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Last Updated: Jun 20, 2017
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ASTM D7227/D7227M-11e1
Standard Practice for Rapid Drying of Compacted Asphalt Specimens Using Vacuum Drying Apparatus
Standard Practice for Rapid Drying of Compacted Asphalt Specimens Using Vacuum Drying Apparatus
D7227_D7227M-11E01
ASTM|D7227_D7227M-11E01|en-US
Standard Practice for Rapid Drying of Compacted Asphalt Specimens Using Vacuum Drying Apparatus
Standard
D7227/D7227M Standard Practice for Rapid Drying of Compacted Asphalt Specimens Using Vacuum Drying Apparatus>
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Significance and Use
3.1 Specimen dry weight is a critical measure in determination of accurate density and many other tests in the construction and raw materials industries. Drying specimens at room temperature is required for some tests and provides an advantage for other tests to ensure the integrity and to preserve the characteristics of specimens.
3.2 This practice covers drying compacted asphalt specimens in a vacuum chamber that is capable of keeping the specimen at close to room temperature. A vacuum pump reduces the pressure inside the chamber, thus allowing water to evaporate at low temperature. Since the specimen naturally cools during the evaporation process, making water harder to evaporate, it is important to have proper temperature controls in the chamber to ensure specimen remains at close to room temperature. Automatic controls within the unit allow the specimen to remain at close to room temperature by periodically allowing a flow of warm air to enter the vacuum chamber. Cycling between vacuum and airflow conditions allows the specimen to dry in a short period of time. Completely saturated specimens with over 30 g [0.07 lb] of retained water can be dried in about 30 minutes. For most field cores that are not completely saturated the drying time is generally less than 15 minutes.
Note 1—Cycle time (period) can depend on the material composition. Each cycle involves an alternating period of 30 to 180 seconds of vacuum operation and 30 to 120 seconds of air flow.
3.3 This method can be used for 100 mm [4 in.] diameter, 150 mm [6 in.] diameter cylindrical, and cubical compacted bituminous specimens.
Scope
1.1 This practice covers the process of drying compacted asphalt specimens using vacuum drying apparatus.
1.2 The specimens dried by this practice remain at room temperature, which helps in maintaining specimen integrity during the drying process.
1.3 This practice can be used for compacted cylindrical and cubical bituminous laboratory and field specimens
1.4 This practice can also be used for drying other construction materials such as concrete, soils, aggregates and loose asphalt mixtures. Use manufacturers recommendations for drying other construction materials.
1.5 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalent; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.