ASTM E3004-22

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Designation: E3004 − 20a E3004 − 22
Standard Specification for
Preparation and Verification of Clay Blocks Used in
Ballistic-Resistance Testing of Torso Body Armor
This standard is issued under the fixed designation E3004; 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.
INTRODUCTION
At the time when work on this specification was undertaken, different ballistic-resistant body armor
test protocols required different impactors for verification of the clay blocks placed behind the test
items, and the lack of detailed guidance about the clay blocks resulted in different practices for
preparation and verification. To improve laboratory-to-laboratory consistency, major stakeholders
sought to harmonize practices related to the preparation and verification of the clay blocks used for
testing of ballistic-resistant body armor.
1. Scope
1.1 The purpose of this specification is to provide standardized methods for preparation and verification of backing assemblies
used in ballistic-resistant torso body armor testing and to reduce variability within and between laboratories.
1.2 The backing assembly is a clay block that contains ROMA Plastilina No. 1® clay as the backing material. The clay serves
as a witness material and provides a measurable indication of test item performance.
1.3 This specification identifies two clay-verification impactors that may be used: (1) cylindrical and (2) spherical. Purchasers and
other users will specify the clay-verification impactor to be used.
1.4 This specification is primarily directed toward test laboratories but may be applicable to body armor manufacturers,
researchers, and end users performing ballistic-resistance testing of body armor.
1.5 Units—The values stated in SI units are to be regarded as standard. The values given in parentheses are mathematical
conversions to non-SI units that are provided for information only.
1.6 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.
1.7 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 specification is under the jurisdiction of ASTM Committee E54 on Homeland Security Applications and is the direct responsibility of Subcommittee E54.04 on
Personal ProtectivePublic Safety Equipment (PPE).
Current edition approved July 1, 2020Oct. 1, 2022. Published July 2020October 2022. Originally approved in 2015. Last previous edition approved in 2020 as
E3004 – 20.E3004 – 20a. DOI: 10.1520/E3004-20A.10.1520/E3004-22.
U.S. Government standards require ROMA Plastilina No. 1®, from Sculpture House, Inc., as the backing material for ballistic-resistance testing.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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2. Referenced Documents
2.1 ASTM Standards:
E3005 Terminology for Body Armor
2.2 NIST Standard:
NIST Special Publication 330 The International System of Units (SI), 2008 Edition, Barry N. Taylor and Ambler Thompson,
Editors
3. Terminology
3.1 The terms and definitions of Terminology E3005 apply for the following terms: backing assembly, backing fixture, backing
material, bridge gauge, clay block, clay package, clay-verification impactor, depth gauge, striking device, and test item.
4. Significance and Use
4.1 U.S. Department of Defense and U.S. Department of Justice standards for assessing the performance of ballistic-resistant torso
body armor require the use of backing assemblies made with Roma Plastilina No. 1®. It can be demonstrated that the way the clay
block is handled prior to and during ballistic testing can have a significant influence on deformation of the clay when a test item
is struck by a projectile during testing.
4.2 At the time when work on this specification was undertaken, different ballistic-resistant body armor test protocols required
different impactors for verification of the clay blocks placed behind the test items, and the lack of detailed guidance about the clay
blocks resulted in different practices for preparation and verification. To improve laboratory-to-laboratory consistency, major
stakeholders sought to harmonize practices related to the preparation and verification of the clay blocks used for testing of
ballistic-resistant body armor.
5. Equipment
5.1 The equipment used for preparation and verification of clay blocks shall be as described below:
5.1.1 Backing Fixture—The backing fixture shall be a rigid, metal frame with a plywood bottom. The inside dimensions of the
metal frame shall be 610610 mm 6 2 mm (24.0(24.0 in. 6 0.08 in.) 0.08 in.) by 610610 mm 6 2 mm (24.0(24.0 in. 6 0.08 in.)
with a depth of 140 6 2 mm (5.5 6 0.08 in.). 140 mm 6 2 mm (5.5 in. 6 0.08 in.). The top and bottom edges of the metal frame
shall be planar. Plywood, of any grade, that is nominally “ ⁄4 in.” or “18 mm,” in.” or “18 mm,” shall be attached to the outside
of the metal frame to form the bottom of the fixture and shall be removable. See Fig. 1.
5.1.2 Backing Fixture Liner—A liner, such as 0.08 to 0.13 mm (3 to 5 mil) 0.08 mm to 0.13 mm (3 mil to 5 mil) polyethylene
sheeting, shall be inserted into the backing fixture to prevent the clay oils from coming into contact with the plywood. The liner
shall be placed against the plywood bottom of the backing fixture and shall not extend up the inside surfaces of the metal frame.
NOTE 1—The plywood bottom is shown larger than the metal frame for illustrative purposes only.
FIG. 1 Backing Fixture
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.
Available from National Institute of Standards and Technology (NIST), 100 Bureau Dr., Stop 1070, Gaithersburg, MD 20899-1070, http://www.nist.gov.
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NOTE 1—The backing fixture liner is intended to be a barrier between the clay and the plywood and may be sheeting, a coating (for example, spray, paint,
shellac), or any other barrier that prevents leaching of oil into the plywood.
5.1.3 Bridge Gauge—The bridge gauge shall be a rigid assembly that rests on two parallel strike face edges of the backing fixture
and supports a depth gauge that can slide back and forth on the assembly to measure depths across the surface of the backing
material. The depth gauge tip that touches the clay shall be hemispherical or spherical with a diameter of 6.35 6 0.0254 mm (0.25
6 0.001 in.) 6.35 mm 6 0.0254 mm (0.25 in. 6 0.001 in.) and attached to a cylindrical stem having a minimum length of 38.1
mm (1.5 in.) 38.1 mm (1.5 in.) and maximum diameter of 6.35 mm (0.25 in.) 6.35 mm (0.25 in.) such that only the tip touches the
deepest location of the indentation. The bridge gauge (independent of the backing fixture) shall have a resolution of 0.01 mm
0.01 mm or better with an accuracy of 60.1 mm or better.
5.1.4 Conditioning Chamber—The chamber shall be temperature controlled, be sufficiently large, and have continuous circulation
of air with the intention of uniformly heating all clay blocks in the chamber.
5.1.5 Cylindrical Clay-verification Impactor:
5.1.5.1 The impactor shall be a steel, constant diameter cylinder having a hemispherical end of diameter equal to the cylinder
diameter and a smooth transition from the hemispherical end to the cylinder body. A drawing specifying the dimensions of the
impactor is provided in Fig. 2.
5.1.5.2 The impactor mass shall be 1.01.0 kg 6 0.005 kg0.005 kg (2.20 lb (2.20 6 0.01 lb0.01 lb ).
m m
NOTE 2—To achieve the required mass, the length of the entire impactor will be approximately 90 mm (3.5 in.).
FIG. 2 Impactor
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FIG. 3 Template for Impact Locations
5.1.6 Spherical Clay-verification Impactor:
5.1.6.1 The impactor shall be a steel sphere having mass of 1043 6 5 g (2.29 6 0.01 lb) 1043 g 6 5 g (2.29 lb 6 0.01 lb) and
a diameter of 63.5 6 0.05 mm (2.5 6 0.001 in.).63.5 mm 6 0.05 mm (2.5 in. 6 0.001 in.).
5.1.7 Striking Device—The striking device shall be a metal, straight-edged blade capable of spanning two parallel strike face edges
of the backing fixture so that the backing fixture serves as the reference for the clay block surface. The striking device shall be
sufficiently rigid to facilitate creation of a flat clay surface that is even with the strike face edges of the backing fixture.
5.1.8 Template—A circular template shall be used to mark the impact locations on the surface of the clay. The template shall fit
within the internal backing fixture dimensions. The impact location centers on the template shown in Fig. 3 are spaced
approximately 50 mm (2 in.), 127 mm (5 in.), and 203 mm (8 in.) 50 mm (2 in.), 127 mm (5 in.), and 203 mm (8 in.) from the
center and approximately 120° apart.
5.1.8.1 The template shall be centered on the clay block, with the template’s outer perimeter extending to the inner edge of the
backing fixture frame.
5.1.8.2 The purpose of the template is to ensure that the three impact locations meet the drop spacing requirements below:
(1) Minimum of 76 mm (3.0 in.) from backing fixture edge to nearest indentation edge.
(2) Minimum of 152 mm (6.0 in.) between impactor indentation centers.
5.1.9 Test Setup for Cylindrical Clay-verification Impactor—The test setup for clay block verification using the cylindrical
clay-verification impactor shall consist of a guide tube through which the impactor is dropped (hemispherical end down) onto a
clay block that rests on a movable support. See Fig. 4 for an example test setup including guide tube dimensions and spacing
between the guide tube and the clay block surface.
5.1.9.1 Guide Tube—The guide tube length shall be such that the impactor is within the tube prior to release and entirely out of
the tube at impact with the clay block surface. The guide tube length shall be sufficient to minimize yaw of the impactor at the
clay surface. The guide tube inside diameter shall be sized to allow the impactor to drop freely and minimize yaw. The guide tube
shall be solidly mounted to a fixed surface.
NOTE 3—Holes or slots along the length of the guide tube may be useful to limit effects of air on the impactor as it drops through the tube.
5.1.9.2 Movable Support—The support upon which the clay block rests shall allow positioning of the clay block to set the impact
locations, keep the clay block level, keep the drop distance constant when the clay block is positioned for different impact
locations, and prevent the block from moving vertically due to the impact from the impactor.
A sphere, reference P/N 3606, supplied by Salem Specialty Ball Co., Inc., P.O. Box 145, West Simsbury, CT 06092, has been found to be satisfactory, although any steel
sphere meeting the requirements listed in this section is acceptable.
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FIG. 4 Example Test Setup
5.1.10 Test Setup for Spherical Clay-verification Impactor—The test setup for clay block verification using a spherical
clay-verification impactor shall consist of a mechanism to allow the sphere to drop freely from a height of 2.0 6 0.02 m (6.56 6
0.07 ft) 2.0 m 6 0.02 m (6.56 ft 6 0.07 ft) onto the clay block surface.
NOTE 4—Use of the spherical clay-verification impactor does not require velocity measurement.
5.1.11 Velocity Measurement Equipment—The velocity measurement equipment shall be capable of measuring velocities in at
least the range of interest with a resolution of 0.0050.005 m m/s ⁄s or better and an accuracy of 0.010.01 m m/s ⁄s or better. See
Appendix X1 for Velocity Measurement Guidance.
6. Procedures
6.1 Characterization of Clay Block Verification Test Setup when Using a Cylindrical Clay-verification Impactor:
6.1.1 Perform the following steps at installation of a new test setup (see 5.1.9) and periodically thereafter. These steps shall be
performed without the clay block or its movable support in the test setup.
6.1.1.1 Verify that the guide tube is straight, plumb, and rigid.
6.1.1.2 Verify that the guide tube is solidly mounted so that it remains in the verified position.
6.1.1.3 To verify the performance of the test setup, the velocity of the impactor at the clay surface is required to be between
6.156.15 m ⁄s to 6.276.27 m m/s. ⁄s. Perform an appropriate number of impactor drops through the guide tube to determine the drop
distance at which a velocity in this range is achieved at the expected point of impact. The drop distance shall be measured from
the impactor tip (rounded end) to the expected point of impact.
6.1.1.4 Record the drop distance. The drop distance shall be within 22 m 6 0.02 m.0.02 m.
NOTE 5—If the measured drop distance does not meet this requirement, the test setup should be adjusted until the measured velocity and drop distance
are within the required ranges.
6.1.2 The value of the measured drop distance shall be used during clay block verifications. The velocity is not required to be
measured during actual clay block verifications.
NOTE 6—Provision should be made to ensure that the impactor is dropped the determined drop distance each time, such as by the use of a hard stop at
the top of the guide tube.
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6.2 Clay Block Preparation Procedures:
6.2.1 New Clay Block Assembly:
6.2.1.1 Fill the backing fixture with clay following the steps below:
(1) Open each clay package, and soften the clay by heating it; working it with kneading, pounding, or tamping; or combinations
thereof.
(2) Press clay into the backing fixture, using a manual device (for example, mallet) or a machine (for example, hydraulic press
or powered hammering tool), one layer at a time starting in the corners. One layer of flattened clay should be added at a time, and
then pressed and blended into the previous layers to prevent voids.
(3) Continue layering, pressing, and blending of clay until the depth of the clay exceeds the strike face edges of the backing
fixture.
(4) Remove excess clay at the surface by drawing the striking device at least once across the full length of parallel edges of
the backing fixture.
NOTE 7—The striking device should be drawn across the same edges that the bridge gauge rests on during measuring and should be drawn in the same
direction every time.
NOTE 8—If the striking device is drawn more than once and in orthogonal directions, the resultant clay surface must be planar.
(5) Visually verify that the clay surface is flat and flush with the backing fixture strike face edges. If voids in the surface are
visible, fill those voids with additional clay, and repeat steps (4) and (5) until the surface of the clay is flat with no visible voids.
(6) Store the clay block indoors at room temperature or in the conditioning chamber.
6.2.2 Determination of Co
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