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Bending Beam Rheometer

Instrument Details

Wykeham Farrance BBR test apparatus.
The BBR test is used to determine an asphalt binder’s creep stiffness as a function of time.



Bending Beam RheometerBending Beam Rheometer

Working Principles

The Bending Beam Rheometer (BBR) test (see Figure 1) provides a measure of low temperature stiffness and relaxation properties of asphalt binders. These parameters give an indication of an asphalt binder’s ability to resist low temperature cracking.
The basic BBR test uses a small asphalt beam that is simply supported (Figure 2) and immersed in a cold liquid bath. A load is applied to the center of the beam and its deflection is measured against time. Stiffness is calculated based on measured deflection and standard beam properties and a measure of how the asphalt binder relaxes the load induced stresses is also measured. BBR tests are conducted on PAV aged asphalt binder samples. It is a software-controlled test.


User Instructions

  1. A sample of asphalt binder is molded into a beam measuring 6.25 x 12.5 x 127 mm. This sample is then simply supported at two points 102 mm apart in a controlled temperature fluid bath. The beam is then loaded at the midpoint by a 100 g load that, under normal gravity conditions, produces 0.98 N of force. The beam deflection is measured at 8, 15, 30, 60, 120 and 240 seconds. Beam stiffness, often called “creep stiffness”, is calculated for these times. A stiffness master curve is then fitted to these points. The BBR test is done on two beam samples.

Contact Details

CSIR-Central Road Research Institute,
Delhi-Mathura Road, New Delhi-110025
Phone: 011-26832173, 26832325
Email: director [dot] crri [at] nic [dot] in

Instrument Usage Charges(Including GST)

IndustryUniversities/IITsNational LabsRs 75000/- per sampleRs 25000/sampleRs 25000/sample