BS EN 14771:2012 pdf free.Bitumen and bituminousbinders – Determinationof the flexural creep stiffness-Bending BeamRheometer (BBR).
BS EN 14771 Spread a very thin layer of petroleum-based grease onto the interior faces of the dry and clean metal mouldsections. Press the plastic strips against the metal faces to force out any air bubbles.Cover the inside faces ofthe two end pieces with a thin film of de-moulding agent to prevent bituminous binder from sticking to themetal end pieces. Assemble the mould as shown in Figure 4 using O-rings to hold the pieces of the mouldtogether.Ensure plastic sheeting fits so that no raised edges occur on the cast beam.
NOTE1 Plastic sheeting 0,08 mm to 0,15 mm thick should be used. Transparency flm sold for use with laser printershas been found suitable for this purpose.
NOTE2 Polyvinyl alcohol and glycerol are found to be suitable as de-moulding agents. lt is recommended to avoidsilicone-based de-moulding agents that may affect the binder stiffness.
Pour hot binder into the metal mould that is at room temperature. Slightly overfill the mould. Pour the bindercontinuously toward the other end in a single pass. Let the filled mould cool in the ambient temperature for 45min to 60 min. After cooling to room temperature, trim the exposed face of the cooled specimen flush with thetop of the mould using a hot knife or a heated spatula.
Store all the test specimens in their moulds at the room temperature prior to testing. Testing shall becompleted within 4 h after specimens are poured.
NOTE1 lf the test is done at several temperatures, it may be practical to have longer times between pouring andtesting, which may effect the precision of the test.
Just prior to de-moulding, cool the mould containing the test specimen in a cold chamber or liquid bath for nolonger than 5 min in order to stiffen the test specimen so it can be readily de-moulded without distortion. In nocases shall the sample be exposed to a de-moulding temperature less than the test temperature.
At least two specimens per test temperature shall be tested.
NOTE2 Excessive cooling may cause unwanted hardening of the binder and affect the test result.
NOTE3During de-moulding, the specimen should be handled with care to prevent distortion. A warped test specimenmay affect the measured values.BS EN 14771 pdf download.