for the APA is that of the load placed on the samples by therollers. This is accomplished by placing a load cell under one of the rollers and adjusting thepressure displayed on the APA gauges with the pressure reading from the load cell. This is to bedone with each of the three rollers.3.6 BUCKET MIXER DESCRIPTION AND USEDue to the large amount of asphalt pavement samples needed and the fact that most of thosewere Superpave samples, a large Kol Brand bucket mixer was used. This mixer was used toprepare all Superpave samples. The bucket mixer has a ½ horsepower motor that rotates thefive-gallon mixing bucket at a rate of 60 RPM. The bucket can be tilted from its vertical positionto a plane parallel with the floor. A mixing paddle placed into the bucket and secured by asupport rod ensures agitation of the mix.Hughes performed an extensive study into the use of the bucket mixer (Hughes, 1999). Hispaper outlines procedures for correctly using the mixer, allowable capacities and mixingtechniques. It was found that the bucket mixer could properly mix asphalt mix samples rangingin size from 1200g to 18,000g. It was also determined that there may be problems with mixinglarge samples of low asphalt content, but no problem was encountered during any mixing forthis research. The mixing procedure developed by Hughes was followed during this research.This process is described in Appendix A.
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: 36CHAPTER 3 EQUIPMENT3.1 INTRODUCTI
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 and 58: 48Maximum specific gravity is a req
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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