瀝青混合料的應用、理論和原則畢業(yè)設計外文翻譯.doc

1、河北聯合大學輕工學院qinggong college, hebei united university畢業(yè)設計說明書設計（論文）題目：外文翻譯學生姓名： 學 號：200915250522專業(yè)班級：09土木9班 學 部：土木工程部指導教師： 2013年05月30日 附 錄asphalt mixtures-applications, theory and principles1 . applicationsasphalt materials find wide usage in the construction industry. the use of asphalt as a cementing

2、 agent in pavements is the most common of its applications, however, and the one that will be considered here.asphalt products are used to produce flexible pavements for highways and airports. the term “flexible” is used to distinguish these pavements from those made with portland cement, which are

3、classified as rigid pavements, that is, having beam strength. this distinction is important because it provides they key to the design approach which must be used for successful flexible pavement structures.the flexible pavement classification may be further broken down into high and low types, the

4、type usually depending on whether a solid or liquid asphalt product is used. the low types of pavement are made with the cutback, or emulsion, liquid products and are very widely used throughout this country. descriptive terminology has been developed in various sections of the country to the extent

5、 that one pavement type may have several names. however, the general process followed in construction is similar for most low-type pavements and can be described as one in which the aggregate and the asphalt product are usually applied to the roadbed separately and there mixed or allowed to mix, for

6、ming the pavement.the high type of asphalt pavements is made with asphalt cements of some selected penetration grade. fig. 1 a modern asphalt concrete highway. shoulder striping is used as a safely feature.fig. 2 asphalt concrete at the san francisco international airport.they are used when high whe

7、el loads and high volumes of traffic occur and are, therefore, often designed for a particular installation. 2 . theory of asphalt concrete mix designhigh types of flexible pavement are constructed by combining an asphalt cement, often in the penetration grade of 85 to 100, with aggregates that are

8、usually divided into three groups, based on size. the three groups are coarse aggregates, fine aggregates, and mineral filler. these will be discussed in detail in later chapter.each of the constituent parts mentioned has a particular function in the asphalt mixture, and mix proportioning or design

9、is the process of ensuring that no function is neglected. before these individual functions are examined, however, the criteria for pavement success and failure should be considered so that design objectives can be established.a successful flexible pavement must have several particular properties. f

10、irst, it must be stable, that is to resistant to permanent displacement under load. deformation of an asphalt pavement can occur in three ways, two unsatisfactory and one desirable. plastic deformation of a pavement failure and which is to be avoided if possible. compressive deformation of the pavem

11、ent results in a dimensional change in the pavement, and with this change come a loss of resiliency and usually a degree of roughness. this deformation is less serious than the one just described, but it, too, leads to pavement failure. the desirable type of deformation is an elastic one, which actu

12、ally is beneficial to flexible pavements 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

13、 not crack or ravel will probably also protect the roadbed. it must be remembered that flexible pavements transmit loads to the subgrade without significant bridging action, and so a dry firm base is absolutely essential.rapidly moving vehicles depend on the tire-pavement friction factor for control

14、 and safety. the texture of the pavement surfaces must be such that an adequate skid resistance is developed or unsafe conditions result. the design procedure should be used to select the asphalt material and aggregates combination which provides a skid resistant roadway.design procedures which yiel

15、d paving mixtures embodying all these 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-called design method.the final requirement for any pavement is one of e

16、conomy. economy, again, cannot be 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, the requirements for a stable, durable, and safe pavement are met with a reasonable safe

17、ty factor, then the best interests 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

18、is to carry the load imposed on the pavement, and this is accomplished by frictional resistance and interlocking between the individual pieces of aggregates. the carrying capacity of the asphalt pavement is, then, related to the surface texture (particularly that of the fine aggregate) and the densi

19、ty, or “compactness,”, of the aggregates. surface texture varies with different aggregates, and while a rough surface texture is desired, this may not be available in some localities. dense mixtures are obtained by using aggregates that are either naturally or artificially “well graded”. this means

20、that the fine aggregate serves to fill the voids in the 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

21、filler is used, the mixes become gummy and difficult to manage.the asphalt cement in the flexible pavement is used to bind the aggregate particles together and to waterproof the pavements. obtaining the proper asphalt content is extremely important and bears a significant influence on all the items

22、marking a successful pavement. a chief objective of all the design methods which have been developed is to arrive at the best asphalt content for a particular combination of aggregates.3 . mix design principlescertain fundamental principles underlie the design procedures that have been developed. be

23、fore these procedures can be properly studied or applied, some consideration of these principles is necessary. asphalt pavements are composed of aggregates, asphalt cement, and voids. considering the aggregate alone, all the space between particles is void space. the volume of aggregate voids depend

24、s on grading and can vary widely. when the asphalt cement is added, a portion of these aggregate voids is filled 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

25、 are weightless and are usually expressed as a percentage of the total volume of the compacted mixture.an asphalt pavement carries the applied load by particle friction and interlock. if the particles are pushed apart for any reason , then the pavement stability is destroyed. this factor indicates t

26、hat certainly no more asphalt should be added 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 expa

27、nding asphalt will overflow in a condition known as bleeding. the loss of asphalt cement through bleeding weakens the pavement and also reduces surface friction, making the roadway hazardous. fig. 3 cross section of an asphalt concrete pavement showing the aggregate framework bound together by aspha

28、lt 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 should not be exceed. an excess of air voids promotes raveling of the pavement and also permits water to enter and speed up the deteriorating pr

29、ocesses. also, in the presence of excess air the asphalt cement hardens and ages with an accompanying loss of durability and resiliency.the air-void volume of the mix is determined by the degree of compaction as well as by the asphalt content. for a given asphalt content, a lightly compacted mix wil

30、l have a large voids volume and a lower density and a greater strength will result. in the laboratory, the compaction is controlled by using a specified hammer and regulating the number of blows and the energy per blow. in the field, the compaction and the air voids are more difficult to control and

31、 tests must be made no specimens taken from the compacted pavement to cheek on the degree of compaction being obtained. traffic further compact the pavement, and allowance must be made for this in the design. a systematic checking of the pavement over an extended period is needed to given factual in

32、formation for a particular mix. a change in density of several per cent is not unusual, however.asphalt content has been discussed in connection with various facets of the ix design problem. it is a very important factor in the mix design and has a bearing an all the characteristics ld a successful

33、pavement: stability, skid resistance, durability, and economy. as has been mentioned, the various design procedures are intended to provide a means for selecting the asphalt content . these tests will be considered in detail in a future chapter ,but the relationship between asphalt content and the m

34、easurable properties of stability, unit weight, and air voids will be discussed here. fig.4 variations in stability, unit weight, and air-void content with asphalt cement content.if the gradation and type of aggregate, the degree of compaction, and the type of asphalt cement are controlled, then the

35、 strength varies in a predictable manner. the strength will increase up to some optimum asphalt content and then decrease with further additions. the pattern of strength variation will be different when the other mix factors are changed, and so only a typical pattern can be predicted prior to actual

36、 testing.unit weight varies in the same manner as strength when all other variable are controlled. it will reach some peak value at an asphalt content near that determined from the strength curve and then fall off with further additions.as already mentioned, the air-void volume will vary with asphal

37、t content. however, the manner of variation is different in that increased asphalt content will decrease air-void volume to some minimum value which is approached asymptotically. with still greater additions of asphalt material the particles of aggregate are only pushed apart and no change occurs in

38、 air-void volume.in summary, certain principles involving aggregate gradation, air-void volume, asphalt content, and compaction mist be understood before proceeding to actual mix design. the proper design based on these principles will result in sound pavements. if these principles are overlooked, t

39、he pavement may fail by one or more of the recognized modes of failure: shoving, rutting, corrugating, becoming slick when the max is too rich; raveling, cracking, having low durability when the mix is too lean. it should be again emphasized that the strength of flexible is, more accurately, a stabi

40、lity and does not indicate any ability to bridge weak points in the subgrade by beam strength. no asphalt 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 o

41、f those concerned with any aspect of flexible pavement work.譯文：瀝青混合料的應用、理論和原則1、應用瀝青材料如今在建筑行業(yè)廣泛使用。瀝青最常見的應用是作為的瀝青路面的粘結劑使用。然而，這一點必須在這里予以介紹。瀝青產品常用于生產公路和機場柔性路面。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度。這個區(qū)別很重要，因為它提出了成功進行柔性路面結構設計的方法的關鍵。柔性路面的分類可進一步細分為高、低的類別，分類通常取決于是否有使用固體或液體瀝青產品。低類型路面結構類型通過減少瀝青用量或使用乳化劑

42、、液體瀝青，是非常廣泛的應用在全國范圍內。在全國的范圍內各地區(qū)已開發(fā)各自的描述性術語，一個路面類型可能有好幾個名字。但是，一般對大多數低型路面其施工方法確是相似，可描述為瀝青產品通常單獨或其混合結構應用于行車道，形成路面。高級瀝青路面用經過選擇的具有好的滲透性的瀝青混凝土制成。圖1 現代瀝青混凝土公路 路肩設置路標線具有安全地特點 圖2 舊金山國際機場瀝青混凝土跑道它們被用于重荷載和大交通量道路，因此，人們會進行特殊的結構設計。2、瀝青混凝土設計原理高等級柔性路面是用瀝青混凝土建造而成，通常根據集料的85%-100%通過率將其分為三種類型。這三種分別為粗集料、細集料和礦粉。這些將在后面的章節(jié)中

43、進行詳細討論。瀝青混合料的每一個組成部分都有特定的功能，混合料配合比設計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準應該考慮，這樣路面的設計目標才能確定。一個成功的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重，但它也同樣導致路面破壞。理想類型的變形是一種彈性變形，這實際上有利于柔性路面，并對于其長壽命是十

44、分必要的。路面應該耐用并能夠保護路基。瀝青混凝土是受環(huán)境的影響的，因此設計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路基。我們必須記住，柔性路面將荷載直接傳至路基，所以堅實的基礎是絕對必要的。快速移動的車輛依靠的輪胎路面摩擦力實現控制和保證安全。路面表面紋理必須保證足夠的防滑性否則將產生不安全的后果。設計過程通過瀝青材料的選擇和集料的組合設計提供了防滑路面。設計程序放棄鋪面結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過使用時間考驗和規(guī)范和工程判斷和在一起所稱的設計方法選定。對于任何路面最后一個要求是經濟性。經濟性不能一開始就確定，準確的經濟是從開始建設直

45、到路面整個壽命期的成本。然而，如果對于路面穩(wěn)定，耐久，安全性的要求都達到一個合理的安全系數，那么對經濟的最佳利益或許已經實現?？紤]到路面的這些要求，可通過檢查各組成部分的功能如何有助于現在已經確定的目標或要求。瀝青混凝土功能是承擔路面上施加的負荷，這是由混合料各材料之間相互咬合和摩擦阻力實現。也就是瀝青路面的承載能力與路面的表面紋理（尤其是細集料）和密度或者混合料的“密實度”相關，表面結構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現。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。這意味著細骨料的存在填補了粗骨料的空隙。這除了影響混合料的密度和強度特性之外，也影響施工性能。當粗骨料使用過量時，混合料將變得堅硬而且難以施工；當礦物填料使用過多時，混合料將變得較軟，影響使用性能。柔性路面中的瀝青膠結材料用于將集料粘結在一起并充當防水材料。選取適當的瀝青含量是非常重要的，它對于成功的路面在項目的整個評分過程中具有重要的影響。設計的首要目標是對于特定的集料組合