Three-Point Bending Cylinder (3PBC) Test System

Background:

According to a recent survey of state Departments of Transportation, many agencies consider fatigue cracking the most common type of asphalt failure that needs to be addressed. The same survey also indicated that a fatigue cracking test is not required in their asphalt mix design specifications. This is primarily because a simple, practical, and robust fatigue test is not available. Current asphalt fatigue cracking tests are lengthy, cumbersome, and expensive, due to extensive material requirements for sample preparation, difficulty in meeting air void targets, the large number of testing samples required, and excessive equipment costs. As a result, they are not practical alternatives for balanced and performance-based mix design approaches.

Technology Overview:

This technology is a cyclic three-point beam test setup in which the sample is a cylindrical asphalt specimen prepared using a gyratory compactor. Samples do not need to be cut, so a diamond saw is unnecessary. Nor are end-platens or gluing jigs needed. These features reduce equipment cost, the amount of test material needed, and test duration. Fatigue lives (Nf) at various strain levels, temperatures, and frequencies can be determined from a single test run at one strain level/temperature/frequency combination. These features will make this system a promising candidate as a routine testing method for fatigue characterization of asphalt mixes, either as part of a balanced mix design or mechanistic-empirical pavement structural design.

Advantages:

•    Simple (no cutting, gluing, etc.).
•    Practical for routine operation.
•    Low-cost.
•    Can be easily performed in Asphalt Mixture Performance Tester (AMPT) or any other testing frame with dynamic loading potential.

Applications:

The primary application for this technology is asphalt fatigue cracking testing.

Intellectual Property Summary:

Know-how based

Stage of Development:

TRL 3 - Experimental proof of concept

Licensing Status:

This technology is available for licensing.

Licensing Potential:

This technology would be of interest to anyone involved in asphalt fatigue characterization, including:
•    State and Federal Departments of Transportation.
•    Local highway departments.
•    Asphalt contractors.
•    Equipment manufacturers.