Pavement structural characteristics

Details of the drainage coefficients for the five drainage levels considered are given in 

The estimation of the proper drainage coefficient (w,) is subjective and depends on the judgment and experience of the designer. The value of the coefficient wt, = 1.00 is taken when drainage quality is fair and pavement is exposed to moisture levels approaching saturation, that is, 5% of its service life. 

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Finally, pavement structural characteristics and, particularly for flexible pavements, drainage belong to the fourth category. 

The history of post-construction works, if carried out, must be known in detail. This provides valuable information on estimating rates of deterioration for locally existent conditions. Initial construction details and history of post-construction works link the differences in pavement performance to pavement structure characteristics. 

In general, the flexible pavement structure consists of two characteristic sets of layers with different mechanical properties and performance the unbound or hydraulically bound aggregate layers, seated on the subgrade, and the bound asphalt (bituminous) layers, seated on the previous set of layers. 

Pavement evaluation and measurement of functional and structural characteristics... 

The most impressive section of the book to my mind, which is not covered in nearly as much depth in other texts, is the treatment of bituminous materials... in particular their characteristics, appropriate methods to characterize their performance in the laboratory, and means of building and maintaining a road using these materials. In addition, the book provides a comprehensive coverage of the constituent layers of a road pavement, the material properties of these layers, and associated laboratory tests required to characterize these. The different types of methods appropriate to structural design are covered nicely, as are methods of recycling and maintenance. ... 

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