ASTM D7227-06
(Practice)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
SIGNIFICANCE AND USE
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.
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 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.
This method can be used for 100 mm diameter, 150 mm diameter cylindrical, and cubical compacted bituminous specimens.
This method can also be used for drying loose asphalt mixtures, aggregate samples and other solid specimens. Follow manufacturers recommended procedures for drying specimens other than compacted bituminous specimens.
This method can be used to determine moisture content and amount of water loss during drying by weighing the sample before and after the drying operations.
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 SI units are to be regarded as the standard.
This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory requirements prior to use.
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Standards Content (Sample)
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Designation:D7227–06
Standard Practice for
Rapid Drying of Compacted Asphalt Specimens Using
Vacuum Drying Apparatus
This standard is issued under the fixed designation D7227; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3.2 This practice covers drying compacted asphalt speci-
mens in a vacuum chamber that is capable of keeping the
1.1 This practice covers the process of drying compacted
specimen at close to room temperature. A vacuum pump
asphalt specimens using vacuum drying apparatus.
reduces the pressure inside the chamber, thus allowing water to
1.2 The specimens dried by this practice remain at room
evaporate at low temperature. Since the specimen naturally
temperature, which helps in maintaining specimen integrity
cools during the evaporation process, making water harder to
during the drying process.
evaporate, it is important to have proper temperature controls
1.3 This practice can be used for compacted cylindrical and
in the chamber to ensure specimen remains at close to room
cubical bituminous laboratory and field specimens
temperature. Automatic controls within the unit allow the
1.4 This practice can also be used for drying other construc-
specimen to remain at close to room temperature by periodi-
tion materials such as concrete, soils, aggregates and loose
callyallowingaflowofwarmairtoenterthevacuumchamber.
asphalt mixtures. Use manufacturers recommendations for
Cycling between vacuum and airflow conditions allows the
drying other construction materials.
specimen to dry in a short period of time. Completely saturated
1.5 The values stated in SI units are to be regarded as the
specimens with over 30 g of retained water can be dried in
standard.
about 30 minutes. For most field cores that are not completely
1.6 This standard does not purport to address all of the
saturated the drying time is generally less than 15 minutes.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
NOTE 1—Cycle time (period) can depend on the material composition.
priate safety and health practices and determine the applica-
Each cycle involves an alternating period of 30 to 180 seconds of vacuum
operation and 30 to 120 seconds of air flow.
bility of regulatory requirements prior to use.
3.3 This method can be used for 100 mm diameter, 150 mm
2. Referenced Documents
diameter cylindrical, and cubical compacted bituminous speci-
2.1 ASTM Standards:
mens.
D5361 Practice for Sampling Compacted Bituminous Mix-
3.4 This method can also be used for drying loose asphalt
tures for Laboratory Testing
mixtures, aggregate samples and other solid specimens. Follow
manufacturers recommended procedures for drying specimens
3. Significance and Use
other than compacted bituminous specimens.
3.1 Specimen dry weight is a critical measure in determi-
3.5 This method can be used to determine moisture content
nation of accurate density and many other tests in the construc-
and amount of water loss during drying by weighing the
tion and raw materials industries. Drying specimens at room
sample before and after the drying operations.
temperature is required for some tests and provides an advan-
tage for other tests to ensure the integrity and to preserve the 4. Apparatus
characteristics of specimens.
4.1 Absorptive cloth or paper towels, for drying water from
surface of the specimens.
4.2 Vacuum Chamber, with a pump capable of evacuating a
This practice is under the jurisdiction of ASTM Committee D04 on Road and
sealed and enclosed chamber to a pressure of 6 mm Hg, when
Paving Materials and is the direct responsibility of Subcommittee D04.21 on
at sea level. The chamber shall be large enough to accommo-
Specific Gravity and Density of Bituminous Mixtures.
date specimens of 150 mm width or diameter and 180 mm in
Current edition approved Feb. 15, 2006. Published February 2006. DOI:
10.1520/D7227-06.
height. The device shall have an automatic vacuum, airflow
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
and temperature control features to ensure proper drying of the
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
specimen at close to room temperatures.Automatic controls of
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. the unit shall be calibrated by the manufacturer prior to initial
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D7227–06
FIG. 1 Water Removal Plate and Sample Holder Installed in Sample Chamber
use. The device
...
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