中英文资料外文翻译
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原文：
Asphalt Mixtures-Applications, Theory and Principles
1 . Applications
Asphalt materials find wide usage in the construction industry. The use of asphalt as a cementing agent in pavements is the most common of its applications, however, and the one that will be consid ered here.
Asphalt products are used to produce flexibl e pavements for highways and airports. The term “fl exible” is used to distinguish these pavements from those made with Portland cement, which are classified as rigid pavements, that is, having beam strength. This distinction is important because it provid es they key to the design 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 depending on whether a solid or liquid asphalt product is used. The l ow types of pavement are mad e with the cutback, or emulsion, liquid products and are very widely used throughout this country. Descriptive terminology has been devel oped in various sections of the country to the extent that one pavement type may have several names. However, the general process foll owed in construction is similar for most l ow-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 all owed to mix, forming the pavement.
The high type of asphalt pavements is made with asphalt cements of some sel ected
penetration grad e.
Fig. ·1 A modern asphalt concrete highway. Should er striping is used as a safely feature.
Fig. ·2 Asphalt concrete at the San Francisco International Airport.
They are used when high wheel l oads and high volumes of traffic occur and are, therefore, often designed for a particular installation.
2 . Theory of asphalt concrete mix design
High types of flexible pavement are constructed by combining an asphalt cement, 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 are coarse aggregates, fine aggregates, and mineral filler. These will be discussed in d etail in later chapter.
Each of the constituent parts mentioned has a particular function in the asphalt mixture, and mix proportioning or d esign is the process of ensuring that no function is negl ected. Before these individual functions are examined, however, the criteria for pavement success and failure should be consid ered so that d esign objectives can be established.
A successful fl exible pavement must have several particular properties. First, it must be stable, that is to resistant to permanent displacement under l oad. Deformation of an asphalt pavement can occur in three ways, two unsatisfactory and one desirable. Plastic d eformation
