第九章沥青混合料.docx
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第九章沥青混合料
第九章沥青混合料
本章教学学时：
3.5，其中:
理论课学时:
3；实验学时:
0.5。
本章内容包括沥青混合料的概念、常用类型、组成结构、强度理论及其应用，沥青混合料的组成材料、技术性质、设计的基本要求及方法等。
沥青混合料是重要的路面材料，本章内容是道路与桥梁方面学生学习后续道路技术等专业课程的理论基础，也是道路工程中材料选择与使用的理论依据。
因此，要求同学们密切联系道路工程实际，在了解沥青混合料的概念及组成、常用类型及其特点、组成结构、强度理论及应用，以及组成材料中道路石油沥青和矿质材料常用品种、标准及其选用等知识的基础上，深入地学习沥青混合料的高温稳定性、低温抗裂性、耐久性、等技术性质及测试技术，熟悉沥青混合料的技术标准及选用，掌握混合料的设计基本要求及方法。
学习过程中要注意沥青混合料与沥青混凝土的差异，以及与普通混凝土组成材料及技术性能上的异同。
这部分内容将配合实验及习题进行学习。
本章重点内容包括沥青混合料的技术性质，如高温稳定性、低温抗裂性、耐久性，以及沥青混合料设计方法。
本章教学方式：
课堂授课、实验以及学生自学。
课堂授课采用中（英）文课件、中文讲述；学生自学教材及参考教材、课程教学网站中关于沥青混合料的其它内容。
主要授课内容：
§9.1Introduction
9.1.1WhatisBituminousConcrete?
1.Bituminousmixtureistheadmixturematerialmixedwithmineralandbitumen.
2.Mineral（mineralaggregate,mineralmixture）withbituminousmixtureisspreadandcompactedtoproducebituminousconcrete（AC）orbituminousmacadam（AM）.
9.1.2DefinitionofBituminousMixture
Bituminousmixtureisakindofexcellentpavementmaterialwhichismixedbymineralwithappropriategradationandbitumen.
9.1.3ClassificationofBituminousMixture
1.Bybitumen
（1）Petroleumbituminousadmixturematerial;
（2）Coalbituminousadmixturematerial.
2.Byconstructiontemperature（Fig.9.1.1）
（1）Hot-mixedandhot-spread;
（2）Hot-mixedandcool-spread;
（3）Cool-mixedandcool-spread.
3.Bymaximumparticlediameter（Fig.9.1.2）
（1）Specialcoarsegrade,Dmax=53mm;
（2）Coarsegrade,Dmax=37.5mm、31.5mm;
Fig.9.1.1Spreadconstruction
（3）Mediumgrade,Dmax=26.5mm、19mm;
（4）Finegrade,Dmax=16mm、13.2mm、4.75mm.
4.Bymineralgradation
（1）Continuous;
（2）Discontinuous.
5.Byadmixturematerialcompactnessortheresidualporosityafterpressure
（1）Densegradation;p＜10%
①DensitytypeⅠ;3%~6%
Fig.9.1.2Sieveforparticle
②DensitytypeⅡ;4%~10%
（2）Halfopen-gradation;p＞10%
（3）Open-gradation.p＞15%
9.1.4CharacteristicsofBituminousMixture
1.Goodperformanceinviscosity-elasticity-plasticity,mechanicalproperty,hightemperaturestabilityandhypothermiaflexibility.
2.Goodsecurity.
3.Convenientconstruction.
4.Economicalandenduringuses.
5.Recyclinguses.
§9.2CompositeStructureandStrengthTheory
Itisasortofbituminousmixturethatistypicallyandwidelyusedinengineering.Wewillstudythiskindofmixtureindetails.
9.2.1CompositeStructure
1.Theory
（1）Surfacetheory（Traditionaltheory）：
Bituminousmixtureisproducedintheprocessthatcoarse,fineaggregateandfillerwillmakemineralframeworkwithcompactgradationinscattereddistribution.
（2）Adhesivecementtheory（Moderntheory）：
Bituminousmixtureisamultistagedispersionsystemmadeofmineralmixtureandpitch.
Characteristics:
highconsistency/greatconsumptionofbitumen/discontinuousgradation.
2.Types（Fig.9.2.1）
a-Dense-suspendedtypeb-Framework-intersticetype
c-Dense-frameworktype
Fig.9.2.1Typesofbituminousmixture
3.Typesandcharacteristics（Tab.9.2.1）
Tab.9.2.1Typesandcharacteristicsofbituminousmixture
Types
Sketchmap
Characteristics
Namesofadmixturematerial
Dense-suspendedtype
a
Vvmidst,Φsmall
Continuitydensegrading
Framework-intersticetype
b
Csmall,Vvlarge,Φmidst
Continuityopen-Graded
Dense-frameworktype
c
Clarge,Vvsmall,Φlarge
DiscontinuitydenseGrading
9.2.2StrengthTheory
Twoformsofdestructioninpavementstructure:
1.Normalandhighertemperature-Coulombtheory
（1）Insufficientcohesiondistortion
（2）Insufficientshearresistancedestruction
2.Lowtemperature
Insufficienttensilestrengthdestruction
3.Method-Triaxialsheartest
τ-Shearresistance
C-Cohesion
σ-Shearnormalpressurestress
φ-Angleofinternalfriction
4.Conclusions
Shearresistanceofbituminousmixtureisdeterminedbycohesionandangleofinternalfriction.
9.2.3FactorsinAffectingφandC
1.Influencesofbituminouspropertiestocohesion
Viscosityincreasessothatcohesiongoesupandshearresistanceτclimbs.
2.Reciprocityofbituminousandmineralmaterial
Breezehasadsorptionontheperipheralbituminousmolecule,therefore,theviscositywillbeclosertotheboundarysurfaceandsolventmembrane（10um）diffuses（Fig.9.2.2）.
（1）Internalmembrane—structuralbitumen→strongcohesionC
（2）Externalmembrane—freebitumen→weakcohesionC
3.Effectsofmineralmaterialspecificareaandquantityofbitumen
（1）Effectsofmineralmaterialspecificarea
Thequantityofbitumeniscertain,thegreatermineralmaterialspecificarea,themorestructuralbitumenandstrongerC.
（2）Effectsofquantityofbitumen
Whenbituminousandmineralmaterialsarecertain,thequantityofbituminousmeansthequalityofbitumen/thatofmineralmaterial.
（3）Therelevantcurvebetweenq-Candq-φisshowedinFig.9.2.3.
Fig.9.2.3Therelevantcurvebetweenq-Candq-φ
4.Effectsofmineralmaterialchemistryproperty
Mineralmaterialchemicalpropertyincludes:
（1）Alkalinity,SiO2＜52%;
（2）IndifferenceSiO2=52%-65%;
（3）AciditySiO2＞65%.
Thechangeofmineralmaterialchemicalpropertyplaysanimportantroleinthepropertyofbituminousmixture（Tab.9.2.2）.
Tab.9.2.2Influencesofmineralmaterialchemicalproperty
nameofmineadmixturematerial
drycompressivestrength（KN）
compressivestrengthafterinundation（KN）
strengthreduceafterinundation（%）
limestone
2058
1893
8.01
quartzstone
1176
917
22.08
Causeanalysis:
Alkalinestonecanhavechemicalabsorptionwithbituminousacidanhydrides.TheabsorptionsolventmembranetheyproducedgrowsperfectlytoproducestrongCandhighstrengthofthemixture.Themembraneformedbyacidstoneandbituminousgrowsimperfectlytoproducelowcandpoorstrengthofthemixture.
5.Influencesofmineralgradation,particlediameter,characteristicsofsurfaceshape
（1）Gradation
ContinuousgradationwillhavelowcohesionCandangleofinternalfriction,whilediscontinuousgradation,strongcohesionCandangleofinternalfriction.
（2）Particlediameter
Thebiggerparticlediameter,thebiggerangleofinternalfriction
（3）Grainshapeandroughness
ParticlesareclosetosquareandhaveedgeanglestoproducestrongCandbigφandτ.
（4）Conclusion
Coarseandevenaggregateshouldbechosen.
6.Others
Thehigherthetemperatureis,thelowerC.
Theslowerthespeedofdistortionis,thelowerCandthelowerinfluencesonφ.
§9.3TechnicalPropertyofBituminousMixture
9.3.1HighTemperatureStability
1.Definition
Hightemperaturestabilityrefersthatbituminousmixturecannotformmuchplasticdeformationunderrepeatedloadsathightemperature.
2.Influencingfactors
（1）Bituminouscohesion
（2）Themutualinfluencebetweenbituminousandstone
（3）Thepropertyofthestone
3.Testmethod
（1）Marshalltest:
stability,flowvalue
（2）VBstabilitytest
（3）Triaxialsheartest
（4）Wheelruttest
9.3.2LowTemperatureRupturesResistance
1.Definition
Lowtemperaturecrackresistancerefersthatbituminousadmixturematerialresistsshrinkagedeformationwithoutcracks.
2.Causesofbituminouspavementcracks
①Repeatedloadleadstofatiguecracking;
②Embrittlementinlowtemperatureleadstolowabilitytodeformwithcracking;
③Shrinkageatlowtemperature.
④①+②
3.Effectfactors
（1）Qualityandquantityofbitumen;
（2）Mineralmaterialgradation.
4.Test
Puredrawtest:
→totestthestress,strain,tensilestrengthandlimitingdeformationofthecylinderspecimen;
→tomakeoutthestiffnessmodulusandtheindexoftemperatureshrinkage;
→toevaluatethebreakagetemperatureofbituminousmixture.
9.3.3Durability
1.Definition:
Durabilityrefersthatbituminousmixturehastheabilitytoenduretheinfluenceofatmosphereforalongtimeundertravelingload.
2.Influencingfactors:
Chemicalpropertiesofbitumen,thecomponentofmineralmaterial,thecompositestructureofbituminousmixture,thequantityofbitumen
Forexample:
0.5%reductionofbitumenwillmakeVvriseandmakebituminousmixtureoneyearshorterofitslife.
3.Measuresofimprovingdurability
（1）Employinghardmineralmaterial;
（2）Improvingthedensityofbituminousmixture;
（3）Selectingbituminousmixturewithfineparticlesanddensegradation;
（4）Increasingthequantityofbituminous.
4.Test
（1）Acceleratedweatheringtest
（2）Marshalltest
Durabilitycanbeevaluatedbytheindexofavailableporosity,saturationdegreebituminousinterstitialrateandresidualstability.
9.3.4SkidResistance
1.Influencingfactors
（1）Mineralmaterialsurfacestructure
（2）Gradation
（3）Compositesofmixture
（4）Quantityofbitumen
2.Improvingmeasures
（1）Selectinganti-frictionstonewithrequiredrateofwearandimpactvalue.
Notice:
itisnecessarytoaddsomeanti-strippingagentbecausethehardstoneoftenbelongstotheacidstone.
（2）Controllingthequantityofbituminous
Ifthequantityofbituminousgoesup→sharpnessofthesurfacewillincreaseandtheanti-slidedrops.
9.3.5ConstructionWorkability
Constructionworkabilityisdeterminedby:
（1）Mineralmaterial’sgradation:
itisnoteasytooccurringisolationwithappropriategradation;
（2）Cohesionandquantityofbitumen;
（3）Temperatureandconstructioncondition.
§9.4CompositeMaterialofBituminousMixture
9.4.1BituminousMaterial-roadPetroleumBitumen
1.Classification
（1）Heavypavementpetroleumbitumen
（2）Medium,lightpavementpetroleumbitumen
2.Heavypavementpetroleumbitumen
（1）Tab
AH-50、AH-70、AH-90、AH-110、AH-130
（2）Application
Highwayroad,roadsurfaceofarterialhighway,roadsurfaceofairportandroadsurfaceofimportantcityroad
（3）Technicalstandardofheavypavementoilbitumen（Tab.9.4.1）
Tab.9.4.1Technicalstandardofheavypavementbitumen
Testitems
AH-130
AH-110
AH-90
AH-70
AH-50
Penetra
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