1、外文文獻(xiàn)翻譯原文:Asphalt Mixtures-Applicatio ns, Theory and Prin ciples1 . Applicati onsAsphalt materials find wide usage in the con struct ion in dustry. The use of asphalt as a ceme nting age nt in paveme nts is the most com mon of its applicatio ns, however, and the one that will be consid ered here.Asph

2、alt products are used to produce flexibl e paveme nts for highways and airports. The term “xible ” is used to dist in guish these paveme nts from those made with Portla nd ceme nt, which are classified as rigid pavements, that is, having beam strength. This distinction is importa nt because it provi

3、d es they key to the desig n approach which must be used for successful flexibl e pavement structures.The flexibl e pavement classification may be further broken d own into high and l ow types, the type usually depe nding on whether a solid or liquid asphalt product is used. The l ow types of paveme

4、 nt are mad e with the cutback, or emulsi on liquid products and are very widely used throughout this coun try. Descriptive term ino logy has bee n devel oped in various sect ions of the country to the exte nt that one paveme nt type may have several n ames. However, the gen eral process foll owed i

5、n con struct ion is similar for most low-type paveme nts and can bedescribed as one in which the aggregate and the asphalt product are usually applied to the roadbed separately and there mixed or all owed to mix, forming the paveme nt.The high type of asphalt paveme nts is made with asphalt ceme nts

6、 of some sel ected penetration grad e.Fig. ? A modern asphalt concrete highway. Should er striping is used as a safely feature.Fig. ? Asphalt con crete at the San Fran cisco Intern ati onal Airport.They are used when high wheel l oads and high volumes of traffic occur and are, therefore, often desig

7、ned for a particular installation.2 . Theory of asphalt con crete mix desig nHigh types of flexible paveme nt are con structed by comb ining an asphalt ceme nt, often in the penetration grad e of 85 to 100, with aggregates that are usually divided into three groups, based on size. The three groups a

8、re coarse aggregates, fine aggregates, and mineral filler. These will be discussed in d etail in later chapter.Each of the con stitue nt parts men ti oned has a particular function in the asphalt mixture, and mix proporti oning or d esig n is the process of en suri ng that no function is n eglected.

9、Before these in dividual fun cti ons are exam in ed, however, the criteria for paveme nt success and failure should be consid ered so that d esign objectives can be established.A successful flexible paveme nt must have several particular properties. First, it must be stable, that is to resista nt to

10、 perma nent displaceme nt un der l oad. Deformati on of an asphalt paveme nt can occur in three ways, two un satisfactory and one desirable. Plastic d eformati onof a pavement failure and which is to be avoid ed if possible. Compressive deformation of the pavement results in a dimensional change in

11、the pavement, and with this change come a lossof resiliency and usually a d egree of roughness. This deformation is less serious than the one just described, but it, too, leads to pavement failure. The desirabl e type of deformation is an elastic one, which actually is beneficial to flexibl e paveme

12、nts and is necessary to their long life.The pavement should be durable and should offer protection to the subgrade. Asphalt cement is not impervious to the effects of weathering, and so the design must minimize weather susceptibility. A durable pavement that does not crack or ravel will probably als

13、o protect the roadbed. It must be remembered that fl exible pavements transmit l oads to the subgrade without significant bridging action, and so a dry firm base is absolutely essential.Rapidly moving vehicl es depend on the tire-pavement friction factor for control and safety. The texture of the pa

14、vement surfaces must be such that an adequate skid resistance is developed or unsafe conditions result. The design procedure should be used to sel ect the asphalt material and aggregates combination which provides a skid resistant roadway.Design procedures which yield paving mixtures embodying all t

15、hese properties are not available. Sound pavements are constructed where materials and methods are selected by using time-tested tests and specifications and engineering judgments along with a so-call eddesign method.The final requirement for any pavement is one of economy. Economy, again, cannot be

16、 measured directly, since true economy only begins with construction cost and is not fully determinable until the full useful life of the pavement has been recorded. If, however, therequirements for a stable, durable, and safe pavement are met with a reasonable safety factor, then the best interests

17、 of economy have probably been served as well.With these requirements in mind, the functions of the constituent parts can be examined with consideration give to how each part contributes to now-established objectives or requirements. The functions of the aggregates is to carry the l oad imposed on t

18、he pavement, and this is accomplished by frictional resistance and interlocking between the individualpieces of aggregates. The carrying capacity of the asphalt pavement is, then, related to the surface texture (particularly that of the fine aggregate) and the density, or“ compathe aggregates. Surfa

19、ce texture varies with different aggregates, and while a rough surfacetexture is desired, this may not be available in some l ocalities. Dense mixtures are obtained by using aggregates that are either naturally or artificiallyed”. This mea“nswthealltgtrhaedfineaggregate serves to fill the voids in t

20、he coarser aggregates. In addition to affecting density and therefore strength characteristics, the grading also influences workability. When an excess of coarse aggregate is used, the mix becomes harsh and hard to work. When an excess of mineral filler is used, the mixes become gummy and difficult

21、to manage.The asphalt cement in the fl exibl e pavement is used to bind the aggregate particl es together and to waterproof the pavements. Obtaining the proper asphalt content is extremely important and bears a significant influence on all the items marking a successful pavement. A chief objective o

22、f all the design methods which have been devel oped is to arrive at the best asphalt content for a particular combination of aggregates.3 . Mix design principl esCertain fundamental principles underlie the design procedures that have been developed. Before these procedures can be properly studied or

23、 applied, some consid eration of these principles is necessary.Asphalt pavements are composed of aggregates, asphalt cement, and voids. Consid ering the aggregate alone, all the space between particles is void space. The volume of aggregate voids depends on grading and can vary widely. When the asph

24、alt cement is ad ded, a portion of these aggregate voids is fill ed and a final air-void volume is retained. The retention of this air-void volume is very important to the characteristics of the mixture. The term air-void volume is used, since these voids are weightless and are usually expressed as

25、a percentage of the total volume of the compacted mixture.An asphalt pavement carries the applied load by particl e friction and interlock. If the particl es are pushed apart for any reason , then the pavement stability is d estroyed. This factor indicates that certainly no more asphalt shoul d be a

26、dded than the aggregate voids can readily hold. However ,asphalt cement is susceptible to volume change and the pavement is subject to further compaction under use. If the pavement has no air voids when placed, or if it loses them under traffic, then the expanding asphalt will overflow in a conditio

27、n known asbleeding. The loss of asphalt cement through bl eeding weakens the pavement and also reduces surface friction, making the roadway hazard ous.Coarse ord fine aggregateAsphall cereni ond very fine <iggregoleAir void spoceFig. ?3 Cross section of an asphalt concrete pavement showing the ag

28、gregate framework bound together by asphalt cement.The need for a minimum air-void volume (usually 2 or 3 per cent) has been established.In addition, a maximum air-void volume of 5 to 7 per cent shoul d not be exceed. An excess of air voids promotes raveli ng of the paveme nt and also permits water

29、to en ter and speed up the deteriorati ng processes. Also, in the prese nee of excess air the asphalt ceme nt hard ens and ages with an accompa nying loss of durability and resilie ncy.The air-void volume of the mix is determ ined by the d egree of compacti on as well as by the asphalt content. For

30、a give n asphalt content, a lightly compacted mix will have a large voids volume and a l ower d ensity and a greater strength will result. In the laboratory, the compact ion is con trolled by using a specified hammer and regulat ing the nu mber of blowsand the en ergy per blow. In the fiel d, the co

31、mpacti on and the air voids are more difficult to con trol and tests must be made no specime ns take n from the compacted paveme nt to cheek on the degree of compacti on being obta in ed. Traffic further compact the paveme nt, and allowanee must be mad e for this in the design. A systematic checking

32、 of the pavement over an extended period is needed to given factual information for a particular mix. A change in density of several per cent is not unusual, however.Asphalt content has bee n discussed in connection with various facets of the ix desig n problem. It is a very importa nt factor in the

33、 mix desig n and has a beari ng an all the characteristics ld a successful paveme nt: stability, skid resista nee, durability, and economy. As has bee n men ti on ed, the various desig n procedures are inten ded to provid e a means forselect ing the asphalt content . These tests will be con sidered

34、in detail in a future chapter ,butthe relatio nship betwee n asphalt content and the measurable properties of stability, un itweight, and air voids will be discussed here.£ ntq-fbo»£=phoii 餉川mi, per cent怕“卿h p制 cen!Aphclt onfent, per cenlFig.4 Variations in stability, unit weight, and

35、 air-void content with asphalt cement content.If the gradati on and type of aggregate, the degree of compact ion, and the type of asphaltceme nt are con troll ed, the n the stre ngth varies in a predictable manner. The stre ngth willin crease up to some optimum asphalt content and the n decrease wit

36、h further additi ons. Thepattern of strength variation will be different when the other mix factors are changed, and soonly a typical pattern can be predicted prior to actual testing.Unit weight varies in the same manner as stre ngth whe n all other variabl e are con troll ed.It will reach some peak

37、 value at an asphalt content n ear that determ ined from the stre ngthcurve and the n fall off with further additi ons.As already men ti on ed, the air-void volume will vary with asphalt content. However, themanner of variati on is differe nt in that in creased asphalt content will decrease air-void

38、volume to some mi nimum value which is approached asymptotically. With still greateradditi ons of asphalt material the particles of aggregate are only pushed apart and no cha ngeoccurs in air-void volume.In summary, certain principles involving aggregate gradation, air-void volume, asphaltcontent, a

39、nd compact ion mist be un derstood before proceedi ng to actual mix d esig n. Theproper design based on these principl es will result in sound pavements. If these principles areoverlooked, the pavement may fail by one or more of the recognized modes of failure: shoving,rutting, corrugating, becoming

40、 slick when the max is too richhavingaveling, cracking,low durability whe n the mix is too ean ' . '1It should be again emphasized that the strength of flexible is, more accurately, a stabilityand does not indicate any ability to bridge weak points in the subgrade by beam strength. No asphal

41、t mixture can be successful unless it rests on top of a properly designed and constructed base structure. This fact, that the surface is no better than the base, must be continually in the minds of those concerned with any aspect of flexible pavement work.譯文:瀝青混合料的應(yīng)用、理論和原則1、應(yīng)用瀝青材料如今在建筑行業(yè)廣泛使用。瀝青最常見的應(yīng)

42、用是作為的瀝青路面的 粘結(jié)劑使用。然而，這一點(diǎn)必須在這里予以介紹。瀝青產(chǎn)品常用于生產(chǎn)公路和機(jī)場柔性路面。 所謂“柔性”是用來區(qū)分與硅酸 鹽水泥制成的路面，它被列為剛性路面，也就是這些路面具有剛性強(qiáng)度。 這個區(qū) 別很重要，因?yàn)樗岢隽顺晒M(jìn)行柔性路面結(jié)構(gòu)設(shè)計(jì)的方法的關(guān)鍵。柔性路面的分類可進(jìn)一步細(xì)分為高、低的類別，分類通常取決于是否有使用 固體或液體瀝青產(chǎn)品。低類型路面結(jié)構(gòu)類型通過減少瀝青用量或使用乳化劑、液 體瀝青，是非常廣泛的應(yīng)用在全國范圍內(nèi)。 在全國的范圍內(nèi)各地區(qū)已開發(fā)各自的 描述性術(shù)語，一個路面類型可能有好幾個名字。 但是，一般對大多數(shù)低型路面其 施工方法確是相似，可描述為瀝青產(chǎn)品通常單獨(dú)

43、或其混合結(jié)構(gòu)應(yīng)用于行車道，形成路面。高級瀝青路面用經(jīng)過選擇的具有好的滲透性的瀝青混凝土制成。圖1現(xiàn)代瀝青混凝土公路路肩設(shè)置路標(biāo)線具有安全地特點(diǎn)它們被用于重荷載和大交通量道路，因此，人們會進(jìn)行特殊的結(jié)構(gòu)設(shè)計(jì)。 2、瀝青混凝土設(shè)計(jì)原理高等級柔性路面是用瀝青混凝土建造而成，通常根據(jù)集料的85%-100%通過率將其分為三種類型。 這三種分別為粗集料、 細(xì)集料和礦粉。 這些將在后面的章 節(jié)中進(jìn)行詳細(xì)討論。瀝青混合料的每一個組成部分都有特定的功能， 混合料配合比設(shè)計(jì)是確保沒 有功能被忽略的過程。 然而， 在這些個別功能檢查之前， 對于路面的成功和失敗 的標(biāo)準(zhǔn)應(yīng)該考慮，這樣路面的設(shè)計(jì)目標(biāo)才能確定。一個成功的

44、柔性路面必須有幾個特定的屬性。 首先， 它必須是穩(wěn)定的， 即抵 抗負(fù)荷下的永久位移。 瀝青路面變形的可能發(fā)生在三種方式， 二個是不理想的形 變，一個是可以接受的。 塑性變形對路面來說是要盡量避免的失敗。 路面的壓縮 變形導(dǎo)致的路面鋪裝的尺寸變化， 這種變化將引起路面彈性和粗糙度的損失。 這 種變形沒有剛剛描述的那種那么嚴(yán)重， 但它也同樣導(dǎo)致路面破壞。 理想類型的變 形是一種彈性變形，這實(shí)際上有利于柔性路面，并對于其長壽命是十分必要的。路面應(yīng)該耐用并能夠保護(hù)路基。 瀝青混凝土是受環(huán)境的影響的， 因此設(shè)計(jì)必 須降低對氣候敏感性。 一個耐用的路面要不開裂或擁包才能保護(hù)路基。 我們必須 記住，柔性路面

45、將荷載直接傳至路基，所以堅(jiān)實(shí)的基礎(chǔ)是絕對必要的?？焖僖苿拥能囕v依靠的輪胎路面摩擦力實(shí)現(xiàn)控制和保證安全。 路面表面紋理 必須保證足夠的防滑性否則將產(chǎn)生不安全的后果。 設(shè)計(jì)過程通過瀝青材料的選擇 和集料的組合設(shè)計(jì)提供了防滑路面。設(shè)計(jì)程序放棄鋪面結(jié)合料所有這些表面特性都無法使用。 合理的路面建造所 需的材料和方法是經(jīng)過使用時間考驗(yàn)和規(guī)范和工程判斷和在一起所稱的設(shè)計(jì)方 法選定。對于任何路面最后一個要求是經(jīng)濟(jì)性。 經(jīng)濟(jì)性不能一開始就確定， 準(zhǔn)確的經(jīng) 濟(jì)是從開始建設(shè)直到路面整個壽命期的成本。然而，如果對于路面穩(wěn)定，耐久， 安全性的要求都達(dá)到一個合理的安全系數(shù)，那么對經(jīng)濟(jì)的最佳利益或許已經(jīng)實(shí) 現(xiàn)?？紤]到路面

46、的這些要求， 可通過檢查各組成部分的功能如何有助于現(xiàn)在已經(jīng)確定的目標(biāo)或要求。 瀝青混凝土功能是承擔(dān)路面上施加的負(fù)荷， 這是由混合料各 材料之間相互咬合和摩擦阻力實(shí)現(xiàn)。 也就是瀝青路面的承載能力與路面的表面紋 理（尤其是細(xì)集料）和密度或者混合料的“密實(shí)度”相關(guān)，表面結(jié)構(gòu)隨集料的不 同而不同， 雖然理想的表面具有粗糙紋理， 但在有些情況下卻不能實(shí)現(xiàn)。 密級配 混合物通過使用自然或人為的連續(xù)級配集料得到。 這意味著細(xì)骨料的存在填補(bǔ)了 粗骨料的空隙。 這除了影響混合料的密度和強(qiáng)度特性之外， 也影響施工性能。 當(dāng) 粗骨料使用過量時，混合料將變得堅(jiān)硬而且難以施工；當(dāng)?shù)V物填料使用過多時， 混合料將變得較軟，影響使用性能。柔性路面中的瀝青膠結(jié)材料用于將集料粘結(jié)在一起并充當(dāng)防水材料。 選取適 當(dāng)?shù)臑r青含量是非常重要的， 它對于成功的路面在項(xiàng)目的整個評分過程中具有重 要的影響。設(shè)計(jì)的首要目標(biāo)是對于特定的集料組合確定瀝青的最佳用量。3 、混合料配合比設(shè)計(jì)原則某些基本原則被制定為設(shè)計(jì)程序的基礎(chǔ)程序。 在這些步驟之前， 進(jìn)行某些原 則的的研究或應(yīng)用是很有必要的。瀝青路面由集料、 瀝青膠結(jié)料和空隙組成。