MIL-DTL-82604A (OS)
4.5.1.5 Ash. Transfer a weighed portion of approximately 1 g of the sample to a tared
porcelain or platinum crucible and place in a cold muffle furnace having good air circulation and
capable of temperature regulation between 700 and 750 ºC. Gradually raise the temperature of
the furnace to a red heat. Finish the ignition to constant weight at a temperature between
700 and 750 ºC. Cool in a desiccator and weigh. Calculate the weight of residue as percent
ash in the sample.
4.5.2 Test sample preparation. The material for all of the tests required by paragraphs
3.2.2 through 3.3.4 shall be prepared at the same time and from the same melt of the test
sample selected in accordance with 4.3.2 as follows.
4.5.2.1 Apparatus.
a. Sample container - Stainless steel, 1-liter (l) beaker approximately 4⅛ inches I.D. by
5¾ inches high, straight sides, no pouring lip.
b. Oven - Electric, mechanical convection type, temperature range: ambient to 250 ºC.
c. Stirring rod - 5/16-inch diameter, 12 inches long, Teflon with a steel core.
4.5.2.2 Preconditioning. Transfer a 600 to 650-g sample of the asphaltic compound
selected in 4.2 to a 1-l stainless steel beaker. Heat the sample in an oven, mechanical
convection type, for 3¾ hours. Set the temperature of the oven to 232 ± 2 ºC. When the oven
is at the desired temperature, place the sample in the center of the oven with good air
circulation on all sides. Hand-stir the sample with the Teflon stirring rod every 30 minutes to
prevent lumping. At the end of the heating period, remove the sample from the oven for the
Zahn viscosity test of 4.5.3. When this test is completed, return the sample and its container to
the same oven and heat for an additional 30 minutes. Do not allow the sample to remain out of
the oven for viscosity testing for longer than 2 minutes. At the end of the second heating period,
pour the samples and coat steel panels for the tests of 4.5.4, 4.5.5, 4.5.6, 4.5.7, 4.5.8, 4.5.9,
and 4.5.10.
4.5.3 Viscosity. Determine the viscosity of the asphaltic compound with a Zahn
viscosimeter, No. 5 cup, at the end of the 3¾ hours of heating at 232 ± 2 ºC. Preheat the
viscosimeter in the same oven and at the same time as the sample is being prepared. Remove
the sample beaker containing the molten compound and the viscosimeter from the oven. Hold
the viscosimeter in a vertical position and immediately dip it into the sample completely filling
the cup. Lift the cup ½-inch above the top surface of the beaker and allow the asphaltic
compound to drain into the beaker. With a stopwatch, record the time in seconds between
when the cup breaks the surface of the sample and when the steady flow of the liquid from the
orifice suddenly stops.
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