SHRP-A-379 traducir

NOTE 4.--Two BBR beams (requiring PAV material) are required at each test temperature. In addition,
four DT samples may also be needed at each test temperature. A minimum of two test temperatures wilI be
required.
6.10 Complete steps 6.1 through 6.9 during the first day of testing. This will allow
further testing to begin on the second day, when the PAV procedure is complete.
6.11 At the conclusior_ of the PAV procedure, carefully remove the residue from the
vessel and combine individual pans of the same aged asphalt binder. Prepare two bending
beam specimens for each test temperature according to TP1. Retain sufficient residue to
prepare four direct tension specimens for each test temperature if required.
6.12 Perform the DSR test (TP5) on the PAV residue. Begin at a test temperature
of 16°C for PG 52; 19°C for PG 58; 22°C for PG 64; and 28°C for PG 70, unless there is
other information to suggest the temperature at which G'sin 8 is < 5000 kPa. Decrease or
increase the test temperature at 3.0°C increments until the value for G'sin 8 exceeds
5000 kPa.
6.13 Determine the beginning test temperature for the BBR test (TP1) on the PAV
residue from table 1 of MP1. Use the starting PG determined in section 6.3 and the lowest
temperature from section 6.12 where the value for G'sin 8 did not exceed 5000 kPa, unless
there is other information to suggest the temperature at which the stiffness is < 300.0 MPa,
and the slope m is > 0.300.
6.14 Test pairs of BBR specimens according to TP1. Begin at the test temperature
selected in section 6.13 and increase at 6.0°C increments, until a stiffness and slope meeting
the requirements of MP1 are obtained. Test fresh BBR specimens at each temperature.
Determine the extent of physical hardening, report the creep stiffness (S) and the slope (m)
of the log creep stiffness versus log time relationship measured at 1 and 24 hours. Prepare
two sets each of two BBR specimens of original asphalt binder. Test one set after 1 hour of
conditioning and the second set after 24 hours of conditioning. The latter is conducted at
the lowest grading test temperature (Tmi_+ 10°C).
6.15 Certain asphalt binders may satisfy the MP1 slope requirement at substantially
lower temperatures than they satisfy the stiffness requirement. If the creep stiffness is
between 300 and 600 MPa at a test temperature at which the slope (m) is > 0.300, it may
be possible to satisfy the DT (TP3) failure strain requirement in lieu of the creep stiffness
requirement. Test four DT specimens according to TP3 at the test temperature at which m >
0.300, and determine if the failure strain is > 1.0%.
6.16 If the failure strain is < 1.0%, test additional sets of four DT specimens.
Increase the test temperature in 6.0°C increments until a failure strain > 1.0% is obtained.
Determine the test temperature at which m > 0.300 and the creep stiffness is < 300.0 MPa,
or, if the creep stiffness is between 300.0 and 600.0 MPa, the failure strain is > 1.0%.
6.17 Using the results of steps 6.12 through 6.16, determine the final grade of the
asphalt binder.
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