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1、FHWA Condensed SuperpaveAsphalt Specifications Lecture Series,SUPERPAVE,Aggregates,Usually refers to a soil that has in some way been processed or sorted.,Aggregate Size Definitions,Nominal Maximum Aggregate Sizeone size larger than the first sieve to retain more than 10%Maximum Aggregate Sizeone si
2、ze larger than nominal maximum size,100,0,.075.3 2.36 4.759.512.5 19.0,Percent Passing,control point,restricted zone,max density line,maxsize,nommaxsize,Sieve Size(mm)Raised to 0.45 Power,Superpave Aggregate Gradation,100,0,.075.3 2.36 12.5 19.0,Percent Passing,Design Aggregate Structure,Sieve Size(
3、mm)Raised to 0.45 Power,Superpave Mix Size Designations,Superpave Nom Max Size Max SizeDesignation(mm)(mm)37.5 mm 37.5 50 25 mm 25 37.5 19 mm 19 25 12.5 mm 12.5 19 9.5 mm 9.5 12.5,Gradations,*Considerations:,-Max.size 1/2 AC lift thickness,+Increases strength,+Improves skid resistance,+Increases vol
4、ume and surface area of agg which decreases required AC content,+Improves rut resistance+Increases problem with segregation of particles,-Smaller max size,+Reduces segregation,+Reduces road noise,+Decreases tire wear,Percent Crushed Fragments in Gravels,Quarried materials always 100%crushedMinimum v
5、alues depended upon traffic level and layer(lift)Defined as%mass with one or more fractured faces,Percent Crushed Fragments in Gravels,0%Crushed 100%with 2 or More Crushed Faces,Coarse Aggregate Angularity Criteria,First number denotes%with one or more fractured facesSecond number denotes%with two o
6、r more fractured faces,Asphalt Cements,BackgroundHistory of Specifications,Background,Asphalt Soluble in petroleum products Generally a by-product of petroleum distillation processCan be naturally occurring,TarResistant to petroleum productsGenerally by-product of coke(from coal)production,Penetrati
7、on Testing,Sewing machine needleSpecified load,time,temperature,Penetration Specification,Five Grades 40-50 60-70 85-100 120-150 200-300,Ductility,Typical Penetration Specifications,Penetration 40-50200-300,Flash Point,C 450+350+,Ductility,cm 100+100+,Solubility,%99.0+99.0+,Retained Pen.,%55+37+,Duc
8、tility,cm NA 100+,Viscosity Graded Specifications,Types of Viscosity Tubes,Asphalt Institute Tube,Zietfuchs Cross-Arm Tube,Table 1 Example,AC 2.5AC 40,Visc,60C 250+50 4,000+800,Visc,135C 80+300+,Penetration 200+20+,Visc,60C1,250 20,000,Ductility 100+10+,100,50,10,5,Viscosity,60C(140F),Asphalt Cement
9、s,New Superpave Performance Graded Specification,PG Specifications,Fundamental properties related to pavement performanceEnvironmental factorsIn-service&construction temperaturesShort and long term aging,High Temperature Behavior,High in-service temperatureDesert climatesSummer temperaturesSustained
10、 loadsSlow moving trucksIntersections,Viscous Liquid,Pavement Behavior(Warm Temperatures),Permanent deformation(rutting)Mixture is plasticDepends on asphalt source,additives,and aggregate properties,Permanent Deformation,Function of warm weather and traffic,Courtesy of FHWA,Low Temperature Behavior,
11、Low TemperatureCold climatesWinterRapid LoadsFast moving trucks,Elastic Solid,s=t E,Hookes Law,Pavement Behavior(Low Temperatures),Thermal cracksStress generated by contraction due to drop in temperatureCrack forms when thermal stresses exceed ability of material to relieve stress through deformatio
12、nMaterial is brittleDepends on source of asphalt and aggregate properties,Thermal Cracking,Courtesy of FHWA,Superpave Asphalt Binder Specification,The grading system is based on Climate,PG 64-22,Performance Grade,Average 7-day max pavement temperature,Min pavement temperature,Pavement Temperatures a
13、re Calculated,Calculated by Superpave softwareHigh temperature 20 mm below the surface of mixtureLow temperatureat surface of mixture,Pave temp=f(air temp,depth,latitude),Concentric Cylinder,Concentric Cylinder Rheometers,Dynamic Shear Rheometer(DSR),Parallel Plate,Shear flow varies with gap height
14、and radiusNon-homogeneous flow,Short Term Binder Aging,Rolling Thin Film OvenSimulates aging from hot mixing and construction,Pressure Aging Vessel(Long Term Aging),Simulates aging of an asphalt binder for 7 to 10 years50 gram sample is aged for 20 hoursPressure of 2,070 kPa(300 psi)At 90,100 or 110
15、 C,Bending Beam Rheometer,Air Bearing,Load Cell,Deflection Transducer,Fluid Bath,Computer,Direct Tension Test,D Le,D L,Load,Stress=s=P/A,Strain,ef,sf,Summary,FatigueCracking,Rutting,Construction,RV,DSR,Low TempCracking,BBR,DTT,Superpave Binder Purchase Specification,Superpave Asphalt Binder Specific
16、ation,The grading system is based on Climate,PG 64-22,Performance Grade,Average 7-day max pavement temperature,Min pavement temperature,PG 46 PG 52 PG 58 PG 64 PG 70 PG 76 PG 82,(Rotational Viscosity)RV,90 90 100 100 100(110)100(110)110(110),(Flash Point)FP,46 52 58 64 70 76 82,46 52 58 64 70 76 82,
17、(ROLLING THIN FILM OVEN)RTFO Mass Loss 1.00%,(Direct Tension)DT,(Bending Beam Rheometer)BBR Physical Hardening,28,-34-40-46-10-16-22-28-34-40-46-16-22-28-34-40-10-16-22-28-34-40-10-16-22-28-34-40-10-16-22-28-34-10-16-22-28-34,Avg 7-day Max,oC,1-day Min,oC,(PRESSURE AGING VESSEL)PAV,ORIGINAL,1.00 kPa
18、,5000 kPa,2.20 kPa,S 300 MPa,m 0.300,Report Value,1.00%,20 Hours,2.07 MPa,10 7 4 25 22 19 16 13 10 7 25 22 19 16 13 31 28 25 22 19 16 34 31 28 25 22 19 37 34 31 28 25 40 37 34 31,(Dynamic Shear Rheometer)DSR G*sin,(Bending Beam Rheometer)BBR“S”Stiffness&“m”-value,-24-30-36 0-6-12-18-24-30-36-6-12-18
19、-24-30 0-6-12-18-24-30 0-6-12-18-24-30 0-6-12-18-24 0-6-12-18-24,-24-30-36 0-6-12-18-24-30-36-6-12-18-24-30 0-6-12-18-24-30 0-6-12-18-24-30 0-6-12-18-24 0-6-12-18-24,Performance Grades,(Dynamic Shear Rheometer)DSR G*/sin,(Dynamic Shear Rheometer)DSR G*/sin,3 Pa.s 135 oC,230 oC,CEC,PG 46 PG 52 PG 58
20、PG 64 PG 70 PG 76 PG 82,(Rotational Viscosity)RV,90 90 100 100 100(110)100(110)110(110),(Flash Point)FP,46 52 58 64 70 76 82,46 52 58 64 70 76 82,(ROLLING THIN FILM OVEN)RTFO Mass Loss 1.00%,(Direct Tension)DT,(Bending Beam Rheometer)BBR Physical Hardening,28,-34-40-46-10-16-22-28-34-40-46-16-22-28-
21、34-40-10-16-22-28-34-40-10-16-22-28-34-40-10-16-22-28-34-10-16-22-28-34,Avg 7-day Max,oC,1-day Min,oC,(PRESSURE AGING VESSEL)PAV,ORIGINAL,5000 kPa,2.20 kPa,S 300 MPa,m 0.300,Report Value,1.00%,20 Hours,2.07 MPa,10 7 4 25 22 19 16 13 10 7 25 22 19 16 13 31 28 25 22 19 16 34 31 28 25 22 19 37 34 31 28
22、 25 40 37 34 31,(Dynamic Shear Rheometer)DSR G*sin,(Bending Beam Rheometer)BBR“S”Stiffness&“m”-value,-24-30-36 0-6-12-18-24-30-36-6-12-18-24-30 0-6-12-18-24-30 0-6-12-18-24-30 0-6-12-18-24 0-6-12-18-24,-24-30-36 0-6-12-18-24-30-36-6-12-18-24-30 0-6-12-18-24-30 0-6-12-18-24-30 0-6-12-18-24 0-6-12-18-
23、24,How the PG Spec Works,(Dynamic Shear Rheometer)DSR G*/sin,(Dynamic Shear Rheometer)DSR G*/sin,3 Pa.s 135 oC,230 oC,CEC,Test TemperatureChanges,Spec RequirementRemains Constant,1.00 kPa,PG 58-22,PG 52-28,PG 64-10,PG 58-16,Many agencies have established zones,PG Binder Selection,Summary of How to U
24、se PG Specification,Determine 7-day max pavement temperatures1-day minimum pavement temperatureUse specification tables to select test temperaturesDetermine asphalt cement properties and compare to specification limits,Asphalt Concrete Mix Design,History,Hot Mix Asphalt Concrete(HMA)Mix Designs,Obje
25、ctive:Develop an economical blend of aggregates and asphalt that meet design requirementsHistorical mix design methodsMarshall HveemNew Superpave gyratory,Requirements in Common,Sufficient asphalt to ensure a durable pavementSufficient stability under traffic loadsSufficient air voidsUpper limit to
26、prevent excessive environmental damageLower limit to allow room for initial densification due to trafficSufficient workability,MARSHALL MIX DESIGN,Marshall Mix Design,Developed by Bruce Marshall for the Mississippi Highway Department in the late 30sWES began to study it in 1943 for WWIIEvaluated com
27、paction effortNo.of blows,foot design,etc.Decided on 10 lb.Hammer,50 blows/side4%voids after trafficInitial criteria were established and upgraded for increased tire pressures and loads,Marshall Mix Design,Select and test aggregateSelect and test asphalt cementEstablish mixing and compaction tempera
28、turesDevelop trial blendsHeat and mix asphalt cement and aggregatesCompact specimen(100 mm diameter),Marshall Design Criteria,Light TrafficMedium Traffic Heavy Traffic ESAL 106,Compaction 35 50 75Stability N(lb.)3336(750)5338(1200)8006(1800)Flow,0.25 mm(0.1 in)8 to 18 8 to 16 8 to 14Air Voids,%3 to
29、5 3 to 5 3 to 5Voids in Mineral Agg.(VMA)Varies with aggregate size,Asphalt Concrete Mix Design,Superpave,Superpave Volumetric Mix Design,GoalsCompaction method which simulates field Accommodates large size aggregatesMeasure of compactibilityAble to use in field labsAddress durability issuesFilm thi
30、cknessEnvironmental,reactionframe,rotatingbase,loadingram,control and dataacquisition panel,mold,heightmeasurement,tilt bar,Key Components of Gyratory Compactor,Compaction,Compaction,Gyratory compactorAxial and shearing action150 mm diameter moldsAggregate size up to 37.5 mmHeight measurement during
31、 compactionAllows densification during compaction to be evaluated,1.25o,Ram pressure600 kPa,%Gmm,Log Gyrations,101001000,Nini,Ndes,Nmax,Three Points on SGC Curve,SGC Critical Point Comparison,%Gmm=Gmb/Gmm Gmb=Bulk Mix Specific Gravity from compaction at N cyclesGmm=Max.Theoretical Specific GravityCo
32、mpare to allowable values at:NINI:%Gmm 89%NDES:%Gmm 96%NMAX:%Gmm 98%,Design Compaction,Ndes based onaverage design high air temptraffic levelLog Nmax=1.10 Log Ndes Log Nini=0.45 Log Ndes,%Gmm,Log Gyrations,10 100 1000,Nini,Ndes,Nmax,Superpave Testing,Specimen heightsMixture volumetricsAir voidsVoids
33、 in mineral aggregate(VMA)Voids filled with asphalt(VFA)Mixture density characteristicsDust proportionMoisture sensitivity,Superpave Mix Design,Determine mix properties at NDesign and compare to criteriaAir voids 4%(or 96%Gmm)VMA See tableVFA See table%Gmm at Nini 89%Gmmat Nmax 98%Dust proportion 0.6 to 1.2,VMA requirements:Nominal max agg sizeMin.VMA 9.5 mm15 12.5 mm14 19 mm13 35 mm12 37.5 mm11,Superpave Mix Design,VFA requirements:Traffic(millions of ESALs)Range of VFA,Superpave Mix Design,3.065 to 75,
