Cannon TE-BBR, Инструкция по эксплуатации

Страница: 45 / 92

34 TE-BBR Instruction and Operation Manual
Beam Preparation
The method described in this section is essentially a description of current ASTM/AASHTO-approved
test methods for asphalt bending beam preparation. This manual procedure is not intended to
supersede the current methodology. Consult the appropriate method for specific test procedures.
Asphalt Beam Dimensions
The desired dimensions for the test beam are 127 mm (5") long, 12.7 mm (½”) wide and 6.35 mm
(¼”) thick.
Test Method
The Bending Beam Rheometer is designed to measure the low-temperature stiffness of asphalt
binders. Low temperature stiffness is significantly affected by the thermal history of the specimen.
Therefore, from the time the specimen is poured until the completion of the test, time intervals and
temperatures should be strictly controlled. Appropriate methodology must be followed precisely.
Failure to follow these guidelines can result in errors of 30 percent or more in the measured
stiffness.
Proper specimen preparation will produce test beams 6.35 ± .05 mm thick by 12.7 ± 0.05 mm wide
by 127 ± 0.5 mm long. Specimen preparation involves three major steps:
•
Mold preparation
•
Specimen pouring
•
Specimen demolding
When preparing the specimen, make sure to allow time for the TE-BBR bath to reach the test
temperature and stabilize. The bath should be equilibrated at the test temperature for at least 30
minutes before running the asphalt beam test.
Mold Preparation
A diagram of a specimen mold often used to prepare the test beam is shown in Figure 20. To
prepare the mold for filling, execute the following checklist:
1. Cover the inside surfaces of the metal bars with tacking material.