毕业设计-道路工程(路桥)毕业设计外文文献翻译【值得参考】.docVIP

外文文献翻译 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 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 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 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 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, forming 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 wheel loads 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 grade of 85 to 100, with aggregates that are usually