OA-7. OIL ASPHALT FOR CONSTRUCTION. 



The oil asphalt shall be homogeneous, free from water, and GeneraL 

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

 It shall meet the following requirements : Physical and 



chemical prop- 



1. Specific gravity 2o°/25° C. (77°/77° F.)__not less than 1.020 erties. 



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



3. Melting point 45° C. (113° F.) to 65° C. (149° 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 1.0% 



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 99.5% 

 a. Organic matter insoluble not more than 0.2% 



Note. — Material for any one contract shall not vary more than 0.020 

 in specific gravity nor more than 10° C. in melting point within the test 

 limits above specified. 



Tests of the physical and chemical properties of the oil asphalt Methods of test- 

 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, 



Proceedings 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 oil asphalts prepared from Mexican, California, Texas, 

 and other petroleums. 



Sheet asphalt construction contemplates a mixture of the oil 

 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 bo required after thorough 

 rolling. 



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