(3) Aggregate Gradations and Fractions . For the purpose of speci- 

 fications and test reporting it is almost universal practice to specify the 

 gradation of aggregates on the basis of the total aggregate gradation, 

 i.e., total percent by weight passing the designated sieve sizes. The 

 individual fractions of the total aggregate gradation, however, are desig- 

 nated as follows: 



(a) Coarse aggregate (retained No. 8 sieve); 



(b) fine aggregate (passing No. 8 sieve); and 



(c) mineral dust (passing No. 200 sieve). 



It is also important to note that the aggregate gradations as well as the 

 individual fractions are specified independently of the total mix; i.e., 

 the total aggregate equals 100 percent. 



Aggregate materials often are identified in broader terms as: rock, 

 sand, and filler. These terms usually are applied to the stockpiled 

 materials supplied to the job site. The following definitions appear to 

 have the greatest usage: 



(a) Rock: material that is predominantly coarse aggregate 

 (retained No. 8) ; 



(b) sand: material that is predominantly fine aggregate (passing 

 No. 8); and 



(c) filler: material that is predominantly mineral dust (passing 

 No. 200). 



d. Functions in Coastal Structures . 



(1) General . Asphalt has many properties that make it particularly 

 suitable for use in hydraulic structures. It is versatile in form and 

 application. Asphalt can be used alone (as in an asphalt membrane), or it 

 can be mixed with other materials producing mixes for a variety of purposes. 

 It can be combined with graded aggregate to form a voidless and impermeable 

 mix, or it can be combined with an open-graded aggregate to form a porous 

 mixture allowing free passage of water. 



There are many types of asphaltic materials used in hydraulic applica- 

 tions. Each type can be classified in one of the following distinct 

 categories: 



(a) Impermeable asphalt mixes, 



(b) porous asphalt mixes, 



(c) asphalt mastics, 



(d) asphalt cement, and 



(e) prefabricated asphalt materials. 



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