道路工程外文文献翻译

外文文献翻译原文：AsphaltMixtures-Applications,TheoryandPrinciples1.ApplicationsAsphaltmaterialsfindwideusageintheconstructionindustry.Theuseofasphaltasacementingagentinpavementsisthemostcommonofitsapplications,however,andtheonethatwillbeconsideredhere.Asphaltproductsareusedtoproduceflexiblepavementsforhighwaysandairports.Theterm“flexible”isusedtodistinguishthesepavementsfromthosemadewithPortlandcement,whichareclassifiedasrigidpavements,thatis,havingbeamstrength.Thisdistinctionisimportantbecauseitprovidestheykeytothedesignapproachwhichmustbeusedforsuccessfulflexiblepavementstructures.Theflexiblepavementclassificationmaybefurtherbrokendownintohighandlowtypes,thetypeusuallydependingonwhetherasolidorliquidasphaltproductisused.Thelowtypesofpavementaremadewiththecutback,oremulsion,liquidproductsandareverywidelyusedthroughoutthiscountry.Descriptiveterminologyhasbeendevelopedinvarioussectionsofthecountrytotheextentthatonepavementtypemayhaveseveralnames.However,thegeneralprocessfollowedinconstructionissimilarformostlow-typepavementsandcanbedescribedasoneinwhichtheaggregateandtheasphaltproductareusuallyappliedtotheroadbedseparatelyandtheremixedorallowedtomix,formingthepavement.Thehightypeofasphaltpavementsismadewithasphaltcementsofsomeselectedpenetrationgrade.Fig."lAmodernasphaltconcretehighway.Shoulderstripingisusedasasafelyfeature.Fig.・2AsphaltconcreteattheSanFranciscoInternationalAirport.Theyareusedwhenhighwheelloadsandhighvolumesoftrafficoccurandare,therefore,oftendesignedforaparticularinstallation.2.TheoryofasphaltconcretemixdesignHightypesofflexiblepavementareconstructedbycombininganasphaltcement,ofteninthepenetrationgradeof85to100,withaggregatesthatareusuallydividedintothreegroups,basedonsize.Thethreegroupsarecoarseaggregates,fineaggregates,andmineralfiller.Thesewillbediscussedindetailinlaterchapter.Eachoftheconstituentpartsmentionedhasaparticularfunctionintheasphaltmixture,andmixproportioningordesignistheprocessofensuringthatnofunctionisneglected.Beforetheseindividualfunctionsareexamined,however,thecriteriaforpavementsuccessandfailureshouldbeconsideredsothatdesignobjectivescanbeestablished.Asuccessfulflexiblepavementmusthaveseveralparticularproperties.First,itmustbestable,thatistoresistanttopermanentdisplacementunderload.Deformationofanasphaltpavementcanoccurinthreeways,twounsatisfactoryandonedesirable.Plasticdeformationofapavementfailureandwhichistobeavoidedifpossible.Compressivedeformationofthepavementresultsinadimensionalchangeinthepavement,andwiththischangecomealossofresiliencyandusuallyadegreeofroughness.Thisdeformationislessseriousthantheonejustdescribed,butit,too,leadstopavementfailure.Thedesirabletypeofdeformationisanelasticone,whichactuallyisbeneficialtoflexiblepavementsandisnecessarytotheirlonglife.Thepavementshouldbedurableandshouldofferprotectiontothesubgrade.Asphaltcementisnotimpervioustotheeffectsofweathering,andsothedesignmustminimizeweathersusceptibility.Adurablepavementthatdoesnotcrackorravelwillprobablyalsoprotecttheroadbed.Itmustberememberedthatflexiblepavementstransmitloadstothesubgradewithoutsignificantbridgingaction,andsoadryfirmbaseisabsolutelyessential.Rapidlymovingvehiclesdependonthetire-pavementfrictionfactorforcontrolandsafety.Thetextureofthepavementsurfacesmustbesuchthatanadequateskidresistanceisdevelopedorunsafeconditionsresult.Thedesignprocedureshouldbeusedtoselecttheasphaltmaterialandaggregatescombinationwhichprovidesaskidresistantroadway.Designprocedureswhichyieldpavingmixturesembodyingallthesepropertiesarenotavailable.Soundpavementsareconstructedwherematerialsandmethodsareselectedbyusingtime-testedtestsandspecificationsandengineeringjudgmentsalongwithaso-calleddesignmethod.Thefinalrequirementforanypavementisoneofeconomy.Economy,again,cannotbemeasureddirectly,sincetrueeconomyonlybeginswithconstructioncostandisnotfullydeterminableuntilthefullusefullifeofthepavementhasbeenrecorded.If,however,therequirementsforastable,durable,andsafepavementaremetwithareasonablesafetyfactor,thenthebestinterestsofeconomyhaveprobablybeenservedaswell.Withtheserequirementsinmind,thefunctionsoftheconstituentpartscanbeexaminedwithconsiderationgivetohoweachpartcontributestonow-establishedobjectivesorrequirements.Thefunctionsoftheaggregatesistocarrytheloadimposedonthepavement,andthisisaccomplishedbyfrictionalresistanceandinterlockingbetweentheindividualpiecesofaggregates.Thecarryingcapacityoftheasphaltpavementis,then,relatedtothesurfacetexture(particularlythatofthefineaggregate)andthedensity,or“compactness,”,oftheaggregates.Surfacetexturevarieswithdifferentaggregates,andwhilearoughsurfacetextureisdesired,thismaynotbeavailableinsomelocalities.Densemixturesareobtainedbyusingaggregatesthatareeithernaturallyorartificially“wellgraded”.Thismeansthatthefineaggregateservestofillthevoidsinthecoarseraggregates.Inadditiontoaffectingdensityandthereforestrengthcharacteristics,thegradingalsoinfluencesworkability.Whenanexcessofcoarseaggregateisused,themixbecomesharshandhardtowork.Whenanexcessofmineralfillerisused,themixesbecomegummyanddifficulttomanage.Theasphaltcementintheflexiblepavementisusedtobindtheaggregateparticlestogetherandtowaterproofthepavements.Obtainingtheproperasphaltcontentisextremelyimportantandbearsasignificantinfluenceonalltheitemsmarkingasuccessfulpavement.Achiefobjectiveofallthedesignmethodswhichhavebeendevelopedistoarriveatthebestasphaltcontentforaparticularcombinationofaggregates.3.MixdesignprinciplesCertainfundamentalprinciplesunderliethedesignproceduresthathavebeendeveloped.Beforetheseprocedurescanbeproperlystudiedorapplied,someconsiderationoftheseprinciplesisnecessary.Asphaltpavementsarecomposedofaggregates,asphaltcement,andvoids.Consideringtheaggregatealone,allthespacebetweenparticlesisvoidspace.Thevolumeofaggregatevoidsdependsongradingandcanvarywidely.Whentheasphaltcementisadded,aportionoftheseaggregatevoidsisfilledandafinalair-voidvolumeisretained.Theretentionofthisair-voidvolumeisveryimportanttothecharacteristicsofthemixture.Thetermair-voidvolumeisused,sincethesevoidsareweightlessandareusuallyexpressedasapercentageofthetotalvolumeofthecompactedmixture.Anasphaltpavementcarriestheappliedloadbyparticlefrictionandinterlock.Iftheparticlesarepushedapartforanyreason,thenthepavementstabilityisdestroyed.Thisfactorindicatesthatcertainlynomoreasphaltshouldbeaddedthantheaggregatevoidscanreadilyhold.However,asphaltcementissusceptibletovolumechangeandthepavementissubjecttofurthercompactionunderuse.Ifthepavementhasnoairvoidswhenplaced,orifitlosesthemundertraffic,thentheexpandingasphaltwilloverflowinaconditionknownasbleeding.Thelossofasphaltcementthroughbleedingweakensthepavementandalsoreducessurfacefriction,makingtheroadwayhazardous.

CoarseandtineoggregoteAsphalicemenlandveryfine<]qqrega-leAirvoi{£sp<iceFig.，3Crosssectionofanasphaltconcretepavementshowingtheaggregateframeworkboundtogetherbyasphaltcement.Theneedforaminimumair-voidvolume(usually2or3percent)hasbeenestablished.Inaddition,amaximumair-voidvolumeof5to7percentshouldnotbeexceed.Anexcessofairvoidspromotesravelingofthepavementandalsopermitswatertoenterandspeedupthedeterioratingprocesses.Also,inthepresenceofexcessairtheasphaltcementhardensandageswithanaccompanyinglossofdurabilityandresiliency.Theair-voidvolumeofthemixisdeterminedbythedegreeofcompactionaswellasbytheasphaltcontent.Foragivenasphaltcontent,alightlycompactedmixwillhavealargevoidsvolumeandalowerdensityandagreaterstrengthwillresult.Inthelaboratory,thecompactioniscontrolledbyusingaspecifiedhammerandregulatingthenumberofblowsandtheenergyperblow.Inthefield,thecompactionandtheairvoidsaremoredifficulttocontrolandtestsmustbemadenospecimenstakenfromthecompactedpavementtocheekonthedegreeofcompactionbeingobtained.Trafficfurthercompactthepavement,andallowancemustbemadeforthisinthedesign.Asystematiccheckingofthepavementoveranextendedperiodisneededtogivenfactualinformationforaparticularmix.Achangeindensityofseveralpercentisnotunusual,however.Asphaltcontenthasbeendiscussedinconnectionwithvariousfacetsoftheixdesignproblem.Itisaveryimportantfactorinthemixdesignandhasabearinganallthecharacteristicsldasuccessfulpavement：stability,skidresistance,durability,andeconomy.Ashasbeenmentioned,thevariousdesignproceduresareintendedtoprovideameansforselectingtheasphaltcontent.Thesetestswillbeconsideredindetailinafuturechapter,but

therelationshipbetweenasphaltcontentandthemeasurablepropertiesofstability,unitweight,andairvoidswillbediscussedhere.AsphcltcofiianijpercentAsphdfcooiefi!,perceniAsphcltcofiianijpercentAsphdfcooiefi!,perceniFig.4Variationsinstability,unitweight,andair-voidcontentwithasphaltcementcontent.Ifthegradationandtypeofaggregate,thedegreeofcompaction,andthetypeofasphaltcementarecontrolled,thenthestrengthvariesinapredictablemanner.Thestrengthwillincreaseuptosomeoptimumasphaltcontentandthendecreasewithfurtheradditions.Thepatternofstrengthvariationwillbedifferentwhentheothermixfactorsarechanged,andsoonlyatypicalpatterncanbepredictedpriortoactualtesting.Unitweightvariesinthesamemannerasstrengthwhenallothervariablearecontrolled.Itwillreachsomepeakvalueatanasphaltcontentnearthatdeterminedfromthestrengthcurveandthenfalloffwithfurtheradditions.Asalreadymentioned,theair-voidvolumewillvarywithasphaltcontent.However,themannerofvariationisdifferentinthatincreasedasphaltcontentwilldecreaseair-voidvolumetosomeminimumvaluewhichisapproachedasymptotically.Withstillgreateradditionsofasphaltmaterialtheparticlesofaggregateareonlypushedapartandnochangeoccursinair-voidvolume.Insummary,certainprinciplesinvolvingaggregategradation,air-voidvolume,asphaltcontent,andcompactionmistbeunderstoodbeforeproceedingtoactualmixdesign.Theproperdesignbasedontheseprincipleswillresultinsoundpavements.Iftheseprinciplesareoverlooked,thepavementmayfailbyoneormoreoftherecognizedmodesoffailure：shoving,rutting,corrugating,becomingslickwhenthemaxistoo‘rich';raveling,cracking,havinglowdurabilitywhenthemixistoo'lean'.Itshouldbeagainemphasizedthatthestrengthofflexibleis,moreaccurately,astabilityanddoesnotindicateanyabilitytobridgeweakpointsinthesubgradebybeamstrength.Noasphaltmixturecanbesuccessfulunlessitrestsontopofaproperlydesignedandconstructedbasestructure.Thisfact,thatthesurfaceisnobetterthanthebase,mustbecontinuallyinthemindsofthoseconcernedwithanyaspectofflexiblepavementwork.译文:沥青混合料的应用、理论和原则1、应用沥青材料如今在建筑行业广泛使用。沥青最常见的应用是作为的沥青路面的粘结剂使用。然而，这一点必须在这里予以介绍。沥青产品常用于生产公路和机场柔性路面。所谓“柔性”是用来区分与硅酸盐水泥制成的路面，它被列为刚性路面，也就是这些路面具有刚性强度。这个区别很重要，因为它提出了成功进行柔性路面结构设计的方法的关键。柔性路面的分类可进一步细分为高、低的类别，分类通常取决于是否有使用固体或液体沥青产品。低类型路面结构类型通过减少沥青用量或使用乳化剂、液体沥青，是非常广泛的应用在全国范围内。在全国的范围内各地区已开发各自的描述性术语，一个路面类型可能有好几个名字。但是，一般对大多数低型路面其施工方法确是相似，可描述为沥青产品通常单独或其混合结构应用于行车道，形成路面。高级沥青路面用经过选择的具有好的渗透性的沥青混凝土制成。图1现代沥青混凝土公路路肩设置路标线具有安全地特点图2旧金山国际机场沥青混凝土跑道它们被用于重荷载和大交通量道路，因此，人们会进行特殊的结构设计。2、沥青混凝土设计原理高等级柔性路面是用沥青混凝土建造而成，通常根据集料的85%-100%通过率将其分为三种类型。这三种分别为粗集料、细集料和矿粉。这些将在后面的章节中进行详细讨论。沥青混合料的每一个组成部分都有特定的功能，混合料配合比设计是确保没有功能被忽略的过程。然而，在这些个别功能检查之前，对于路面的成功和失败的标准应该考虑，这样路面的设计目标才能确定。一个成功的柔性路面必须有几个特定的属性。首先，它必须是稳定的，即抵抗负荷下的永久位移。沥青路面变形的可能发生在三种方式，二个是不理想的形变，一个是可以接受的。塑性变形对路面来说是要尽量避免的失败。路面的压缩变形导致的路面铺装的尺寸变化，这种变化将引起路面弹性和粗糙度的损失。这种变形没有刚刚描述的那种那么严重，但它也同样导致路面破坏。理想类型的变形是一种弹性变形，这实际上有利于柔性路面，并对于其长寿命是十分必要的。路面应该耐用并能够保护路基。沥青混凝土是受环境的影响的，因此设计必须降低对气候敏感性。一个耐用的路面要不开裂或拥包才能保护路基。我们必须记住，柔性路面将荷载直接传至路基，所以坚实的基础是绝对必要的。快速移动的车辆依靠的轮胎路面摩擦力实现控制和保证安全。路面表面纹理必须保证足够的防滑性否则将产生不安全的后果。设计过程通过沥青材料的选择和集料的组合设计提供了防滑路面。设计程序放弃铺面结合料所有这些表面特性都无法使用。合理的路面建造所需的材料和方法是经过使用时间考验和规范和工程判断和在一起所称的设计方法选定。对于任何路面最后一个要求是经济性。经济性不能一开始就确定，准确的经济是从开始建设直到路面整个寿命期的成本。然而，如果对于路面稳定，耐久，安全性的要求都达到一个合理的安全系数，那么对经济的最佳利益或许已经实现。考虑到路面的这些要求，可通过检查各组成部分的功能如何有助于现在已经确定的目标或要求。沥青混凝土功能是承担路面上施加的负荷，这是由混合料各材料之间相互咬合和摩擦阻力实现。也就是沥青路面的承载能力与路面的表面纹理（尤其是细集料）和密度或者混合料的“密实度”相关，表面结构随集料的不同而不同，虽然理想的表面具有粗糙纹理，但在有些情况下却不能实现。密级配混合物通过使用自然或人为的连续级配集料得到。这意味着细骨料的存在填补了粗骨料的空隙。这除了影响混合料的密度和强度特性之外，也影响施工性能。当粗骨料使用过量时，混合料将变得坚硬而且难以施工；当矿物填料使用过多时，混合料将变得较软，影响使用性能。柔性路面中的沥青胶结材料用于将集料粘结在一起并充当防水材料。选取适当的沥青含量是非常重要的，它对于成功的路面在项目的整个评分过程中具有重要的影响。设计的首要目标是对于特定的集料组合确定沥青的最佳用量。3、混合料配合比设计原则某些基本原则被制定为设计程序的基础程序。在这些步骤之前，进行某些原则的的研究或应用是很有必要的。沥青路面由集料、沥青胶结料和空隙组成。对于单独的集料颗粒而言，它的周围都是空隙空间，寂寥的空隙率和集料分级有关系并会在很大的范围内变化。当沥青用量增加时，一部分集料的空隙将被填充，最后的空气空隙将得到保留。这部分保留的空气空隙对于混合料的特性是非常重要的。因为这些空隙没有质量，因而常以体积计算，并通常作为混合料的