NA-7. FLUXED BERMUDEZ ASPHALT FOR CONSTRUCTION. 



General. 



Physical and 

 chemical prop- 

 erties. 



Methods of test- 

 ing. 



The fluxed native asphalt shall be homogeneous, free from 

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

 It shall meet the following requirements : 



1. Specific gravity 25°/25° C. (77°/77° F.) 1.055 to 1.075 



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 40 to 50 



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 20 



6. Total bitumen (soluble in carbon disulphide), 



not less than 94.0% 



6. Inorganic matter insoluble 2.5% to 4.0% 



Tests of the physical and chemical properties of the fluxed 

 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 Bulle- 



tin 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 southern United States or for the 

 same type of construction in the northern United States to with- 

 stand, very heavy traffic. It is intended to cover satisfactory 

 grades of products prepared by fluxing Bermudez asphalt. 



Sheet asphalt construction contemplates a mixture of the fluxed 

 asphalt with properly graded sand and a mineral filler. The 

 asphalt 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 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 li or 2 inches in thickness as may be required after 

 thorough rolling. 



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