ASTM D7564/D7564M-16(2023)

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.
Designation: D7564/D7564M − 16 (Reapproved 2023)
Standard Practice for
Construction of Asphalt-Rubber Cape Seal
This standard is issued under the fixed designation D7564/D7564M; 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 2. Referenced Documents
1.1 This practice covers asphalt-rubber cape seal, which is 2.1 ASTM Standards:
defined as the application of an asphalt-rubber seal coat placed C29/C29M Test Method for Bulk Density (“Unit Weight”)
onto an existing pavement surface, followed by the application and Voids in Aggregate
of a conventional Type II or III slurry seal. C117 Test Method for Materials Finer than 75-μm (No. 200)
Sieve in Mineral Aggregates by Washing
NOTE 1—An asphalt-rubber seal coat is also known as a stress
C127 Test Method for Relative Density (Specific Gravity)
absorbing membrane (SAM), which consists of an asphalt-rubber mem-
and Absorption of Coarse Aggregate
brane seal followed by the application of pre-coated aggregate chips.
C128 Test Method for Relative Density (Specific Gravity)
1.2 An asphalt-rubber cape seal is commonly used to extend
and Absorption of Fine Aggregate
the service life of low to medium trafficked and moderately
C131/C131M Test Method for Resistance to Degradation of
distressed asphalt-surfaced pavements. The existing pavement
Small-Size Coarse Aggregate by Abrasion and Impact in
condition can be used to determine the application rates for the
the Los Angeles Machine
asphalt-rubber binder and aggregate as well as the aggregate
C136/C136M Test Method for Sieve Analysis of Fine and
gradation. Pavements in relatively poor condition will require
Coarse Aggregates
a coarser aggregate with a higher binder application rate.
D946/D946M Specification for Penetration-Graded Asphalt
1.3 The values stated in either SI units or inch-pound units
Binder for Use in Pavement Construction
are to be regarded separately as standard. The values stated in
D1139/D1139M Specification for Aggregate for Single or
each system may not be exact equivalents; therefore, each
Multiple Asphalt Surface Treatments
system shall be used independently of the other. Combining
D2196 Test Methods for Rheological Properties of Non-
values from the two systems may result in nonconformance
Newtonian Materials by Rotational Viscometer
with the standard.
D2419 Test Method for Sand Equivalent Value of Soils and
1.4 This standard does not purport to address all of the Fine Aggregate
safety concerns, if any, associated with its use. It is the
D3381/D3381M Specification for Viscosity-Graded Asphalt
responsibility of the user of this standard to establish appro- Binder for Use in Pavement Construction
priate safety, health, and environmental practices and deter-
D3910 Practices for Design, Testing, and Construction of
mine the applicability of regulatory limitations prior to use. Slurry Seal
1.5 This international standard was developed in accor-
D4791 Test Method for Flat Particles, Elongated Particles,
dance with internationally recognized principles on standard- or Flat and Elongated Particles in Coarse Aggregate
ization established in the Decision on Principles for the
D5360 Practice for Design and Construction of Bituminous
Development of International Standards, Guides and Recom- Surface Treatments
mendations issued by the World Trade Organization Technical
D5821 Test Method for Determining the Percentage of
Barriers to Trade (TBT) Committee. Fractured Particles in Coarse Aggregate
D6114/D6114M Specification for Asphalt-Rubber Binder
This practice is under the jurisdiction of ASTM Committee D04 on Road and
Paving Materials and is the direct responsibility of Subcommittee D04.24 on
Asphalt Surface Treatments. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Dec. 1, 2023. Published December 2023. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 2009. Last previous edition approved in 2016 as D7564/D7564M – 16. Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/D7564_D7564M-16R23. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7564/D7564M − 16 (2023)
D6373 Specification for Performance-Graded Asphalt 4.1.5 Selection of Coarse Aggregate—Coarse aggregate
Binder shall have abrasion values of less than 30 % in accordance with
D6433 Practice for Roads and Parking Lots Pavement Con- Test Method C131/C131M. Crushed gravel (if used) must have
dition Index Surveys at least 90 % particles with two faces and 95 % particles with
one face resulting from crushing in accordance with Test
3. Significance and Use Method D5821. The percentage of flat and elongated particles
should not exceed 10 %, with a ratio of 5:1 in maximum to
3.1 The procedure described in this practice is used to
minimum dimension, respectively, in accordance with Test
design and construct an asphalt-rubber cape seal that will
Method D4791.
provide a wearing course when subjected to low to medium
4.1.6 Design—Unless project documents indicate otherwise,
traffic volumes and where the pavement distress is due to
the seal coat shall be designed in accordance with Practice
block-type cracking resulting from pavement aging or reflec-
D5360 in general, modified for asphalt-rubber applications as
tive cracking only (not where there are clear indications of
described in this practice. The asphalt-rubber binder is spray-
fatigue cracking due to repeated heavy axle loads).
applied using an application rate specified in 5.1.2, followed by
NOTE 2—Block cracking is defined in Practice D6433. See Appendix
the application of aggregate chips using an application rate
X1 for an example of block cracking due to aging.
specified in 5.3.4.
NOTE 4—For more detailed asphalt-rubber seal coat design guidelines,
4. Materials
see the Caltrans Maintenance Technical Advisory Guideline (MTAG).
4.1 Asphalt-Rubber Seal Coat (or Stress Absorbing Also shown in Appendix X2 is a suggested FHWA asphalt-rubber surface
treatment design procedure.
Membrane—SAM):
4.1.1 Asphalt Cement—The asphalt cement for the asphalt-
4.2 Emulsified Asphalt Slurry Seal—The design and con-
rubber seal coat should comply with the requirements of struction of the slurry seal shall conform to Practice D3910.
Specification D946/D946M, D3381/D3381M, or D6373. As-
5. Construction of Asphalt-Rubber Cape Seal
phalt cement grade selection is based on considerations of local
climatic and traffic conditions. The asphalt-rubber supplier
5.1 Application of Asphalt-Rubber Binder:
should perform routine Q/C laboratory testing to ensure
5.1.1 The following construction recommendations are rep-
compatibility of the selected asphalt cement with the require-
resentative of the state-of-the-art practice and are not a
ments of Specification D6114/D6114M.
specification.
4.1.2 Asphalt-Rubber—The asphalt-rubber binder consists
5.1.2 It is recommended that the asphalt-rubber binder for
of an interacted blend of paving grade asphalt cement, ground
the asphalt-rubber seal coat be applied at a rate of 2.0 to
2 2
recycled tire rubber, and other additives as needed to conform
3.0 L ⁄m [0.50 to 0.75 gal/yd ]. For pavement classified in fair
to the requirements of Specification D6114/D6114M.
condition with a Pavement Condition Index (PCI) rating of 35
4.1.3 Aggregate—Aggregate consists of crushed materials
to 55 in accordance with Practice D6433, a lower application
conforming to the physical requirements of Specification
rate (generally with a finer aggregate gradation) is recom-
D1139/D1139M for degradation, soundness, and deleterious
mended and should generally range from 2.0 to 2.5 L/m [0.50
substances and, if the –4.75 mm (–No. 4) materials exceed 2 %
to 0.65 gal/yd ]. For pavement classified in poor condition with
of the total weight of aggregate, a minimum sand equivalent
a PCI rating of 25 to 35 in accordance with Practice D6433, a
value of 50 when tested in accordance with Test Method
higher application rate (generally with a coarser aggregate
D2419 is required. At least 90 % by weight of the coarse
gradation) is recommended, generally in the range of 2.5 to
3 2
aggregate shall consist of crushed particles with at least two
3.0 L ⁄m [0.65 to 0.75 gal/yd ].
fractured faces as determined by Test Method D5821.
5.1.3 It is recommended that the asphalt-rubber binder be
4.1.4 Aggregate Gradation—Aggregate size is often repre-
placed upon a clean, dry pavement surface. The pavement
sented by one of the following gradations and determined in
surface temperature is generally limited to a minimum of 13 °C
accordance with Test Methods C136/C136M and C117. Other
[55 °F] and rising when the asphalt-rubber binder is applied.
similar gradations may be used, as appropriate.
The recommended minimum atmospheric temperature should
be 16 °C [60 °F] and rising.
Sieve Size Percent Passing Percent Passing
19.5 mm [ ⁄4 in.] 100 100
1 NOTE 5—Placement of asphalt-rubber binder below the minimum
12.5 mm [ ⁄2 in.] 95–100 95–100
9.50 mm [ ⁄8 in.] 0–20 70–85 temperatures may cool the material to such a degree that the aggregate
4.75 mm (No. 4) 0–5 0–15 may not embed and stick. This may lead to the premature loss of aggregate
2.36 mm (No. 8) 0–2 0–5
and bleeding or flushing of the surface.
0.075 mm (No. 200) 0–1 0–1
5.1.4 Distributor bar height, distribution speed, and shield-
NOTE 3—The two examples shown in the table above are representative
ing materials can be utilized to reduce the effects of wind on
of typical gradations from current state highway or transportation depart-
the spray distribution. Typically, distributor bar height varies
ments or other user agencies and from industry specifications for
between 200 and 350 mm [8 to 14 in.].
asphalt-rubber seal coat. Either gradation may be used for pavements with
block cracking (see Appendix X1). The first (predominately 12.5 mm
[ ⁄2 in.]) gradation is recommended for pavements with a high degree of
3 3
block cracking. The second (predominately 9.5 mm [ ⁄8 in.]) gradation is
Caltrans Maintenance Technical Advisory Guide (MTAG), State of California
recommended for pavements with a lesser degree of block cracking (see Department of Transportation, Office of Pavement Preservation, Division of
Practice D6433, Figs. X1.7 through X1.9). Maintenance, Sacramento, CA, October 2003.
D7564/D7564M − 16 (2023)
NOTE 6—When high gusting winds or dusty conditions (or both)
5.3.3 No vehicle, including construction equipment, should
prevent or adversely affect binder or aggregate spreading application
be driven over the asphalt-rubber binder prior to the application
operations, the work should be suspended and rescheduled.
of the pre-coated aggregate.
5.1.5 All necessary equipment should be in position and
5.3.4 The pre-coated aggregate is generally applied at a rate
2 2
ready to commence placement operations before starting the
of 10.5 to 16.0 kg/m [23 to 34 lb/yd ] depending on the
work.
pavement condition. For pavement in fair condition with a PCI
5.1.6 The asphalt-rubber binder is applied to the pavement rating of 40 to 55 in accordance with Practice D6433, the finer
surface after mixing and reacting, consistent with the require-
9.5 mm [ ⁄8 in.] aggregate gradation (or a similar gradation) is
ments of Specification D6114/D6114M. The binder should be recommended, with a spread rate of 10.5 to 13.5 kg/m [23 to
applied at a material temperature not less than 195 °C [385 °F]
30 lb/yd ]. For pavement in poor condition with a PCI rating of
or more than 215 °C [415 °F].
25 to 40 in accordance with Practice D6433, the coarser
5.1.7 Following the asphalt-rubber binder application, the 12.5 mm [ ⁄2 in.] aggregate gradation (or a similar gradation) is
binder should be promptly covered with the pre-coated aggre- recommended with a spread rate of 12.0 to 16.0 kg/m [27 to
gate. 34 lb/yd ].
NOTE 9—Although an asphalt-rubber cape seal has been used on
NOTE 7—Experience has shown that if more than 2 min elapse before
pavements in poor condition, the designer should consider many factors
the covering of the asphalt-rubber binder, the cover aggregate may not
before such a surface treatment is employed on such a pavement. In
properly embed into the binder. This could lead to premature raveling or
particular, the poor pavement condition should be related to pavement
unsuitable bleeding or flushing (or both) of the pavement surface.
aging and weathering, not traffic loads and fatigue cracking. All underly-
Pre-coated aggregate as described in 5.3.1 is preferred in order to ensure
ing subgrade or base failures (or both) should be corrected and any
a good bond to the asphalt-rubber binder and avoid aggregate chip loss.
drainage problems should be rectified.
5.2 Workmanship, Finish, and Appearance:
5.3.5 The spread rate is generally limited to any value
5.2.1 When joining edges against areas with aggregate, the
within 610 % of the selected application rate during spreading
joints should be swept clean of excess aggregate prior to the
to provide a uniform appearance.
adjacent application of asphalt-rubber binder. Transverse joints
of this type are constructed by placing roofing paper or
NOTE 10—The term “uniform appearance” refers to a surface that is
generally free of gaps, ridges, depressions, or other irregularities caused
equivalent across and over the end of the previous asphalt-
by the application of the asphalt-rubber seal coat.
rubber seal coat application. Once spraying has progressed
beyond the paper, it should be removed immediately. 5.4 Finishing of the Asphalt-Rubber Seal Coat:
5.4.1 The first pass of the rollers over the new asphalt-
5.2.2 The longitudinal joint between adjacent applications
rubber seal coat consists of a minimum of one complete
of aggregate should coincide with the line between designated
coverage (covering the entire width of the seal, moving
traffic lanes. Longitudinal joints are overlapped for complete
forward) using the necessary number of pneumatic tired
coverage.
rollers. Rolling should be completed as soon as practical using
NOTE 8—Overlapping of longitudinal joints is recommended to ensure
three complete passes, which is defined as the first rolling pass
complete aggregate coverage. Lack of overlapping
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