ASTM D6111-24

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Designation: D6111 − 19a D6111 − 24
Standard Test Method for
Bulk Density And Specific Gravity of Plastic Lumber and
Shapes by Displacement
This standard is issued under the fixed designation D6111; 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*
1.1 This test method covers the determination of the bulk density and specific gravity of plastic lumber and shapes in their “as
manufactured” form. As such, this is a test method for evaluating the properties of plastic lumber or shapes as a product and not
a material property test method.
1.2 This test method is suitable for determining the bulk specific gravity or bulk density by immersion of the entire item or a
representative cross section in water. This test method involves the weighing of a one piece specimen in water, using a sinker with
plastics that are lighter than water. This test method is suitable for products that are wet by, but otherwise not affected by water
for the duration of the test.
NOTE 1—This test method was developed for application to plastic lumber materials, but it is generic enough that it would be equally applicable to other
plastic composite materials, including wood-plastic composite materials.
1.3 Plastic lumber and plastic shapes are currently made predominately from recycled plastics. However, this test method would
also be applicable to similar manufactured plastic products made from virgin resins where the product is non-homogeneous in the
cross-section.
1.4 The values stated in SI units are to be regarded as standard.
1.5 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, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
NOTE 2—There is no known ISO equivalent to this test method.
1.6 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
This test method is under the jurisdiction of ASTM Committee D20 on Plastics and is the direct responsibility of Subcommittee D20.20 on Plastic Lumber (Section
D20.20.01).
Current edition approved Aug. 1, 2019Feb. 1, 2024. Published August 2019February 2024. Originally approved in 1997. Last previous edition approved in 2019 as
D6111 - 19.D6111 – 19a. DOI: 10.1520/D6111-19A.10.1520/D6111-24.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6111 − 24
2. Referenced Documents
2.1 ASTM Standards:
D618 Practice for Conditioning Plastics for Testing
D883 Terminology Relating to Plastics
D1622/D1622M Test Method for Apparent Density of Rigid Cellular Plastics
D1898 Practice for Sampling of Plastics (Withdrawn 1998)
D5033 Guide for Development of ASTM Standards Relating to Recycling and Use of Recycled Plastics (Withdrawn 2007)
D6108 Test Method for Compressive Properties of Plastic Lumber and Shapes
E1 Specification for ASTM Liquid-in-Glass Thermometers
E12 Terminology Relating to Density and Specific Gravity of Solids, Liquids, and Gases (Withdrawn 1996)
E456 Terminology Relating to Quality and Statistics
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
E2935 Practice for Evaluating Equivalence of Two Testing Processes
3. Terminology
3.1 Definitions of Terms:
3.1.1 Definitions of terms applying to this test method appear in Terminology D883 and Guide D5033. For terms relating to
precision and bias and associated issues, the terms used in this test method are in accordance with the definitions in Terminology
E456.
3.1.2 density, bulk—the weight per unit volume of a material including voids inherent in material as tested. (Terminology D883)
3.1.3 plastic lumber, n—a manufactured product made primarily from plastic materials (filled or unfilled), typically used as a
building material for purposes similar to those of traditional lumber, which is usually rectangular in cross-section. (Terminology
D883)
3.1.3.1 Discussion—
Plastic lumber is typically supplied in sizes similar to those of traditional lumber board, timber and dimension lumber; however
the tolerances for plastic lumber and for traditional lumber are not necessarily the same. (Terminology D883)
3.1.4 resin, n—a solid or pseudosolid organic material often of high molecular weight, which exhibits a tendency to flow when
subjected to stress, usually has a softening or melting range, and usually fractures conchoidally. (Terminology D883)
3.1.4.1 Discussion—In a broad sense, the term is used to designate any polymer that is a basic material for plastics.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 plastic shape, n—a manufactured product made primarily from plastic materials (filled or unfilled), which is not necessarily
rectangular in cross section.
3.2.2 specific gravity, bulk (of solids)—the ratio of the weight in air of a unit volume of a permeable material (including both
permeable and impermeable voids normal to the material) at a stated temperature to the weight in air of equal density of an equal
volume of gas-free distilled water at a stated temperature.
3.2.2.1 Discussion—The accuracy of bulk density determinations is so low that corrections for air buoyancy and variations in
the value for the acceleration of gravity are not warranted. Hence, this definition is based on weights in air and not on mass. This
definition and discussion are based on the concepts in Terminology E12.
4. Summary of Test Method
4.1 Determine the weight of a specimen of the plastic lumber or shape in air. The specimen is then immersed in water, its weight
upon immersion is determined, and its bulk specific gravity calculated.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
The last approved version of this historical standard is referenced on www.astm.org.
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5. Significance and Use
5.1 The specific gravity or density of a solid is a property that can be measured conveniently to follow physical changes in a
sample, to indicate degree of uniformity among different sampling units or specimens, or to indicate the average density of a large
item.
5.2 It is possible that variations in density of a particular plastic lumber or shapes specimen will be due to changes in crystallinity,
loss of plasticizer/solvent content, differences in degree of foaming, or to other causes. It is possible that portions of a sample will
differ in density because of difference in crystallinity, thermal history, porosity, and composition (types or proportions of resin,
plasticizer, pigment, or filler).
NOTE 3—Reference is made to Test Method D1622/D1622M.
5.3 Density is useful for calculating strength to weight and cost to weight ratios.
5.4 If the cross-sectional area of the specimen is required for future testing on a particular sample, it is acceptable to determine
it from a specific gravity measurement, see Eq 4.
6. Apparatus
6.1 Balance—A balance large enough to accommodate the specimen conveniently, with a precision within 1.0 mg, accuracy within
0.05 % relative (that is 0.05 % of the weight of the specimen in air), and equipped with a means of support for the immersion cage.
6.1.1 Calibrate the balance at least annually in accordance with the manufacturer’s instructions for zero point, sensitivity, and
absolute accuracy.
6.2 Immersion Cage:
6.2.1 Wire—A corrosion-resistant wire for suspending the cage.
6.2.2 Cage—A device large enough to support the bottom of the specimen and when weighted will transfer the sinker force to the
specimen to keep it from floating. Refer to the sample immersion cage diagrammed in Fig. 1.
6.2.3 Sinker—A sinker for use with specimens of plastics that have specific gravities less than 1.000. The sinker shall: be
FIG. 1 Typical Configuration of Test Apparatus
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corrosion-resistant; have a specific gravity of not less than 7.0; have smooth surfaces and a regular shape; and be slightly heavier
than necessary to sink the specimen. It is important that the sinker be easily attached to the cage.
6.3 Immersion Vessel—A beaker, bucket, or other wide-mouthed vessel for holding the water and immersed cage.
6.4 Thermometer—A thermometer having not fewer than four divisions per °C over a temperature range of not less than 5°C above
and below the standard temperature, and having an ice point for calibration.
NOTE 4—A thermometer short enough to be handled inside the balance case will be found convenient. ASTM Thermometer 23C (see Specification E1)
and Anschütz-type thermometers have been found satisfactory for this purpose. Alternative thermometers with equivalent or better accuracy, precision,
and properties while covering the temperature range of 6.4 are acceptable.
7. Materials
7.1 Water—The water shall be distilled, deionized, or demineralized.
8. Sampling
8.1 The sampling units used for the determination of specific gravity shall be representative of the quantity of product for which
the data are required, in accordance with Practice D1898.
8.2 Plastic lumber and shapes are typically foamed, layered or hollow, varying in material properties over the cross section. To
establish the overall specific gravity for a section, complete unmachined elements or representative cross sections of these elements
shall be used.
9. Test Specimens
9.1 Test specimens for determining the bulk specific gravity or bulk density of plastic lumber and shapes shall be cut from the
“as manufactured” profile. Plastic lumber is generall
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