AASHTO T 179:05(2013) Standard Method o f Test for Effect of Heat and Air on Asphalt Materials (Thin-Film Oven Test).
4.1. This method indicates approximate change in properties of asphalt during conventional hot-mixing at about 150°C (300°F) as indicated by viscosity, penetration, or ductility measurements. It yields a residue that approximates the asphalt condition as incorporated in the pavement. If the mixing temperature differs appreciably from the 150°C (300° F) level, more or less effect on properties will occur.
5.1. Oven—The oven shall be electrically heated and shall conform to the performance requirements of ASTM E145, for Gravity-Convection and Forced-Ventilation Ovens Type lB (GravityConvection), for operating temperatures up to 180°C (356°F). During the tests for compliance to ASTM E 145 requirements, the oven shelf, properly centered as described in Section 5.1.2, shall be in place and rotating.
5.1.1. construction —The oven shall be rectangular with minimum interior dimensions (exclusive of space occupied by the heating element) of 330 mm (13 in.) in each direction. (See Note 1.) The oven shall have, in front, a tightly fitted hinged door, which shall provide a clear opening substantially the same as the interior height and width of the oven. The door may contain a window with dimensions of at least 100 by 100 mm (4 by 4 in.) and with two sheets of glass separated by an air space. through which a vertical thermometer, located as specified in Section 5.2, may be read without opening the door; or the oven may be provided with an inner glass door, through which the thermometer may be observed on opening the outer door momentarily. The oven shall be adequately ventilated by convection currents of air and for this purpose shall be provided with openings for the entrance of air and for the exit of heated air and vapors. Openings may be of any size and arrangement provided the requirements of ASTM E145, Type 1 B are met.
5.1.2. Rowling Shelf—The oven shall be provided with a metal circular shelf having a minimum diameter of 250 mm (9.8 in.) (Note 1). The shelf construction shall be such that it provides a flat surface for support of the containers without blocking all air circulation through the shelf when the containers are in place. The shelf shall be suspended by a vertical shaft and centered with respect to the horizontal interior dimensions of the oven and shall be provided with a mechanical means of rotating it at the rate of 5.5 ± 1.0 r/min. The shelf shall be vertically located as close to the center of the oven as permitted by compliance with the requirements of Section 5.2 regarding thermometer placement. The shelf shall be constructed or marked in such a way that the sample containers can be placed in the same position during each test. There shall be a minimum of two and a maximum of six sample container positions. Each sample container position shall be symmetrical with respect to the shaft and to any holes in the shelf The number of sample container positions shall be the maximum that will fit on the shelf without violating the above requirements and without excessive overhang.
Note I —Minimum size ovens accommodate two containers. For routine or control operations, larger ovens, having proportionately larger shelves to accommodate a greater number of containers, may be advantageous and are suitable, provided the requirements of ASTM E145, Type I B are met. Under no circumstances should more than one shelf, properly centered, be used in an oven.AASHTO T 179 pdf download.