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Designation: D2168 − 10

Standard Practices for

Calibration of Laboratory Mechanical-Rammer Soil
Compactors1
This standard is issued under the fixed designation D2168; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.

1. Scope* However, the use of balances or scales recording pounds of

1.1 These practices for the calibration of mechanical soil mass (lbm) or the recording of density in lbm/ft3 shall not be
compactors are for use in checking and adjusting mechanical regarded as a nonconformance with this standard.
devices used in laboratory compacting of soil and soil- 1.6 This standard does not purport to address all of the
aggregate in accordance with Test Methods D698, D1557, safety concerns, if any, associated with its use. It is the
Practice D6026, and other methods of a similar nature that responsibility of the user of this standard to establish appro-
might specify these practices. Calibration for use with one priate safety and health practices and determine the applica-
practice does not qualify the equipment for use with another bility of regulatory limitations prior to use.
practice.
1.2 The weight of the mechanical rammer is adjusted as 2. Referenced Documents
described in 5.4 and 6.5 in order to provide for the mechanical 2.1 ASTM Standards:2
compactor to produce the same result as the manual compactor. D653 Terminology Relating to Soil, Rock, and Contained
1.3 Two alternative procedures are provided as follows: Fluids
D698 Test Methods for Laboratory Compaction Character-
Section
Practice A Calibration based on the compaction of a 5
istics of Soil Using Standard Effort (12 400 ft-lbf/ft3 (600
selected soil sample kN-m/m3))
Practice B Calibration based on the deformation of a 6 D1557 Test Methods for Laboratory Compaction Character-
standard lead cylinder
istics of Soil Using Modified Effort (56,000 ft-lbf/ft3
1.4 If a mechanical compactor is calibrated in accordance (2,700 kN-m/m3))
with the requirements of either Practice A or Practice B, it is D2487 Practice for Classification of Soils for Engineering
not necessary for the mechanical compactor to meet the Purposes (Unified Soil Classification System)
requirements of the other practice. D3740 Practice for Minimum Requirements for Agencies
1.5 The values stated in inch-pound units are to be regarded Engaged in Testing and/or Inspection of Soil and Rock as
as the standard. The values given in parentheses are for Used in Engineering Design and Construction
information only. D6026 Practice for Using Significant Digits in Geotechnical
1.5.1 It is common practice in the engineering profession to Data
concurrently use pounds to represent both a unit of mass (lbm) E11 Specification for Woven Wire Test Sieve Cloth and Test
and a force (lbf). This implicitly combines two separate Sieves
systems of units; that is, the absolute system and the gravita- E145 Specification for Gravity-Convection and Forced-
tional system. It is scientifically undesirable to combine the use Ventilation Ovens
of two separate sets of inch-pound units within a single
standard. This standard has been written using the gravitational 3. Significance and Use
system of units when dealing with the inch-pound system. In 3.1 Mechanical compactors are commonly used to replace
this system, the pound (lbf) represents a unit of force (weight). the hand compactors required for Test Methods D698 and
D1557 in cases where it is necessary to increase production.
1
These practices are under the jurisdiction of ASTM Committee D18 on Soil and
Rock and are the direct responsibility of Subcommittee D18.03 on Texture,
2
Plasticity and Density Characteristics of Soils. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved July 1, 2010. Published August 2010. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
apprroved in 1990. Last previous edition approved in 2002 as D2168–02a. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/D2168-10. the ASTM website.

*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

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 D2168 − 10
3.2 The design of mechanical compactors is such that it is adjustment. Clean, adjust, and lubricate the compactors so as to
necessary to have a calibration process that goes beyond meet all requirements of the manufacturer, and the applicable
determining the mass and drop of the hammer. method under which they will be used and for which the
NOTE 1—The quality of the result produced by this standard is mechanical compactor is to be calibrated. Operate the compac-
dependent on the competence of the personnel performing it, and the tor for a minimum of 25 drops to cause friction in the parts to
suitability of the equipment and facilities used. Agencies that meet the
criteria in Practice D3740 are generally considered capable of competent
become constant, allowing the rammer to fall on soil or other
and objective testing/sampling/inspection/and the like. Users of this soft material.
standard are cautioned that compliance with Practice D3740 does not in
NOTE 3—In order to provide satisfactory results, mechanical compac-
itself assure reliable results. Reliable results depend on many factors;
tors must be in excellent working condition. Improper operation of the
Practice D3740 provides a means of evaluating some of those factors.
raising and release mechanisms can introduce serious errors.
4. Apparatus 5.2 Obtain approximately 50 lb (23 kg) of soil classified as
4.1 For Practice A, in addition to the apparatus requirements CL in accordance with Classification D2487. If excessive
specified in Test Methods D698 and D1557, the following is moisture is present, dry the soil until it becomes friable. Drying
required: may be in air or by use of a drying apparatus such that the
4.1.1 Drying Oven——Thermostatically controlled oven, temperature of the sample does not exceed 140°F (60°C). Pass
preferably of the forced-draft type, meeting the requirements the soil through a No. 4 (4.75-mm) sieve conforming to the
for Specification E145 and capable of maintaining a uniform requirements of Specification E11. Discard any material re-
temperature of 140 6 5°F (60 6 3°C) throughout the drying maining on the sieve, and thoroughly blend the material
chamber. passing the sieve until it is uniform. The material shall then be
prepared for compaction in accordance with either Methods
4.2 For Practice B, in addition to the apparatus requirements D698 or D1557 as appropriate for the mechanical compactor
specified in Test Methods D698 and D1557, the following are being calibrated.
required:
4.2.1 Lead Deformation Apparatus—A lead deformation NOTE 4—The amount of soil used will vary greatly depending on the
apparatus consisting of an anvil, guide collar, and striking pin, number of water content unit mass determinations required.
as shown in Fig. 1. 5.3 Using the soil prepared in accordance with 5.2, deter-
4.2.2 Micrometer—A one-inch (25-mm) outside micrometer mine optimum moisture and maximum dry unit weight by
or caliper reading to 0.001 in. (0.02 mm), for determining the Method A of either Test Methods D698 or D1557 or whichever
length of the lead cylinders. As an alternative, a one-inch method is appropriate for the mechanical compactor being
(25-mm) dial comparator reading to 0.001 in. (0.02 mm) may calibrated. Prepare one curve using the mechanical compactor
be used to determine either the length of the lead cylinder, or and another using the manual compactor. Record the values of
of the complete lead deformation apparatus assembly. To γmax, the maximum dry unit weight obtained with the manual
measure the complete assembly, a dial comparator with a compactor, and γ'max, the maximum dry unit weight obtained
minimum opening of 2 in. (50 mm) is required (see Fig. 2). with the mechanical compactor.
NOTE 2—The use of vernier calipers is not recommended since the 5.4 Determine W, the percentage difference of maximum
vernier calipers can produce erroneous readings if not zeroed correctly, or dry unit weight values for a single set of data (see Section 7).
if the vernier caliper is not of high quality. If the absolute value of W is equal to or less than 2.0, the
4.2.3 Guide Sleeve Pedestal—A guide sleeve pedestal for mechanical compactor is satisfactory for immediate use. If the
use with guide sleeves used to control the drop of the manual absolute value of W is greater than 2.0, then obtain two
rammers in Test Methods D698 and D1557 (see Fig. 3). additional sets of data. Use the same soil sample, prepared in
4.2.4 Test Cylinders—A supply of commercially pure lead accordance with 5.2, that was used previously. Determine W,
test cylinders having individual weights such that the lightest the average percentage difference of maximum dry unit mass
cylinder is within 0.06 g of the heaviest, each having a length values for three sets of data (see Section 7). If the absolute
of 0.675 6 0.005 in. (17.1 6 0.1 mm) and a diameter of 0.310 value of W is equal to or less than 2.0, the mechanical
6 0.002 in. (7.87 6 0.05 mm).3 A minimum of ten test compactor is satisfactory for immediate use. If the absolute
cylinders is required for the calibration of one mechanical value of¯ W̄ is greater than 2.0, then adjust the rammer mass of
compactor. However, depending on circumstances, as many as the mechanical compactor in accordance with 5.5. Then secure
100 test cylinders may be required. three new values of γ'max and compute a new value of W̄.
Repeat this procedure until the absolute value of W̄ is equal to
5. Procedure—Practice A or less than 2.0.
5.1 Evaluate the mechanical and manual compactors for 5.5 Make changes in the weight of the mechanical hammer
evidence of wear, malfunction, and need of servicing and with due consideration to good workmanship. Makeshift modi-
fications that could affect the operation of the mechanical
3
The sole source of supply of the lead test cylinders known to the committee at compactor are not permitted. The maximum permissible varia-
this time is Hornady Manufacturing Co., P.O. Box 1848, Grand Island, Nebr. 68801 tion in the weight of the mechanical hammer as the result of
in lots of 500. If you are aware of alternative suppliers, please provide this
calibration is as follows: The total mass added to the original
information to ASTM International Headquarters. Your comments will receive
careful consideration at a meeting of the responsible technical committee,1 which mass of the hammer as received from the manufacturer must
you may attend. not exceed ten percent of its original mass. If it is necessary to

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 D2168 − 10

in. mm
2.10 53.34
1 7⁄8 48
1 5⁄8 41
1 1⁄2 38
1.250 31.75
1.248 31.70
0.626 15.90
0.625 15.88
1 ⁄2 13
0.317 8.05
1 ⁄4 6.4
1 ⁄8 3.2
1⁄16 1.6
1⁄32 0.79
0.005 0.13
0.004 0.10
0.002 0.05
0.001 0.02

NOTE 1—Inside dimension of guide collar should slip easily over raised section of anvil without excessive free play. Anvil should slip easily inside
guide sleeve pedestal without excessive free play.
FIG. 1 Lead Deformation Apparatus

add more than ten percent, The mechanical compactor is to be NOTE 5—Graphical procedures are helpful in estimating the correct
rebuilt or repaired. If the calibration indicates that the mass of amount of mass to be added or subtracted.
the original rammer needs to be reduced to less than 5.5 lbf 5.6 If a larger change than that permitted in 5.5 is found to
(2.49 kg) or 10 lbf (4.54 kg) depending on the test method be necessary, then improper operation of the mechanical
rammer standard, carefully recheck all equipment and calibra- compactor is indicated. Evaluate and adjust the mechanical
tions and report the procedure. If removal of mass is still compactor in order to determine and eliminate the cause of the
indicated, the height-of-drop should be adjusted. malfunction and repeat the calibration procedure.

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 D2168 − 10
5.7 Do not use the mechanical compactor if the indicated
weight change still exceeds that permitted in 5.5.

6. Procedure—Practice B
6.1 Evaluate and adjust the mechanical and manual com-
pactors as described in 5.1 of Practice A.
6.2 Deformation by the Manual Compactor—Obtain the
deformation value for the manual compactor as follows:
6.2.1 Select a set of lead cylinders from the same lot or
shipment. Remove any burrs from the ends of the lead
cylinders using a fine grade of emery cloth.
NOTE 6—Deformation of the lead cylinders is affected by changes in
temperature. Take precautions to maintain the cylinders within 65°F
(62.7°C) during the calibration of the mechanical compactor and the
securing of the manual compactor values.
6.2.2 Obtain c1, the (initial) micrometer or dial comparator
reading before impact, following the procedures decribed in
6.2.5.
in. mm
6.2.3 Place the base plate of the compaction mold on a rigid
8 203 foundation. On the base plate, place the assembled lead
3 76
2 51 deformation apparatus with the lead cylinder (see Fig. 4) and
1 25 guide sleeve pedestal in place. Insert the guide sleeve of the
1⁄ 4 6.4
1⁄ 8 3.2
manual compactor into the recess in the guide sleeve pedestal.
0.001 0.02 Check that the distance from rammer release point to striking
pin contact meets the specified requirements. Apply one drop
FIG. 2 Dial Comparator of the manual rammer with the guide sleeve of the manual
compactor held vertically, so that the rammer does not strike
the guide sleeve pedestal.
6.2.4 Obtain c2, the micrometer or dial comparator reading
after impact, following the procedures described in 6.2.5. The
difference between dial readings c1 and c2 is equal to D, the
deformation value.
6.2.5 Obtain readings for c1 and c2 either by:
6.2.5.1 Direct measurement of the length of the lead
cylinder, using the outside micrometer caliper or an equivalent
dial comparator.
6.2.5.2 Obtaining a measurement of the assembled defor-
mation apparatus, secured by placing it in the dial comparator

in. mm
2.77 70.4
2.13 54.10
3⁄ 8 10
1⁄ 8 3.2
0.03 0.8
0.005 0.13

NOTE 1—This dimension must be equal to the height of the lead

deformation apparatus when assembled with the lead cylinder in place,
within a tolerance of 60.01 in. (60.25mm).
NOTE 2—Diameter A is such that guide sleeve of rammer fits easily into
recess without free play.
FIG. 3 Guide Sleeve Pedestal

FIG. 4 Lead Deformation Apparatus Assembly

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 D2168 − 10
so that the top center of the 1⁄4-in. (6.4-mm) steel ball of the where:
striking pin is directly under the tip of the dial stem. W = percentage difference of maximum unit weight
6.2.6 Repeat 6.2.2 – 6.2.5 using an unused lead cylinder for values for a single set of data,
each determination until five deformation values are obtained W̄ = average percentage difference of maximum unit
that do not vary more than 2.0 % from D̄, the average value; weight values for three sets of data,
that is, the absolute value of v1 must be less than 2.0 for the five γmax = maximum unit weight value obtained by the manual
values selected (see 7.2). The deformation value for the manual method,
method shall be taken as D̄. γ̄max = average of three maximum unit weight values
obtained by the manual method,
6.3 Deformation by the Mechanical Compactor—Obtain the γ'max = maximum unit weight value obtained by the me-
deformation value (change in height) of the lead cylinder by chanical method, and
the mechanical compactor as follows: γ̄'max = average of three maximum unit weight values
6.3.1 Select a set of at least five lead cylinders from the obtained by the mechanical method.
same lot or shipment. Remove any burrs from the ends of the 7.2 Calculate the percentage difference of average lead
lead cylinders using a fine grade emery cloth (see Note 6). deformation values as follows:
6.3.2 Place the assembled lead deformation apparatus on the D 5 c1 2 c2 (2)
base of the mechanical compactor at such location that the
striking pin will be centered on the face of the rammer at the D̄ 5 ( ~c 1 2 c 2 ! /N
moment of contact of the two.
D' 5 c' 1 2 c' 2
6.3.3 Obtain the average deformation value D̄' for the
mechanical compactor using the same procedure specified in
6.2, except do not use the guide sleeve pedestal. The mechani-
D̄' 5 ( ~ c' 1 2 c' 2 ! /N

cal compactor must operate in the normal manner so as to lift ν 1 5 @ ~ D 2 D̄ ! /D̄ # 3 100
the rammer from the striking pin contact elevation to the
specified release height. Raising and releasing the rammer ν' 1 5 @ ~ D'2D̄' ! /D̄' # 3 100
manually or by any procedure other than that of normal
automatic operation is prohibited. It may be beneficial to ν 2 5 @ ~ D̄ 2 D̄' ! /D̄ # 3 100
temporarily suspend operation of the automatic turntable
during the calibration procedure. where:
6.3.4 Repeat 6.3.2 and 6.3.3 on remaining lead cylinders in c1 = micrometer or dial comparator reading before
set. impact, manual rammer,
c2 = micrometer or dial comparator reading after
6.4 Calculate v2, the percentage difference of the average impact, manual rammer,
deformation value, using the mechanical rammer, from the c'1 = micrometer or dial comparator reading before
average deformation value, using the manual rammer (see 7.2). impact, mechanical rammer,
If v2 does not vary more than 62.0, then the mechanical c'2 = micrometer or dial comparator reading after
compactor is satisfactory for immediate use. impact, mechanical rammer,
D = deformation value for single lead cylinder,
6.5 If v2 exceeds6 2.0, repeat 6.3.2 and 6.3.3, securing two manual rammer,
additional values of v2. Average the absolute value of all three D' = deformation value for single lead cylinder, me-
values of v2. If this average is equal to or less than 2.0, the chanical rammer,
mechanical compactor is satisfactory for immediate use. If the D̄andD̄' = average deformation values for manual and me-
absolute mean value of v2 is greater than 2.0, then adjust the chanical rammers respectively, where v1 and v'1
rammer weight of the mechanical rammer in accordance with values do not exceed 62.0 %,
5.5 and obtain additional sets of mechanical compactor data ν1 = percentage variation from the mean of individual
until the mean value of v2 for three sets of data is equal to or deformation values obtained using the manual
less than 2.0. rammer,
ν'1 = percentage variation from the mean of individual
6.6 Follow the same procedure as described for Practice A deformation values obtained using the mechani-
in 5.5, 5.6, and 5.7. cal rammer,
ν2 = percentage difference of the average deformation
7. Calculations value using the mechanical rammer from the
average deformation value using the manual
7.1 Calculate the percentage difference of maximum unit
rammer, and
weight values as follows: N = number of tests.
W 5 @ ~ γ' max 2 γ max! /γ max# 3 100 (1)
8. Report
W̄ 5 @ ~ γ̄' max 2 γ̄ max! /γ̄ max# 3 100 8.1 The report shall include the following information:

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 D2168 − 10
8.1.1 Identification of laboratory compactor by make, 8.1.8 Calculations, and
model, and serial number, 8.1.9 Initial and adjusted weights of rammer.
8.1.2 ASTM designation of laboratory compaction proce-
dure for which the compactor was calibrated, 9. Precision and Bias
8.1.3 Date of calibration,
8.1.4 Practice used (A or B), 9.1 These practices describe calibration methods that do not
8.1.5 For Practice A only: classification of soil used by produce a test result; therefore, neither a precision or bias
Classification D2487, statement is applicable.
8.1.6 For Practice A only: experimental values of γmax and
γ'max, 10. Keywords
8.1.7 For Practice B only: experimental values of c1, c'1, c2, 10.1 laboratory compaction; mechanical rammer; moisture
and c '2, density

SUMMARY OF CHANGES

Committee D18 has identified the location of selected changes to these practices since the last issue,
D2168–02a, that may impact the use of these practices. (Approved July 1, 2010)

(1) Added Practice D6026 to Scope and Referenced Docu- (5) Revised 5.5. Deleted old Note 5 and renumbered subse-
ments. quent notes.
(2) Added new 1.5.1. (6) Added a statement regarding turntable in 6.3.3.
(3) Replaced “thoroughly inspect” and “carefully inspect” with (7) Changed the standard from “Test Methods” to “Practices”
“evaluate” throughout. throughout.
(4) Added tolerances to 4.2.2.

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