AASHTO TP 125-16 (2020) PDF Download

The AASHTO TP 125-16 (2020) standard is a provisional method for determining the flexural creep stiffness of asphalt mixtures using the Bending Beam Rheometer (BBR). This method is designed to measure the deformation or creep of an asphalt specimen under flexural loading.

The standard provides guidelines for preparing the test specimens, including the size and shape of the specimens. It specifies that the specimens should have a nominal maximum aggregate size (NMAS) of 19 mm or less. The standard allows for the use of both laboratory compacted specimens and field core specimens.

In the test procedure, a vertical notch is cut on the test specimen, which is a half disc with a notch parallel to the loading and vertical axis of the semicircular disc. The specimen is then subjected to flexural loading using the BBR, and the creep deformation is measured over a specified time period.

The standard also includes procedures for calculating other relevant parameters derived from the load-displacement curve, which can be used to assess the damage resistance of the asphalt mixture. These parameters, along with field performance data, can be used to develop a Flexibility Index (FI) for predicting the asphalt mixture's performance and suitability for use.