NA-6. FLUXED BERMUDEZ ASPHALT FOR CONSTRUCTION. 



The fluxed native asphalt shall be homogeneous, free from gengj-ai, 

 water, and shall not foam when heated to 175° C. (347° F.). 



It shall meet the following requirements: Physical and 



1. Specific gravity 25°/25° C. (77°/77° P.) 1.050 to 1.070 ^^^'i^^'f*^ ^''"*" 



2. Flash point not less than 175° C. (347° F.) 



3. Melting point 45° C. (113° F.) to 55° C. (131° F.) 



4. Penetration at 25° C. (77° F.)., 100 g., 5 sec 50 to 60 



5. Loss at 163° C. (325° F.), 5 hours not more than 3.0% 



a. Penetration of residue at 25° C. (77° F.), 100 g., 

 5 sec - not less than 25 



6. Total bitumen (soluble in carbon disulphide), not less 



than 94.0%. 



b. Inorganic matter insoluble 2.5% to 4.0% 



Tests of the physical and chemical properties of the fluxed Methods of test- 

 native asphalt shall be made in accordance with the following 

 methods : 



1. Specific gravity, U. S. Department of Agriculture Bulletin 



314, p. 5. 



2. Flash point (open cup), U. S. Department of Agriculture 



Bulletin 314, p. 17. 



3. Melting point, A. S. T. M. Tentative Standard D 36-16 T. 



Proc. A. S. T. M. 1916, p. 549, 



4. Penetration, A. S. T. M. Standard Test D 5-16. 



5. Volatilization test, U. S. Department of Agriculture Bul- 



letin 314, p. 19, using 50-gram sample. 



6. Total bitumen, U. S. Department of Agriculture Bulletin 



314, p. 25. 



This specification provides for a material to be used in the 

 construction of graded fine aggregate bituminous concrete in the 

 southern United States or for sheet asphalt construction in the 

 northern United States. It is intended to cover satisfactory 

 grades of products prepared by fluxing Bermudez asphalt. 



In fine aggregate bituminous concrete construction it should 

 be used in the manner outlined under Specification NA-5. 



Sheet asphalt construction contemplates a mixture of the 

 fluxed asphalt with properly graded sand and a mineral filler. 

 The bituminous material and sand should be heated separately to 

 a temperature of from 275° F. to 325° F. The filler should be 

 added to the hot sand and followed by the asphalt. The mixture 

 should contain from 9 to 12 per cent bitumen and will vary 

 within these limits with the exact grading of the aggregate. 

 After thorough mixing the hot mixture should be deposited in 

 a uniform layer on a binder course which has been previously 

 laid over a concrete base. It should be laid to such depth that it 

 will yield a uniform layer li or 2 inches in thickness as may be 

 required after thorough rolling. 



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