ASTM D6926-20

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it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D6926 − 16 D6926 − 20
Standard Practice for
Preparation of Asphalt Mixture Specimens Using Marshall
Apparatus
This standard is issued under the fixed designation D6926; 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 practice covers preparation and compaction of 4 in. (101.6 mm) diameter by nominal 2.5 in. (63.5 mm) high cylindrical
asphalt paving mixture specimens. This practice is intended for use with laboratory and plant-produced asphalt mixtures with
aggregate up to 1 in. (25.4 mm) maximum size and for recompaction of asphalt paving mixture samples.
NOTE 1—Historically, 35, 50, and 75 blows per face has been practiced for this test.
NOTE 2—Manufacturers do not recommend applying an excessive number of blows per face of a sample. This practice has been known to cause fatigue
and damage to machine components.
1.2 There are three types of Marshall compaction apparatus in use. The following types of hammer arrangements are included
in this practice:
1.2.1 Manually held hammer handle (Type 1) is attached to a flat compaction foot through a spring-loaded swivel and is hand
operated (see 5.3.1) (original standard developed by the United States Army Corps of Engineers).
1.2.2 Hammer handle restrained laterally (fixed) but not vertically, vertically (Type 2), attached to a flat compaction foot through
a spring-loaded swivel and is either mechanically or hand operated. operated (see 5.3.2). There may or may not be a constant
surcharge on top of the hammer handle. Mechanical hammers (Type 2) are available that operate at (1)a nominal 55 blows per
minute or range of 55 (2) equal to or greater than 75 to 68 blows per minute.
1.2.3 Hammer handle restrained laterally (fixed) with or without constant surcharge on top of hammer, is attached to a slanted
compaction foot on a rotating mold base, base (Type 3), and is mechanically operated. operated (see 5.3.3). This method must be
used as a referee method.
1.3 Although the mass and height of mass drop for each apparatus are the same, density achieved in compacted specimens with
the same number of blows will be different. It is up to the owner or specifier to establish the specific required number of blows
to be used for compaction of the specimen in relation to the field.
1.4 Units—The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are
mathematical conversions to SI units that are provided for information only and are not considered standard.
1.5 The text of this standard references notes and footnotes which provide explanatory material. These notes and footnotes
(excluding those in tables and figures) shall not be considered as requirements of the standard.
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.
2. Referenced Documents
2.1 ASTM Standards:
D8 Terminology Relating to Materials for Roads and Pavements
D3666 Specification for Minimum Requirements for Agencies Testing and Inspecting Road and Paving Materials
D4402D4402/D4402M Test Method for Viscosity Determination of Asphalt at Elevated Temperatures Using a Rotational
Viscometer
This practice is under the jurisdiction of ASTM Committee D04 on Road and Paving Materials and is the direct responsibility of Subcommittee D04.20 on Mechanical
Tests of Asphalt Mixtures.
Current edition approved Dec. 15, 2016Jan. 1, 2020. Published January 2017January 2020. Originally approved in 2004. Last previous edition approved in 20102016 as
D6926 – 10.D6926 – 16. DOI: 10.1520/D6926-16.10.1520/D6926-20.
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.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6926 − 20
D6927 Test Method for Marshall Stability and Flow of Asphalt Mixtures
E1 Specification for ASTM Liquid-in-Glass Thermometers
E11 Specification for Woven Wire Test Sieve Cloth and Test Sieves
E77 Test Method for Inspection and Verification of Thermometers
E2251 Specification for Liquid-in-Glass ASTM Thermometers with Low-Hazard Precision Liquids
3. Terminology
3.1 Definitions:
3.1.1 For definitions of terms used in this practice, refer to Terminology D8.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 lab mix lab compacted (LMLC) asphalt mixture, n—asphalt mix samples that are prepared in the laboratory by weighing
and blending each constituent then compacting the blended mixture after two hours 2 h of curing at the compaction temperature
or curing time specified by the owner, using a laboratory compaction apparatus.
3.2.1.1 Discussion—
LMLC typically occurs during the asphalt mixture design phase.
3.2.1.1 Discussion—
LMLC typically occurs during the asphalt mixture design phase.
3.2.2 plant mix laboratory compacted (PMLC) asphalt misture, n—asphalt mix samples that are manufactured in a production
plant, sampled prior to compaction, then immediately compacted using a laboratory compaction apparatus.
3.2.2.1 Discussion—
PMLC specimens are often used for quality control testing. This designation is limited to specimens that have not been permitted
to cool substantially, but PMLC samples may be placed in a laboratory oven to equilibrate the mix to the compaction temperature
before molding.
3.2.2.1 Discussion—
PMLC specimens are often used for quality control testing. This designation is limited to specimens that have not been permitted
to cool substantially, but PMLC samples may be placed in a laboratory oven to equilibrate the mix to the compaction temperature
before molding.
3.2.3 reheated plant mix lab compacted (RPMLC) asphalt mixture, n—asphalt mix samples that are manufactured in a
production plant, sampled prior to compaction, allowed to cool to room temperature, then reheated in a laboratory oven and
compacted using a laboratory compaction apparatus.
3.2.3.1 Discussion—
RPMLCs are often used for quality acceptance and verification testing. The reheating is as brief as possible to obtain uniform
temperature while avoiding artificial aging of the specimens. Asphalt mix conditioning, reheat temperature, and reheat time should
be defined in the applicable specification.
3.2.3.1 Discussion—
RPMLCs are often used for quality acceptance and verification testing. The reheating is as brief as possible to obtain uniform
temperature while avoiding artificial aging of the specimens. Asphalt mix conditioning, reheat temperature, and reheat time should
be defined in the applicable specification.
4. Significance and Use
4.1 Compacted asphalt mixture specimens molded by this procedure are used for various physical tests such as stability, flow,
indirect tensile strength, fatigue, creep, and modulus. Density and void analysis are also conducted on specimens for mixture
design and evaluation of field compaction.
NOTE 3—Uncompacted mixtures are used for determination of theoretical maximum specific gravity.
NOTE 4—The quality of the results produced by this practice are dependent on the competence of the personnel performing the procedure and the
D6926 − 20
capability, calibration, and maintenance of the equipment used. Agencies that meet the criteria of Specification D3666 are generally considered capable
of competent and objective testing, sampling, inspection, etc. Users of this practice are cautioned that compliance with Specification D3666 alone does
not completely ensure reliable results. Reliable results depend on many factors; following the suggestions of Specification D3666 or some similar
acceptable guideline provides a means of evaluating and controlling some of those factors.
5. Apparatus
5.1 Specimen Mold Assembly—Mold cylinders, base plates, and extension collars shall conform to the details shown in Fig. 1
(Compaction Mold).
5.2 Specimen Extractor—The specimen extractor shall have a steel disk that will enter the mold without binding and not be less
than 3.95 in. (100.3 mm) in diameter and 0.5 in. (12.7 mm) thick. The steel disk is used for extracting compacted specimens from
molds with the use of the mold collar. Any suitable extraction device such as a hydraulic jack apparatus or a lever arm device may
be used, provided the specimens are not deformed during the extraction process.
5.3 Compaction Hammers:
5.3.1 Compaction Hammers with a Manually Held (Type 1) or Fixed (Type 2) Handle, Handle (Type 1), either mechanically or
hand operated as generally as shown in Figs. 2 and 3Fig. 2, shall have a flat, circular compaction foot with spring-loaded swivel
and a 10 6 0.02 lb (4.545 6 0.009 kg) 0.02-lb (4.536 6 0.009-kg) sliding mass with a free fall freefall of 18 6 0.06 in. (457.2
6 1.5 mm) (see Fig. 23 for hammer tolerances). A typical manual compaction hammer is shown in Fig. 2. A typical mechanical
hammer is showed in Fig. 3.
in. (mm)
A 4.100 to 4.150 (104.1 to 105.4)
A 4.100 to 4.150 (104.1 to 105.4)
B 4.295 to 4.339 (109.1 to 110.2)
C 4.490 to 4.560 (114.0 to 115.8)
D 4.211 to 4.320 (107.0 to 109.7)
E 3.990 to 4.005 (101.3 to 101.7)
F 4.720 to 4.780 (119.9 to 121.4)
G 3.980 to 3.990 (101.1 to 101.3)
H 2.730 to 2.770 (69.3 to 70.4)
J 0.120 to 0.285 (3.0 to 7.2)
K 0.235 to 0.295 (6.0 to 7.5)
L 3.420 to 3.460 (86.9 to 87.9)
M 0.120 to 0.190 (3.0 to 4.8)
N 0.485 to 0.585 (12.3 to 14.9)
FIG. 1 Compaction Mold
D6926 − 20
in. (mm)
O – P Drop Distance 17.94 to 18.06 (455.7 to 458.7)
O–P Drop Distance 17.94 to 18.06 (455.7 to 458.7)
Q Guide Bushing . . . . . .
R Guide Rod Nominal Diameter 0.625 (15.9)
S Face Diameter Hardened Impact Resistant 3.860 to 3.960 (98.0 to 100.6)
T Foot Thickness 0.450 to 0.550 (11.4 to 14.0)
U Weight Face Diameter 1.960 to 2.040 (49.8 to 51.8)
X Spring . . . . . .
Z Finger Guard 2.95 to 4.50 (75.0 to 114.3)
lb. (kg)
lb (kg)
W Weight Mass 9.98 to 10.02 (4.527 to 4.545)
NOTE 1—Finger guard required only for Type 1 and Type 2 manual hand-operated compaction hammers. Hammers used in Type 2 mechanical and Type
3 rotating mechanical compaction hammers do not require a finger guard.
FIG. 23 Manual Compaction Hammer
NOTE 5—Manual Type 1 and Type 2 manual hand-operated compaction hammers should be equipped with a finger safety guard.
5.3.2 Compaction Hammers with a Fixed Handle (Type 2), either mechanically or hand operated as shown in Fig. 4(a) and Fig.
4(b), shall have a flat, circular compaction foot with spring-loaded swivel and a 10 6 0.02-lb (4.536 6 0.009-kg) sliding mass with
a freefall of 18 6 0.06 in. (457.2 6 1.5 mm) (see Fig. 3 for hammer tolerances).
D6926 − 20
FIG. 32 Typical Mechanical HammerManually Held Hammer (Type 1)
5.3.3 Mechanically Operated Compaction Hammers with a Fixed Hammer Handle, used with a constantly rotating base (Type
3) as shown in Fig. 5. There may or may not be a constant surcharge on top of handle, constantly rotating base, and mechanically
operated (Type 3), the handle. It shall have a slanted, circular tamping face and a 10 6 0.02 lb 0.02-lb (4.536 6 0.009 kg) 0.009-kg)
sliding weight with a free fall free-fall of 18 6 0.06 in. (457.2 6 1.5 mm). See Fig. 46 (Hammer Bevel Detail) for hammer and
tamping face bevel angle and tolerances, respectively. A rotating mechanism is incorporated in the base. The base rotation rate and
hammer blow rate shall be 18 to 30 rpm and 64 6 4 shall operate at a range of 55 to 68 blows per minute, respectively.
NOTE 6—Multiple hammer operation may affect the density of the samples.
5.4 Compaction Pedestal—The compaction pedestal shall consist of a 7.5 in. by 8.0 in. (191.0 mm by 203.2 mm) an 8.0 by
8.0-in. (203.2 by 203.2-mm) wooden post approximately 18 in. (457.2 mm) long, capped with a steel plate approximately 12 by
12 in. (304.8 by 304.8 mm) and 1 in. (25.4 mm) thick. The wooden post shall be oak, yellow pine, or other wood having an average
3 3
dry density of 42 to 48 lb ⁄ft (674.2 to 770.5 kg/m ). The wooden post shall be secured by bolts through four angleangled brackets
to a solid concrete slab. The steel cap shall be firmly fastened to the post. The pedestal assembly shall be installed so that the post
is plumb and the cap is level.
5.5 Specimen Mold Holder—With single-hammer compactors, the holder shall be mounted on the compaction pedestal so as to
center the compaction mold over the center of the post. The holders shall hold the compaction mold, collar, and base plate securely
in position during compaction of the specimen.
5.6 Ovens, Heating Pots, or Hot Plates—Circulating air ovens or thermostatically controlled heating pots and hot plates shall
be provided for heating aggregates, asphalt material, specimen molds, compaction hammers, and other equipment to within 5 °F
(3 °C) of the required mixing and compaction temperatures. Suitable shields, baffle plates, or sand baths shall be used on the
surfaces of the hot plates to minimize localized overhea
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