NA-8. FLUXED TRINIDAD ASPHALT FOR CONSTRUCTION. 



The fluxed native asphalt shall be homogeneous, free from General. 

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



It shall meet the following requirements: Physical and 



1. Specific gravity 25V25° C. (77V77° F.) 1.200 to 1.250 ^J^/^'f"^ P'""" 



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 68.0% 



b. Inorganic matter insoluble 20.0% to 30.0% 



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 for sheet 

 asphalt construction in the northern United States. It is in- 

 tended to cover satisfactory grades of products prepared by flux- 

 ing Trinidad asphalt. 



Sheet asphalt construction contemplates a mixture of the fluxed 

 asphalt with properly graded sand and a mineral flller. The 

 asphalt and sand should be heated separately to a temperture 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 per cent 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 IJ or 2 inches in thickness as may be required after thor- 

 ough rolling. 



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