AASHTO T 240:2021 Standard Method of Test for Effect of Heat and Airon a Moving Film of Asphalt Binder (Rolling Thin-Film Oven Test).
SIGNIFICANCE AND USE
This method indicates the approximate change in properties of asphalt binder during conventional batch plant and drum mix plant mixing at about 150°C (302°F) as indicated by viscosity and other rheological measurements. The residue from this test is also used to determine the conformance of an asphalt binder to M 320. It yields a residue that approximates the condition of the asphalt binder immediately after the pavement is constructed. If the mixing temperature differs appreciably from 150°C (302°F). more or less effect on the properties will occur. This method can also be used to determine mass change, which is a measure of asphalt binder volatility and mass changes resulting from oxidation.
Oven—A double-walled electrically heated convection type with inside dimensions as follows: a height of 381 mm (15 in.), a width of 483 mm (19 in.). and a depth (with door closed) of 445 ± 13 mm (1 7/2 ± 1/2 in.). The door shall contain a symmetrically located window with dimensions of 305- to 330-mm (12- to 1 3-in.) wide by 203- to 229-mm (8- to 9-in.) high. The window shall contain two sheets of heat-resistant glass separated by an air space. The window should permit an unobstructed view of the interior of the oven. The heating element shall be located below the oven floor and shall be adequate to maintain the required temperature. The oven shall be vented at the top and bottom. The bottom vents shall be located symmetrically to supply incoming air around the heating elements. They shall have an open area of 15.0 ± 0.7 cm2 (2.31 ± 0.11 in.2). The top vents shall be symmetrically arranged in the upper part of the oven and have an open area of 9.3 ± 0.45 cm2 (1.45 ± 0.07 in.2).
5.1.1. The oven shall have an air plenum covering the side walls and ceiling, the air space being 38.1 ± 4.8 mm (1 V2 ± /16 in.) deep from the walls and ceiling. At a midpoint in the width of the oven and 152 mm (6 in.) from the face of the circular metal carriage to its axis, a squirrel cage-type fan 133.4 mm (5V4 in.) outside diameter by 73 mm (27f in.) wide shall be turned at 1725 r/min by an externally mounted motor. The squirrel cage fan shall be set so that the fan turns in an opposite direction to its vanes. The air flow characteristics of the fan-plenum system shall be suctioned from the floor of the oven through the wall plenums with the air exiting through the fan. Figures 1 and 2 show details of this fan-plenum system. AASHTO T 240 pdf download.