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122 APPENDIX Proposed Standard Method of Test for Long-Term Conditioning of Hot Mix Asphalt (HMA) for Performance Testing
123 Standard Method of Test for LongâTermÂ ConditioningÂ ofÂ HotÂ MixÂ AsphaltÂ (HMA)Â forÂ PerformanceÂ TestingÂ AASHTO Designation: TP xxx-xx 1 SCOPEÂ 1.1 ThisÂ standardÂ practiceÂ describesÂ aÂ procedureÂ forÂ theÂ longâtermÂ conditioningÂ ofÂ uncompactedÂ hotÂ mixÂ asphaltÂ (HMA)Â forÂ performanceÂ testingÂ toÂ simulateÂ theÂ agingÂ thatÂ occursÂ overÂ theÂ serviceÂ lifeÂ ofÂ aÂ pavement.Â TheÂ procedureÂ forÂ longâtermÂ conditioningÂ inÂ performanceÂ testingÂ isÂ precededÂ byÂ aÂ procedureÂ forÂ shortâtermÂ conditioningÂ inÂ mixtureÂ mechanicalÂ propertyÂ testingÂ inÂ AASHTOÂ RÂ 30.Â 1.2 ThisÂ standardÂ mayÂ involveÂ hazardousÂ material,Â operations,Â andÂ equipment.Â ThisÂ standardÂ doesÂ notÂ purportÂ toÂ addressÂ allÂ safetyÂ problemsÂ associatedÂ withÂ itsÂ use.Â ItÂ isÂ theÂ responsibilityÂ ofÂ theÂ userÂ ofÂ thisÂ procedureÂ toÂ establishÂ appropriateÂ safetyÂ andÂ healthÂ practicesÂ andÂ toÂ determineÂ theÂ applicabilityÂ ofÂ regulatoryÂ limitationsÂ priorÂ toÂ use.Â 2 REFERENCEDÂ DOCUMENTSÂ 2.1 AASHTOÂ Standards:Â ï¼ PP 3, Preparing Hot Mix Asphalt (HMA) Specimens by Means of the Rolling Wheel Compactor ï¼ PP 60, Preparation of Cylindrical Performance Test Specimens Using the Superpave Gyratory Compactor (SGC) ï¼ R 30, Mixture Conditioning of Hot Mix Asphalt (HMA) ï¼ T 312, Preparing and Determining the Density of Hot Mix Asphalt (HMA) Specimens by Means of the Superpave Gyratory Compactor ï¼ T 316, Viscosity Determination of Asphalt Binder using Rotational Viscometer 2.2 OtherÂ Document:Â ï¼ Draft Final Report for NCHRP Report 9-54, Long-Term Aging of Asphalt Mixtures for Performance Testing and Prediction, October 1, 2017.
124 3 TERMINOLOGYÂ 3.1 Definitions:Â 3.1.1 EnhancedÂ IntegratedÂ ClimaticÂ ModelÂ (EICM)Â âÂ AÂ oneâdimensionalÂ coupledÂ heatÂ andÂ moistureÂ flowÂ modelÂ thatÂ canÂ beÂ usedÂ toÂ determineÂ pavementÂ temperatureÂ atÂ anyÂ depthÂ ofÂ interest.Â 4 SUMMARYÂ OFÂ PracticeÂ 4.1 AÂ mixtureÂ ofÂ binderÂ andÂ aggregateÂ isÂ conditionedÂ inÂ aÂ forcedâdraftÂ ovenÂ atÂ 95Â°CÂ afterÂ priorÂ shortâtermÂ conditioningÂ forÂ mixtureÂ mechanicalÂ propertyÂ testingÂ accordingÂ toÂ RÂ 30.Â TheÂ durationÂ ofÂ conditioningÂ atÂ 95Â°CÂ isÂ selectedÂ toÂ reflectÂ theÂ time,Â climate,Â andÂ pavementÂ depthÂ forÂ aÂ givenÂ pavementÂ locationÂ inÂ theÂ UnitedÂ StatesÂ usingÂ theÂ climaticÂ agingÂ indexÂ (CAI).Â TheÂ longâ termÂ conditionedÂ looseÂ mixtureÂ samplesÂ areÂ preparedÂ forÂ maximumÂ specificÂ gravityÂ (Gmm)Â testingÂ andÂ thenÂ compactedÂ forÂ subsequentÂ performanceÂ testing.Â 5 SIGNIFICANCEÂ ANDÂ USEÂ 5.1 TheÂ longâtermÂ performanceÂ ofÂ HMAÂ canÂ beÂ predictedÂ moreÂ accuratelyÂ byÂ usingÂ conditionedÂ testÂ samplesÂ ratherÂ thanÂ unconditionedÂ samples.Â TheÂ longâtermÂ mixtureÂ conditioningÂ inÂ theÂ performanceÂ testingÂ procedureÂ isÂ designedÂ toÂ simulateÂ theÂ agingÂ thatÂ theÂ mixtureÂ willÂ undergoÂ inÂ service.Â 6 APPARATUSÂ 6.1 Oven:Â AÂ forcedâdraftÂ oven,Â thermostaticallyâcontrolledÂ withÂ horizontalÂ airÂ flow,Â andÂ capableÂ ofÂ maintainingÂ anyÂ desiredÂ temperatureÂ settingÂ fromÂ roomÂ temperatureÂ toÂ 176Â°CÂ withinÂ Â±Â 3Â°C.Â 6.2 Thermometers:Â ThermometersÂ havingÂ aÂ rangeÂ fromÂ 50Â°CÂ toÂ 260Â°CÂ andÂ readableÂ toÂ 1Â°C.Â 6.3 Miscellaneous:Â AÂ metalÂ panÂ forÂ heatingÂ aggregate,Â aÂ shallowÂ metalÂ panÂ forÂ theÂ shortâtermÂ conditioningÂ ofÂ uncompactedÂ HMA,Â aÂ 1âinchÂ tallÂ metalÂ panÂ forÂ theÂ longâtermÂ conditioningÂ ofÂ uncompactedÂ HMA,Â aÂ metalÂ spatulaÂ orÂ spoon,Â timer,Â andÂ glovesÂ forÂ handlingÂ hotÂ equipment.Â
125 7 HAZARDSÂ 7.1 ThisÂ standardÂ involvesÂ theÂ handlingÂ ofÂ HMAÂ thatÂ canÂ causeÂ severeÂ burnsÂ ifÂ itÂ contactsÂ skin.Â FollowÂ safetyÂ precautionsÂ toÂ avoidÂ burns.Â Â 8 LONGâTERMÂ MIXTUREÂ CONDITIONINGÂ PROCEDUREÂ 8.1 TheÂ longâtermÂ conditioningÂ forÂ performanceÂ testingÂ appliesÂ toÂ laboratoryâ preparedÂ looseÂ mixturesÂ thatÂ haveÂ beenÂ subjectedÂ toÂ shortâtermÂ conditioningÂ asÂ partÂ ofÂ theÂ mixtureÂ mechanicalÂ propertyÂ testingÂ procedureÂ describedÂ inÂ RÂ 30.Â 8.2 DetermineÂ theÂ requiredÂ longâtermÂ conditioningÂ durationÂ thatÂ reflectsÂ theÂ desiredÂ fieldÂ agingÂ inÂ termsÂ ofÂ age,Â climate,Â andÂ depthÂ usingÂ EquationÂ 1.Â 1 exp( / ) / 24 N oven a i i t DA E RT ï½ ï½ ïï¥ (1) whereÂ toven = required oven aging duration at 95Â°C to reflect field aging (days); CAI = climatic aging index; D = depth correction factor; A = frequency (pre-exponential) factor; Ea = activation energy; R = universal gas constant, or ideal gas constant; Ti = pavement temperature obtained from the EICM at the depth of interest at the hour of interest, i (Kelvin); Â TableÂ 1Â listsÂ theÂ valuesÂ ofÂ D,Â A,Â andÂ Ea.Â Table 1 â Climatic Aging Index Fitting Coefficients Pavement Layer Depth CorrectionFactor (D) Pre-exponential Factor (A) Activation Energy (Ea) Surface Layer (6 mm) 1.0000 1.40962 13.3121 20-mm Depth 0.4565 1.40962 13.3121 Deeper Layers (below 20 mm) 0.2967 1.40962 13.3121 8.2.1 Break down any large chunks of asphalt mixtures in the short-term aged loose mixture sample, taking care to avoid fracturing the aggregate, so that the clusters of the fine aggregate portion are not larger than the nominal maximum aggregate size (NMAS). This step needs to be performed shortly after short-term aging to ensure that the asphalt mixture is sufficiently soft to be separated into pans for
126 oven aging. If an HMA sample is not sufficiently soft to be separated manually, then place it in a pan and warm it in an oven until it can be separated as described. 8.2.2 ApportionÂ theÂ shortâtermÂ agedÂ looseÂ mixtureÂ intoÂ severalÂ pansÂ suchÂ thatÂ eachÂ panÂ hasÂ aÂ relativelyÂ thinÂ layerÂ ofÂ looseÂ mix,Â approximatelyÂ equalÂ toÂ theÂ mixtureÂ NMAS.Â 8.2.3 PlaceÂ theÂ pansÂ thatÂ containÂ mixtureÂ inÂ aÂ forcedâdraftÂ ovenÂ atÂ 95Â°CÂ Â±Â 3Â°CÂ forÂ theÂ durationÂ determinedÂ byÂ EquationÂ (1).Â PlaceÂ theÂ pansÂ onÂ differentÂ shelvesÂ soÂ thatÂ theÂ pansÂ areÂ arrangedÂ verticallyÂ withinÂ theÂ ovenÂ asÂ muchÂ asÂ possible.Â EnsureÂ thatÂ adjacentÂ pansÂ doÂ notÂ overlap.Â Â 8.2.4 RotateÂ theÂ pansÂ toÂ differentÂ shelvesÂ atÂ fourÂ evenlyâspacedÂ timeÂ intervalsÂ duringÂ theÂ longâtermÂ conditioningÂ periodÂ soÂ thatÂ eachÂ panÂ hasÂ similarÂ exposureÂ toÂ heatÂ andÂ airÂ flowÂ atÂ differentÂ locationsÂ withinÂ theÂ oven.Â Â 8.2.5 AfterÂ longâtermÂ conditioning,Â removeÂ theÂ conditionedÂ mixturesÂ fromÂ theÂ ovenÂ andÂ mixÂ allÂ ofÂ theÂ mixturesÂ togetherÂ inÂ orderÂ toÂ obtainÂ aÂ uniformÂ mixture.Â 8.2.6 AllowÂ theÂ mixtureÂ toÂ coolÂ toÂ roomÂ temperature.Â TheÂ longâtermÂ conditionedÂ looseÂ mixtureÂ sampleÂ isÂ nowÂ readyÂ forÂ compactionÂ orÂ subsequentÂ testingÂ asÂ required.Â 8.3 PreparingÂ SpecimensÂ fromÂ LooseÂ HMAÂ 8.3.1 SpecimensÂ CompactedÂ UsingÂ theÂ SuperpaveÂ GyratoryÂ CompactorÂ 18.104.22.168 CompactÂ theÂ specimensÂ inÂ accordanceÂ withÂ PPÂ 60.Â CoolÂ theÂ testÂ specimensÂ atÂ roomÂ temperatureÂ forÂ 16Â Â±Â 1Â hour.Â Note 4. Extrude the specimen from the compaction mold after cooling for 2 to 3 hours. Note 5. Specimen cooling usually is scheduled as an overnight step. Cooling may be accelerated by placing the specimen in front of a fan. 8.3.2 SpecimensÂ CompactedÂ UsingÂ theÂ RollingÂ WheelÂ CompactorÂ 22.214.171.124 CompactÂ theÂ specimensÂ inÂ accordanceÂ withÂ PPÂ 3.Â 126.96.36.199 CoolÂ theÂ testÂ specimensÂ atÂ roomÂ temperatureÂ forÂ 16Â Â±Â 1Â hour.Â 188.8.131.52 RemoveÂ theÂ slabÂ fromÂ theÂ mold,Â andÂ sawÂ orÂ coreÂ theÂ requiredÂ specimensÂ fromÂ theÂ slab.Â 9 REPORTÂ 9.1 ReportÂ theÂ binderÂ grade,Â binderÂ contentÂ (toÂ nearestÂ 0.1Â percent),Â andÂ theÂ aggregateÂ typeÂ andÂ gradation,Â ifÂ applicable.Â
127 9.2 ReportÂ theÂ followingÂ longâtermÂ conditioningÂ informationÂ forÂ theÂ performanceÂ testingÂ conditions,Â ifÂ applicable:Â 9.2.1 LongâtermÂ mixtureÂ conditioningÂ temperatureÂ inÂ laboratoryÂ (nearestÂ 1Â°C);Â 9.2.2 LongâtermÂ mixtureÂ conditioningÂ durationÂ inÂ laboratoryÂ (nearestÂ 5Â min);Â andÂ 9.2.3 LaboratoryÂ compactionÂ temperatureÂ (nearestÂ 1Â°C).Â 10 KeywordsÂ 10.1 Conditioning;Â hotÂ mixÂ asphalt;Â longâtermÂ conditioning.Â APPENDICES (Nonmandatory Information) X1. LABORATORY AGING DURATION MAPS X1.1. The CAI values for various locations in the United States were calculated, as described in Section 9, using hourly pavement temperature history data obtained from the EICM to provide an overview of the proposed laboratory aging durations for various climates, field aging durations, and depths. X1.2. The CAI values and measured durations that are needed to match field aging correlate linearly in a one-to-one relationship. Thus, the CAI values represent the required duration at 95Â°C that is needed to match the field aging for a given pavement temperature history and depth. X1.3. Laboratory aging durations were calculated for three field ages: 4 years, 8 years, and 16 years. For each field age, the laboratory aging durations were determined at three depths: 6 mm, 20 mm, and 50 mm, and rounded to the nearest day. X1.4. Figure X1.1 shows the CAI-determined loose mixture aging durations at 95Â°C that are required to match 4, 8, and 16 years of field aging at a depth of 6 mm. Figure X1.1 demonstrates that climate has a significant effect on the required laboratory aging duration that is required to match a given field age.
128 (b) (a)
Figure X pavemen field agin X1.5. X1.6. 1.1-Require t surface fo g. Figure that ar compa Figure requir indica affect A dep layer a structu d oven agin r (a) 4 year X1.2 show e required t rison betwe X1.2 demo ed to match ting that the oxidation le th of 20 mm sphalt mixt re than nea g duration s of field ag s the CAI-d o match 4, 8 en the labor nstrates tha the field agi temperature vels. represents ures becaus rer the surfa 129 at 95Â°C to ing, (b) 8 y etermined lo , and 16 yea atory aging t significant ng at a dept gradient an a reasonable e it better re ce and avoid match leve ears of field ose mixture rs of field a durations pr ly shorter la h of 20 mm d diffusion depth for th flects bulk b s the effect l of field ag aging, and aging durat ging at a dep esented in F boratory agi compared t in pavemen e evaluatio ehavior with of ultraviol ing 6 mm b (c) 16 year ions at 95Â°C th of 20 mm igure X1.1 ng duration o 6 mm, ts significan n of surface in a pavem et oxidation (c) elow s of . A and s are tly ent .
130 (b) (a)
Figure X below pa years of X1.7. X1.8. 1.2-Require vement sur field aging. Figure that ar The re simula indica surfac in a fe pavem term o Based resear mm, b evalua depth layers d oven agin face for (a) X1.3 show e required t sults demon te aging at ting the pres e of the pav w cold north ent surface ven conditi on the resu chers conclu ut does not tion of asph of 50 mm c . g duration 4 years of s the CAI-d o match 4, 8 strate that c a depth of 5 ence of a si ements. In F ern states in in these col oning to mim lts presented ded that lon change appr alt mixtures ould be usef 131 at 95Â°C to field aging, etermined lo , and 16 yea onsiderably 0 mm comp gnificant ox igure X1.3, dicates that d regions are ic field con in the draft g-term agin eciably belo that have b ul for evalua match leve (b) 8 years ose mixture rs of field a shorter agin ared to depth idation grad the required long-term a not signifi ditions. NCHRP Pr g does take w that dept een prepare ting interm l of field ag of field agin aging durat ging at a dep g durations s of 20 mm ient with de aging dura ging at 50 m cant enough oject 9-54 r place below h. Conseque d to match f ediate and b ing 20 mm g, and (c) ions at 95Â°C th of 50 mm are required and 6 mm, pth near the tion of zero m below th to require l eport, the a depth of ntly, the ield aging at ase asphalt (c) 16 . to thus days e ong- 50 a
132 (b) (a)
Figure X below pa years of 1.3-Require vement sur field aging. d oven agin face for (a) g duration 4 years of 133 at 95Â°C to field aging, match leve (b) 8 years l of field ag of field agin ing 50 mm g, and (c) (c) 16