METHODS OF SAMPLING AXD TESTING HIGHWAY MATERIALS 83 
PREPARATION OF SAMPLE 
3. The sample shall be melted and stirred thoroughly, avoiding incorporating 
air babbles in the mass, and then poured into the ring so as to leave an e 
on cooling. The ring, while being filled, should rest on a brass plate which has 
been amalgamated to prevent the bituminous material from adhering to it. 
After cooling, the excess material shall be cut off cleanly with a slightly heated 
knife. 
PROCEDURE 
(A) BITUMINOUS MATERIALS HAVING SOFTENING POINTS 80' C. (176' F.) OR BELOW 
4. Fill the glass vessel to a depth of substantially 8.25 centimeters (3.25 
inches) with freshly boiled, distilled water at 5° C. (41° F.). Suspend the 
ring containing the sample in the water so that the lower surface of the filled 
ring is exactly 2.54 centimeters (1 inch) above the bottom of the glass vessel, 
and its upper surface is 5.08 centimeters (2 inches) below the surface of the 
water. Place the ball in the water but not on the specimen. Suspend the 
thermometer so that the bottom of the bulb is level with the bottom of the ring 
and within 0.635 centimeter (one-fourth inch) but not touching the ring. Main- 
tain the temperature of the water at 5° C. (41° F.) for 15 minutes. With 
suitable forceps place the ball in the center of the upper surface of the bitumen 
in the ring, thus completing the assembly as in Figure 33. 
Note. — TIip illustration shows only one ring, but more than one may be used at 
one time. 
5. Apply the heat in such a manner that the temperature of the water is 
raised 5° C. (9° F.) each minute. 
6. The temperature recorded by the thermometer at the instant the bituminous 
material touches the bottom of the glass vessel shall be reported as the softening 
point. No correction shall be made for emergent stem. 
7. The rate of rise of temperature shall be uniform and shall not be averaged 
over the period of the test. The maximum permissible variation for any minute 
period after the nrsr three shall be ±0.5° C. (0.9° F.). All tests in which the 
rate of rise in temperature exceeds these limits shall be rejected. 
(B) BITUMINOUS MATERIALS HAVING SOFTENING POINTS ABOVE 80° C. (176° F.) 
8. The same method as given under (A) shall be employed except that U, S 1'. 
glycerin shall be used instead of water, and the starting point of the glycerin 
bath shall be 32° C. (89.6° F.). The bath shall be brought to this temperature 
and thoroughly agitated, then the apparatus and specimens shall be placed in 
the bath, which shall be maintained under agitation at the starting temperature 
for 15 minutes, after which the assembly shall be completed by placing the ball 
on the center of the specimen and the test carried on as in (A). In applying 
the heat, the ring apparatus shall be placed off the center of the container and 
the burner placed midway between the center and edge of the beaker away 
from the specimen. 
The thermometer shall conform to the following requirements. These specifi- 
cations cover a special thermometer graduated in either centigrade or Fahren- 
heit degrees as specified, the ranges being 30° to 160° C. or 85° to 320° F., 
respectively. 
Type: Etched stem, glass. 
Liquid : Mercury. 
Ptange and subdivision: 30° to 160° C. in 0.5° C. or 85° to 320° F. in 1° F. 
Total length: 378 to 384 millimeters (14.88 to 15.12 inches). 
Stem : Plain front, enamel back, suitable thermometer tubing. Diameter, 
6 to 7 millimeters (0.24 to 0.28 inch). 
Bulb: Corning normal or equally suitable thermometric glass. Length. 9 
14 millimeters (0.35 to 0.55 inch). Diameter, 4.5 to 5.5 millimeters 
to 0.22 inch). 
Distance to 30° C. or 86° F. line from bottom of bulb: 75 to 90 millimeters 
(2.95 to 3.54 inches). 
Distance to 160° C. or 320° F. line from top of thermometer: 30 t< 4 T 
millimeters (1.18 to 1.77 inches). 
Expansion chamber : To permit heating the thermometer at least 50° C. 
(90° F.) above the highest temperature on the scale. 
