SPECIFICATIONS FOR BITUMINOUS ROAD MATERIALS. 55 
beaker containing approximately 400 cc. of water at a temperature of 5° C. 
(41° F.). Arrange the thermometer bulb within | inch of the sample and at 
the same level. Apply heat uniformly over bottom of the beaker in quantity 
sufficient to raise the temperature 5° C. (9° F.) per minute. Record the tem- 
perature at starting the test and every minute thereafter until the test is 
completed. The rate of heating is very important. The softening point is the 
temperature at which the specimen has dropped 1 inch. Successive tests should 
average within 3° C. For temperatures above 90° C, glycerin shall be used 
instead of water. 
PENETRATION. 
[A. S. T. M. Standard Test D5-16.] 
I. DEFINITION. 
1. Penetration. — Penetration is defined as the consistency of a bituminous 
material expressed as the distance that a standard needle vertically penetrates 
a sample of the material under known conditions of loading, time and tem- 
perature. Where the conditions of test are not specifically mentioned, the 
load, time and temperature are understood to be 100 g., 5 seconds, 25° C. (77° 
F.), respectively, and the units of penetration to indicate hundredths of a 
centimeter. 
II. APPARATUS. 
2. Container. — The container for holding the material to be tested shall be a 
flat-bottom, cylindrical dish, 55 mm. (2 3/16 inches) in diameter and 35 mm. 
(If inches) deep. 1 
3. Needle. — The needle 2 for this test shall be of cylindrical steel rod 50.8 mm. 
(2 inches) long and having a diameter of 1.016 mm. (0.04 inches) and turned 
on one end to a sharp point having a taper of 6.35 mm. (J inch). 
4. Water oath. — The water bath shall be maintained at a temperature not 
varying more than 0.1° C. from 25° C. (77° F.). The volume of water shall 
be not less than 10 liters and the sample shall be immersed to a depth of not 
less than 10 cm. (4 inches) and shall be supported on a perforated shelf not 
less than 5 cm. (2 inches) from the bottom of the bath. 
5. Apparatus for penetration. — Any apparatus which will allow the needle to 
penetrate without appreciable friction, and which is accurately calibrated to 
yield results in accordance with the definition of penetration, will be acceptable. 
6. Transfer dish for container. — The transfer dish for container shall be a 
small dish or tray of such capacity as will insure complete immersion of the 
container during the test. It shall be provided with some means which will 
insure a firm bearing and prevent rocking the container. 
III. PREPARATION OF SAMPLE. 
7. Preparation of sample. — The sample shall be completely melted at the 
lowest possible temperature and stirred thoroughly until it is homogeneous and 
free from air bubbles. It shall then be poured into the sample container to a 
depth of not less than 15 mm. (f inch). The sample shall be protected from 
dust and allowed to cool -in an atmosphere not lower than 18° C. (65° F.) for 
one hour. It shall then be placed in the water bath along with the transfer 
dish and allowed to remain one hour. 
1 This requirement is fulfilled by the American Can .Co.'s gill style ointment box, 
deep pattern, 3-ounce capacity. 
^Journal of Agricultural Research, Vol. V, No. 24, pp. 1125-1126. 
