Humboldt H-1068 Series Ductility Testing Machines User Manual

Page 4

Sample Preparation
Unless otherwise speciﬁed the test should be conducted at a temperature

of 77°F ± 0.9°F (25°C ± 0.5°C), and a speed of 5 cm per minute ± 5.0 percent.

When a low-temperature ductility test is desired, the test should be run at a

temperature of 39.2°F (4°C), and at a rate of pull of 1 cm per minute.

Assemble the mold on the brass plate. To prevent the material under test from

sticking, it is suggested that the surface of the plate and interior surfaces of the

sides of the mold be thoroughly amalgamated. Make sure the plate is perfectly

flat and level so that the bottom surface of the mold will touch it throughout.

Completely melt the bituminous material to be tested until thoroughly fluid by

heating it in an oil bath maintained at the minimum temperature needed to

properly liquefy the sample, when paving asphalt cements are to be tested,

the oil bath should be maintained at a temperature of 302°F to 320°F (150°C

to 160°C).

Strain the melted sample through a No. 50 sieve. After stirring thoroughly,

pour into the mold, taking care not to disarrange the parts of the mold. Pour

the material back and forth in a thin stream from end to end of the mold until

the mold is more than level full.

Allow the mold containing the material to cool to room temperature for a

period of 30 to 40 minutes. Then place the mold in the water bath maintained

at the speciﬁed temperature of test for 30 minutes. Cut off the excess bitumen

with a hot, straight-edged knife or spatula to make the mold level full.

Place the brass plate and mold with the briquette specimen in the water bath

and keep them at the speciﬁed temperature for a period of from 85 to 95

minutes. After the elapsed period of time, remove the briquette from the plate,

detach the side pieces and immediately test the briquette.

Test Procedure
Fill the 20 gallon capacity trough with water until the level reaches a point

where it will cover the test specimen by at least 2.5 cm both above and below.

Bring the water to the desired test temperature. During the test the water

should be kept at the speciﬁed temperature within ±0.9°F (±0.5°C).

To adjust the speed of the carriage, move the knurled knob at the end of the

sliding gear all the way in for 1/4 cm per minute, half way out for 1 cm per

minute and all the way out for 5 cm per minute. Be sure to locate the

positioning lever in the proper slot. This will not only locate, but will also lock

the gears in their exact alignment.