1、Designation: D 7564/D 7564M 09Standard Practice forConstruction of Asphalt-Rubber Cape Seal1This standard is issued under the fixed designation D 7564/D 7564M; the number immediately following the designation indicates theyear of original adoption or, in the case of revision, the year of last revisi
2、on. A number in parentheses indicates the year of lastreapproval. A superscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers asphalt-rubber cape seal, which isdefined as the application of an asphalt-rubber seal coat placedonto an ex
3、isting pavement surface, followed by the applicationof a conventional Type II or III slurry seal.NOTE 1An asphalt-rubber seal coat is also known as a stressabsorbing membrane (SAM) which consists of an asphalt-rubber mem-brane seal followed by the application of precoated aggregate chips.1.2 An asph
4、alt-rubber cape seal is commonly used to extendthe service life of low to medium trafficked and moderatelydistressed asphalt-surfaced pavements. The existing pavementcondition can be used to determine the application rates for theasphalt-rubber binder and aggregate as well as the aggregategradation.
5、 Pavements in relatively poor condition will requirea coarser aggregate with a higher binder application rate.1.3 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. The values stated ineach system may not be exact equivalents; therefore, eachsystem sha
6、ll be used independently of the other. Combiningvalues from the two systems may result in non-conformancewith the standard.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro
7、-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C 29/C 29M Test Method for Bulk Density (“Unit Weight”)and Voids in AggregateC117 Test Method for Materials Finer than 75-m (No.200) Sieve in Mineral
8、 Aggregates by WashingC 127 Test Method for Density, Relative Density (SpecificGravity), and Absorption of Coarse AggregateC 128 Test Method for Density, Relative Density (SpecificGravity), and Absorption of Fine AggregateC 131 Test Method for Resistance to Degradation of Small-Size Coarse Aggregate
9、 by Abrasion and Impact in the LosAngeles MachineC 136 Test Method for Sieve Analysis of Fine and CoarseAggregatesD 946 Specification for Penetration-Graded Asphalt Ce-ment for Use in Pavement ConstructionD 1139 Specification for Aggregate for Single or MultipleBituminous Surface TreatmentsD 2196 Te
10、st Methods for Rheological Properties of Non-Newtonian Materials by Rotational (Brookfield type) Vis-cometerD 2419 Test Method for Sand Equivalent Value of Soils andFine AggregateD 3381 Specification for Viscosity-Graded Asphalt Cementfor Use in Pavement ConstructionD 3910 Practices for Design, Test
11、ing, and Construction ofSlurry SealD 4791 Test Method for Flat Particles, Elongated Particles,or Flat and Elongated Particles in Coarse AggregateD 5360 Practice for Design and Construction of BituminousSurface TreatmentsD 5821 Test Method for Determining the Percentage ofFractured Particles in Coars
12、e AggregateD6114 Specification for Asphalt-Rubber BinderD 6373 Specification for Performance Graded AsphaltBinderD 6433 Practice for Roads and Parking Lots PavementCondition Index Surveys3. Significance and Use3.1 The procedure described in this practice is used todesign and construct an asphalt-rub
13、ber cape seal that willprovide a wearing course when subjected to low to mediumtraffic volumes and where the pavement distress is due toblock-type cracking resulting from pavement aging or reflec-tive cracking only (not where there are clear indications offatigue cracking due to repeated heavy axle
14、loads).1This practice is under the jurisdiction of ASTM Committee D04 on Road andPaving Materials and is the direct responsibility of Subcommittee D04.24 onBituminous Surface Treatments.Current edition approved Aug. 1, 2009. Published September 2009.2For referenced ASTM standards, visit the ASTM web
15、site, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United Sta
16、tes.NOTE 2Block cracking is defined in Practice D 6433. See AppendixX1 for an example of block cracking due to aging.4. Materials4.1 Asphalt-Rubber Seal Coat (or Stress AbsorbingMembraneSAM):4.1.1 Asphalt CementThe asphalt cement for the asphalt-rubber seal coat should comply with the requirements o
17、fSpecifications D 946, D 3381,orD 6373. Asphalt cementgrade selection is based on considerations of local climatic andtraffic conditions. The asphalt-rubber supplier should performroutine Q/C laboratory testing to ensure compatibility of theselected asphalt cement with the requirements of Specificat
18、ionD6114.4.1.2 Asphalt-RubberThe asphalt-rubber binder consistsof an interacted blend of paving grade asphalt cement, groundrecycled tire rubber, and other additives as needed to conformto the requirements of Specification D6114.4.1.3 AggregateAggregate consists of crushed materialsconforming to the
19、 physical requirements of SpecificationD 1139 for degradation, soundness, and deleterious substancesand, if the 4.75 mm No. 4 materials exceed 2 % of the totalweight of aggregate, a minimum sand equivalent value of 50when tested in accordance with Test Method D 2419 isrequired. At least 90 percent b
20、y weight of the coarse aggregateshall consist of crushed particles with at least two fracturedfaces as determined by Test Method D 5821.4.1.4 Aggregate GradationAggregate size is often repre-sented by one of the following gradations and determined inaccordance with Test Methods C 136 and C117. Other
21、 similargradations may be used, as appropriate.Sieve Size Percent Passing Percent Passing19.5mm34 in. 100 10012.5mm12 in. 95100 951009.50 mm 38 in. 020 70854.75 mm No. 4 05 0152.36 mm No. 8 02 050.075 mm No. 200 01 01NOTE 3The two examples shown in the table above are representativeof typical gradat
22、ions from current state highway or transportation depart-ments or other user agencies and from industry specifications forasphalt-rubber seal coat. Either gradation may be used for pavements withblock cracking (see Appendix X1). The first (predominately 12.5 mm 12in.) gradation is recommended for pa
23、vements with a high degree of blockcracking. The second (predominately 9.5 mm 38 in.) gradation isrecommended for pavements with a lesser degree of block cracking (seePractice D 6433, Figure X1.7 through X1.9).4.1.5 Selection of Coarse AggregateCoarse aggregateshall have abrasion values of less than
24、 30 percent in accordancewith Test Method C 131. Crushed gravel (if used) must have atleast 90 percent particles with two faces and 95 percentparticles with one face resulting from crushing in accordancewith Test Method D 5821. The percentage of flat and elongatedparticles should not exceed 10 %, wi
25、th a ratio of 5:1 inmaximum to minimum dimension, respectively, in accordancewith Test Method D 4791.4.1.6 DesignUnless project documents indicate other-wise, the seal coat shall be designed in accordance withPractice D 5360 in general, modified for asphalt-rubber appli-cations as described in this
26、practice. The asphalt-rubber binderis spray-applied using an application rate specified in Section5.1.2, followed by the application of aggregate chips using anapplication rate specified in 5.3.4.NOTE 4For more detailed asphalt-rubber seal coat design guidelinessee the Caltrans Maintenance Technical
27、 Advisory Guideline (MTAG).3Also shown in Appendix X2 is a suggested FHWA asphalt-rubber surfacetreatment design procedure.4.2 Emulsified Asphalt Slurry SealThe design and con-struction of the slurry seal shall conform to Practice D 3910.5. Construction of Asphalt-Rubber Cape Seal5.1 Application of
28、Asphalt-Rubber Binder:5.1.1 The following construction recommendations are rep-resentative of the state-of-the-art practice and are not aspecification.5.1.2 It is recommended that the asphalt-rubber binder forthe asphalt rubber seal coat be applied at a rate of 2.03.0L/m20.500.75 gallons/yd2. For pa
29、vement classified in faircondition with a Pavement Condition Index (PCI) rating of 35to 55 in accordance with Practice D 6433, a lower applicationrate (generally with a finer aggregate gradation) is recom-mended and should generally range from 2.02.5L/m30.500.65 gallons/yd2. For pavement classified
30、in poorcondition with a PCI rating of 25 to 35 in accordance withPractice D 6433, a higher application rate (generally with acoarser aggregate gradation) is recommended, generally in therange of 2.53.0 L/m30.650.75 gallons/yd2.5.1.3 It is recommended that the Asphalt-rubber binder beplaced upon a cl
31、ean, dry pavement surface. The pavementsurface temperature is generally limited to a minimum of 13C55F and rising when the asphalt rubber binder is applied.The recommended minimum atmospheric temperature shouldbe 16C 60F and rising.NOTE 5Placement of asphalt-rubber binder below the minimumtemperatur
32、es may cool the material to such a degree that the aggregatemay not embed and stick. This may lead to the premature loss of aggregateand bleeding or flushing of the surface.5.1.4 Distributor bar height, distribution speed and shieldingmaterials can be utilized to reduce the effects of wind on thespr
33、ay distribution. Typically distributor bar height varies be-tween 200 and 350 mm 814 in.NOTE 6When high gusting winds or dusty conditions (or both)prevent or adversely affect binder or aggregate spreading applicationoperations, the work should be suspended and rescheduled.5.1.5 All necessary equipme
34、nt should be in position andready to commence placement operations before starting thework.5.1.6 The asphalt rubber binder is applied to the pavementsurface after mixing and reacting, consistent with the require-ments of Specification D6114. The binder should be applied ata material temperature not
35、less than 195C 385F or morethan 215C 415F.5.1.7 Following the asphalt-rubber binder application, thebinder should be promptly covered with the pre-coated aggre-gate.3Caltrans, Maintenance Technical Advisory Guide (MTAG), State of CaliforniaDepartment of Transportation, Office of Pavement Preservatio
36、n, Division ofMaintenance, Sacramento, California, October, 2003.D 7564/D 7564M 092NOTE 7Experience has shown that if more than 2 minutes elapsebefore the covering of the asphalt-rubber binder, the cover aggregate maynot properly embed into the binder. This could lead to premature ravelingor unsuita
37、ble bleeding or flushing (or both) of the pavement surface.Pre-coated aggregate as described in 5.3.1 is preferred in order to ensurea good bond to the asphalt-rubber binder and avoid aggregate chip loss.5.2 Workmanship, Finish and Appearance:5.2.1 When joining edges against areas with aggregate, th
38、ejoints should be swept clean of excess aggregate prior to theadjacent application of asphalt rubber binder. Transverse jointsof this type are constructed by placing roofing paper orequivalent across and over the end of the previous asphaltrubber seal coat application. Once spraying has progressedbe
39、yond the paper, it should be removed immediately.5.2.2 The longitudinal joint between adjacent applicationsof aggregate should coincide with the line between designatedtraffic lanes. Longitudinal joints are overlapped for completecoverage.NOTE 8Overlapping of longitudinal joints is recommended to en
40、surecomplete aggregate coverage. Lack of overlapping may result in exposedasphalt-rubber binder without aggregate, which may cause excessivetracking of the asphalt-rubber binder. Generally, overlapping is between100 mm and 200 mm 48 in.5.2.3 At longitudinal joints with aggregate, the edges shouldbe
41、broomed back and blended to minimize differences inelevation, in order to provide a uniform appearance consistentwith the adjacent sealed surface. Care should be taken tominimize ridges and depressions in order to enhance unifor-mity of appearance.5.2.4 The application of asphalt rubber binder to ar
42、eas notaccessible with the distributor bar on the distributor truck isgenerally accomplished by using pressurized hand wands or byother appropriate means.5.3 Spreading Pre-coated Aggregate:5.3.1 Following the application of the asphalt rubber binder,the pre-coated aggregate is placed over areas rece
43、iving asphaltrubber binder. The aggregate should be pre-coated using0.51.0 % asphalt cement by weight of aggregate, conformingto Specifications D 946, D 3381,orD 6373.5.3.2 Aggregate for the asphalt rubber seal coat should bepre-coated at the hot plant at a temperature between 135C and165C 275325F a
44、nd then applied at a temperature not lessthan 105C (225F) after applying the asphalt rubber binder.5.3.3 No vehicle, including construction equipment, shouldbe driven over the asphalt rubber binder prior to the applicationof the pre-coated aggregate.5.3.4 The precoated aggregate is generally applied
45、 at a rateof 10.516.0 kg/m22334 lbs/yd2 depending on the pave-ment condition. For pavement in fair condition with a PCIrating of 40 to 55 in accordance with Practice D 6433, the finer9.5 mm 38 in. aggregate gradation (or a similar gradation) isrecommended, with a spread rate of 10.513.5 kg/m22330lbs
46、/yd2. For pavement in poor condition with a PCI rating of25 to 40 in accordance with Practice D 6433, the coarser 12.5mm 12 in. aggregate gradation (or a similar gradation) isrecommended with an spread rate of 12.016.0 kg/m22734lbs/yd2.NOTE 9Although an asphalt-rubber cape seal has been used onpavem
47、ents in poor condition, the designer should consider many factorsbefore such a surface treatment is employed on such a pavement. Inparticular, the poor pavement condition should be related to pavementaging and weathering, not traffic loads and fatigue cracking. All underly-ing subgrade or base failu
48、res (or both) should be corrected and anydrainage problems should be rectified.5.3.5 The spread rate is generally limited to any valuewithin 610 percent of the selected application rate duringspreading to provide a uniform appearance.NOTE 10The term “uniform appearance” refers to a surface that isge
49、nerally free of gaps, ridges, depressions, or other irregularities causedby the application of the asphalt rubber seal coat.5.4 Finishing of the Asphalt-Rubber Seal Coat:5.4.1 The first pass of the rollers over the new asphalt rubberseal coat consists of a minimum of one complete coverage(covering the entire width of the seal, moving forward), usingthe necessary number of pneumatic tired rollers. Rollingshould be completed as soon as practical using three completepasses
