AASHTO PP 104-20 pdf free download

AASHTO PP 104-20 pdf free download.Sample Preparation and Polishing of Asphalt Mixture Specimens for Dynamic Friction Testing.
TERMINOLOGY
initialfriction value—Initial friction measurement on the asphalt mixture test specimens before they are polished in the TWPD.
4.2. terminal friction value—Friction measurement on the asphalt mixture test specimens at the point at which additional cycles of polishing in the TWPD will have negligible effects on the resulting friction value of the surface.
APPARATUS
Sample Compaction Device—A machine capable of uniformly compacting an asphalt mixture within a rigid mold to a specified height to achieve a specified density. This may be accomplished using linear kneading compaction, plate compaction, or manual impact compaction.
5.2. Specimen Mold—A rigid specimen mold with dimensions that permit the compaction of a 508 x
508 mm (20 x 20 in.) asphalt mixture slab specimen. In some cases, a dynamic friction tester (DFT) will accommodate a smaller sample, in which case, the resulting compacted asphalt mixture slab specimen shall be no less than 400 mm (16 in.) wide.
5.3. Non-Stick Paper—Paper or other material that does not readily adhere to an asphalt mixture.
5.4. Metal Partition—For full-scale slab specimens, a metal partition capable of dividing the asphalt mixture into four quadrants.
5.5. Transf’r Funnel—A metal device with a tapered end capable of transferring an asphalt mixture from pans into the four quadrants created by the splitter.
5.6. Thermometers—Armored, glass, or dial type thermometers with metal stems for determining the temperature of aggregates, binder, and asphalt mixtures Lip to 204°C (400°F) and readable to 2°C (5°F).
5.7. Balance—A balance meeting the requirements of M 231, Class G 5, for determining the mass of aggregates, binder, and asphalt mixtures.
5.8. Oven—An oven thermostatically controlled to ± 3°C (5°F), for heating aggregates, binder, asphalt mixtures, and equipment as required. The oven shall be capable of maintaining the temperature required for asphalt mixture conditioning in accordance with R 30.
5.9. Three-Wheel Polishing Device (TWPD)—A polishing device that has three patterned pneumatic tires and is capable of exerting 0.65 ± 0.02 kN (146 ± 5 lbs) through the tires to the test surfaces. The device’s height shall be adjustable to accommodate sample heights of 25 mm (1.0 in.) to 50 mm (2.0 in.).
5.9.1. The tire size shall be 2.80/2.50-4 and shall maintain a pressure of 240 ± 34 kPa (35 ± 5 psi) and a tread depth of no less than 2 mm (0.1 in.). The tire tread shall have a ribbed pattern. The tire tread shall be free of any visible contamination. When replacement is necessary, all tires shall be replaced at the same time with tires having the same tread pattern as the tires being replaced.
5.9.2. The polishing machine shall be equipped with a water system to wash off abraded rubber particles. The water will be applied uniformly across the surface of the specimen such that any dislodged material is flushed away.
5.9.3. The driving mechanism for the vertical shaft shall be an electric motor geared to rotate the shaft and wheel assembly at a speed of 6.28 radians per second (60 ± 5 revolutions per minute). Note 1—The path of polishing should coincide with the direction of friction testing.
5.9.4. The machine shall be equipped with an automatic counter that can shut off the machine at a predetermined number of revolutions.
5.9.5. Dynamic Friction Tester DFT,)—A device used to measure pavement surface friction values as is described in ASTM E191 1.AASHTO PP 104-20 pdf download.