General. 
Physical and 
chemical prop- 
erties. 
Methods of test- 
ing. 
TP-6. REFINED TAR FOR CONSTRUCTION. 
The refined tar shall be homogeneous and free from water. 
It shall meet the following requirements : 
1. Specific gravity 25°/25° C. (77°/77° F.) 1.200 to 1.250 
2. Float test at 50° C. (122° F.) 150 sec. to 180 sec. 
3. Total distillate by weight: 
To 170° C. (338° F.) not more than 1.0 per cent 
To 270° C. (518° F.) not more than 10.0 per cent 
To 300° C, (572° F.) __not more than 20.0 per cent 
a. Melting point of residue, 
not more than 65° C. (149° F.) 
4. Total bitumen (soluble in carbon disulphide)__80% to 97% 
Tests of the physical and chemical properties of the refined tar 
shall be made in accordance with the following methods : 
1. Specific gravity, U. S. Department of Agriculture Bulletin 
314, p. 5. 
2. Float test, XL S. Department of Agriculture Bulletin 314, 
p. 9. 
3. Distillation test, A. S. T. M. Standard Test D 20-16. 
a. Melting point, A. S. T. M. Tentative Standard D 
36-16 T, Proc. A. S. T. M. 1916, p. 549. 
4. Total bitumen, U. S. Department of Agriculture Bulletin 
314, p. 25. 
This specification provides for a material to be used in the con- 
struction of bituminous macadam or one-size stone bituminous 
concrete in the southern United States. It is intended to cover 
refined gas-house or coke-oven tar. 
In bituminous-macadam construction it should be applied in the 
manner outlined under Specification TP-2. 
In one size stone bituminous-concrete construction it should be 
used in the manner outlined under Specification TP-4. 
In either type of construction the tar should be heated to from 
250° F. to 300° F. Roads of this character may be maintained 
with tar surface treatments, using the materials and methods 
given under Specifications TC-1. TC-2, or TH-1. Such mainte- 
nance treatments should be applied whenever the wear comes di- 
rectly upon the wearing-course rock. 
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