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Abstract

The moisture susceptibility material testing apparatus includes a specimen chuck, multiple rollers, a temperature controlled water bath, and a control system to automate the testing cycle and collection of data. The water bath is prepared at the desired testing temperature. A material specimen, such as a cylindrical hot mix asphalt (HMA) material specimen, is placed within the water bath on multiple rollers and a specimen chuck then clamps the specimen with an adjustable force. A first and second roller are positioned about the exterior circumference of the cylindrical specimen and a predetermined force is applied radially to the specimen through a third roller. The specimen is rotated about its cylindrical axis, driven by the rotation of the rollers and specimen chuck. A displacement sensor monitors the position of the third roller, yielding a measurement of the rut depth on the material specimen. The number of revolutions the specimen experiences while the force is applied and the rut depth are recorded during the test. Test temperature and rotational velocity are also recorded. Once the third roller has reached a specified displacement (rut depth), or a specified number of force repetitions have occurred, the test is complete. The roller displacement (rut depth) vs. the number of force repetitions is graphed. Test temperature and rotational velocity are also recorded. The resulting data yields information on the effect of moisture on the durability of the HMA product. If desired for comparison purposes, the test may be repeated dry within a temperature-controlled chamber. The apparatus and method may also be used to evaluate rutting and fatigue failure mechanisms in cylindrical material specimens.

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