SHRP-A-379 traducir

10.2 Anneal the asphalt binder for the test specimen by heating until it is sufficiently
fluid to pour. Annealing prior to testing removes reversible molecular associations (steric
hardening) that occur during normal storage at ambient temperature.
NOTE6.--Minimum pouring temperatures that produce a consistency equivalent to that of SAE 10W30
motor oil (readily pours but not overly fluid) at room temperature are recommended. The specific temperature will
depend on the grade of binder and its prior aging history, if any. Temperatures less than 135°C are desirable.
Temperatures above 135°C may be required, however, for some modified asphalt binders or heavily aged binders.
10.3 Place the plastic end inserts into both ends of the mold. Place the molds and
inserts into a 163°C oven for 30 minutes.
10.4 After heating, place the mold on a 6- to 7-mm-thick aluminum plate. Do not
preheat the aluminum plate. Pour hot asphalt binder into the mold by starting at one end of
the mold and moving across the mold in a single pass. Pour the specimen in a continuous
stream to avoid entraining air bubbles or gaps. Complete the pouring operation as quickly as
possible to avoid any excessive drop in the temperature of the asphalt binder. Stop pouring
when the asphalt is slightly above the top surface of the mold.
10.5 After pouring the test specimen, allow the entire assembly to cool on the
benchtop at ambient temperature for approximately one hour. Do not quench the specimen to
achieve ambient temperature.
10.6 As soon as the specimen has cooled to room temperature, trim off the excess
asphalt binder with a straight cutting edge (e.g., a flat cheese cutter or spatula) so that the
asphalt binder is flush with the top of the mold. Use care during the trimming operation so
that the asphalt binder is not pulled away from the mold and that the bond between the
plastic inserts and the asphalt binder is not damaged. Trim the specimen in a consistent
manner. Pull the cutting edge along the long axis of the sample flush with the surface of the
mold to remove the excess asphalt binder. After trimming, remove all debris or extraneous
asphalt binder from the holes or slots in the plastic insert.
NOTE7.--Caution:
occurs, discard the sample.
Excessive downward pressure during trimming will distort the sample mold. If this
10.7 Immediately prior to demolding, place the mold containing the specimen in a
freezer at -5 + 5 °C until the specimen is sufficiently stiff to demold without distorting the
sample. Some softer grades may require lower temperatures. Time in the freezer should not
exceed 15 minutes. After demolding, place the sample on the specimen storage plate (see
section 6.4). Measurement of specimen dimensions after demolding is not necessary since
dimensional tolerances are closely controlled in the molding process.
11. PROCEDURE
11.1 Set the environmental chamber at the desired testing temperature and wait until it
stabilizes to within + 0.2°C-of the desired test temperature. When testing for compliance
with MP1, use the test temperatures specified in table 1 of MP1.
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