1、Designation: D 6927 06Standard Test Method forMarshall Stability and Flow of Bituminous Mixtures1This standard is issued under the fixed designation D 6927; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision.
2、 A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers measurement of resistance toplastic flow of 102 mm (4 in.) cylindrical specimens ofbituminous paving mixtur
3、e loaded in a direction perpendicularto the cylindrical axis by means of the Marshall apparatus. Thistest method is for use with dense graded bituminous mixturesprepared with asphalt cement (modified and unmodified),cutback asphalt, tar, and tar-rubber with maximum size aggre-gate up to 25 mm (1 in.
4、) in size (passing 25 mm (1 in.) sieve).1.2 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of th
5、e user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C 670 Practice for Preparing Precision and Bias Statementsfor Test Methods for Construction MaterialsD 1188
6、 Test Method for Bulk Specific Gravity and Densityof Compacted Bituminous Mixtures Using CoatedSamplesD 2726 Test Method for Bulk Specific Gravity and Densityof Non-Absorptive Compacted Bituminous MixturesD 3549 Test Method for Thickness or Height of CompactedBituminous Paving Mixture SpecimensD 675
7、2 Test Method for Bulk Specific Gravity and Densityof Compacted Bituminous Mixtures Using AutomaticVacuum Sealing MethodD 6926 Practice for Preparation of Bituminous SpecimensUsing Marshall Apparatus3. Significance and Use3.1 Marshall stability and flow values along with density;air voids in the tot
8、al mix, voids in the mineral aggregate, orvoids filled with asphalt, or both, filled with asphalt are usedfor laboratory mix design and evaluation of bituminous mix-tures. In addition, Marshall stability and flow can be used tomonitor the plant process of producing bituminous mixture.Marshall stabil
9、ity and flow may also be used to relativelyevaluate different mixes and the effects of conditioning such aswith water.3.1.1 Marshall stability and flow are bituminous mixturecharacteristics determined from tests of compacted specimensof a specified geometry. The Marshall Test can be conductedwith tw
10、o different types of equipment: (1) Method Ausing aloading frame with a load ring and a dial gauge for deformationor flow meter (Traditional Method) or (2) Method Busing aload-deformation recorder in conjunction with a load cell andlinear variable differential transducer (LVDT) or other auto-matic r
11、ecording device (Automated Method).3.1.2 Typically, Marshall stability is the peak resistance loadobtained during a constant rate of deformation loading se-quence. However, depending on the composition and behaviorof the mixture, a less defined type of failure has been observed,as illustrated in Fig
12、. 1. As an alternative method, Marshallstability can also be defined as the load obtained, when the rateof loading increase begins to decrease, such that the curvestarts to become horizontal, as shown in the bottom graph ofFig. 1. The magnitude of Marshall Stability varies withaggregate type and gra
13、ding and bitumen type, grade andamount. Various agencies have criteria for Marshall stability.3.1.3 Marshall flow is a measure of deformation (elasticplus plastic) of the bituminous mix determined during thestability test. In both types of failure, the Marshall flow is thetotal sample deformation fr
14、om the point where the projectedtangent of the linear part of the curve intersects the x-axis(deformation) to the point where the curve starts to becomehorizontal. As shown in Fig. 1, this latter point usuallycorresponds to the peak stability; however, as an alternativewhen the failure condition is
15、not clearly defined, it can be1This test method is under the jurisdiction of ASTM Committee D04 on Roadand Paving Materials and is the direct responsibility of Subcommittee D04.20 onMechanical Tests of Bituminous Mixtures.Current edition approved July 1, 2006. Published November 2006. Originallyappr
16、oved in 2004. Last previous edition approved in 2005 as D 6927 05e1.2For referenced ASTM standards, visit the ASTM website, 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 w
17、ebsite.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.FIG. 1 Flow Determination for Two Types of Specimen FailureD6927062selected as the point on the curve which is six (0.01 in.) flowpoints (or 1.5 mm) to the right of the tangent l
18、ine. There is noideal value but there are acceptable limits. If flow at theselected optimum binder content is above the upper limit, themix is considered too plastic or unstable and if below the lowerlimit, it is considered too brittle.3.1.4 The Marshall stability and flow test results are appli-cab
19、le to dense-graded bituminous mixtures with maximum sizeaggregate up to 25 mm (1 in.) in size. For the purpose of mixdesign, Marshall stability and flow test results should consist ofthe average of a minimum of three specimens at each incre-ment of binder content where the binder content varies inon
20、e-half percent increments over a range of binder content. Thebinder content range is generally selected on the basis ofexperience and historical testing data of the component mate-rials, but may involve trial and error to include the desirablerange of mix properties. Dense-graded mixtures will gener
21、allyshow a peak in stability within the range of binder contentstested. Stability, flow, density, air voids, and voids filled withasphalt binder, may be plotted against binder content to allowselection of an optimum binder content for the mixture. Theabove test properties may also be weighted differ
22、ently to reflecta particular mix design philosophy. In addition, a mixturedesign may be required to meet minimum voids in the mineralaggregate based on nominal maximum aggregate size in themixture.3.1.5 Field laboratory Marshall stability and flow tests onspecimens made with plant-produced bituminou
23、s mix mayvary significantly from laboratory design values because ofdifferences in plant mixing versus laboratory mixing. Thisincludes mixing efficiency and aging.3.1.6 Significant differences in Marshall stability and flowfrom one set of tests to another or from an average value ofseveral sets of d
24、ata or specimens, prepared from plant-produced mix may indicate poor sampling, incorrect testingtechnique, change of grading, change of binder content, or amalfunction in the plant process. The source of the variationshould be resolved and the problem corrected.3.1.7 Specimens will most often be pre
25、pared using PracticeD 6926 but may be prepared using other types of compactionprocedures as long as specimens satisfy geometry require-ments. Other types of compaction may cause specimens tohave different stress strain characteristics than specimensprepared by Marshall impact compaction. Marshall st
26、abilityand flow may also be determined using field cores from in situpavement for information or evaluation. However, these resultsmay not compare with results from laboratory-prepared speci-mens and shall not be used for specification or acceptancepurposes. One source of error in testing field core
27、s arises whenthe side of the core is not smooth or perpendicular to the corefaces. Such conditions can create stress concentrations inloading and low Marshall stability.4. Apparatus4.1 Breaking HeadThe testing head (Fig. 2) shall consistof upper and lower cylindrical segments of cast gray or ductile
28、iron, cast steel, or annealed steel tubing. The lower segmentshall be mounted on a base having two perpendicular guiderods or posts (minimum 12.5 mm (12 in.) in diameter)extending upwards. Guide sleeves in the upper segment shalldirect the two segments together without appreciable bindingor loose mo
29、tion on the guide rods. A circular testing head withan inside bevel having dimensions other than specified in Fig.2 has been shown to give results different from the standardtesting head.4.2 Compression Loading MachineThe compressionloading machine (Fig. 3) may consist of a screw jack mountedin a te
30、sting frame and shall be designed to load at a uniformvertical movement of 50 6 5 mm/min. (2.00 6 0.15 in./min).The design in Fig. 3 shows power being supplied by an electricmotor. A mechanical or hydraulic compression testing machinemay also be used provided the rate of loading can bemaintained at
31、50 6 5 mm/min (2.00 6 0.15 in./min).4.3 Load Measuring DeviceAs a minimum, a calibratednominal 20 kN (5000 lb) ring dynamometer (Fig. 3) with a dialindicator to measure ring deflection for applied loads isrequired. The 20 kN (5000 lb) ring shall have a minimumsensitivity of 50 N (10 lb). The dial in
32、dicator should begraduated in increments of 0.0025 mm (0.0001 in.) or finer.The ring dynamometer should be attached to the testing frame(see ring holding bar, Fig. 3) and an adapter (see ringdynamometer adapter, Fig. 3) should be provided to transmitload to the breaking head. The ring dynamometer as
33、semblymay be replaced with a load cell connected to a load-deformation recorder or computer provided capacity and sen-sitivity meet above requirements.NOTE 1A higher capacity ring dynamometer may be required forhigh-stability mixes. These include mixes with harsh, crushed aggregateand dense gradatio
34、n, as well as mixes made with very stiff binders.4.4 FlowmeterThe Marshall flowmeter consists of a guidesleeve and a gage (Fig. 4). The activating pin of the gage shallslide inside the guide sleeve with minimal friction and theguide sleeve shall slide freely over the guide post (see Fig. 4)of the br
35、eaking head. These points of frictional resistance shallbe checked before tests. Graduations of the flowmeter gageshall be increments of 0.25 mm (0.01 in.) or finer. Instead of aflowmeter, other devices such as an indicator dial or linearvariable differential transducer (LVDT) connected to a load-de
36、formation recorder or computer may be used. These alternatedevices should be capable of indicating or displaying flow(deformation) to the required sensitivity. These devices must bedesigned to measure and record the same relative movementbetween the top of the guide post and the upper breaking head.
37、4.5 Water BathThe water bath shall be deep enough tomaintain the water level a minimum of 30 mm (1.25 in.) abovethe top of specimens. The bath shall be thermostaticallycontrolled so as to maintain the specified test temperature61C (2F) at any point in the tank. The tank shall have aperforated false
38、bottom or be equipped with a shelf forsupporting specimens 50 mm (2 in.) above the bottom of thebath and be equipped with a mechanical water circulator.4.6 OvenAn oven capable of maintaining the specifiedtest temperature 61C (2F).4.7 Air BathThe air bath for mixtures containing cutbackasphalt binder
39、 shall be thermostatically controlled and shallmaintain the air temperature at 25 6 1C (77 6 2F).D6927063mm in.A 101.5 to 101.7 3.995 to 4.005B 21.7 minimum 0.855 minimumC 76.2 minimum 3.0 minimumD 41.15 to 41.40 1.620 to 1.630E 18.92 to 19.18 0.745 to 0.755F 2.0 reference 0.08 referenceG 8.89 to 9.
40、09 0.350 to 0.358H 101.3 minimum 3.990 minimumJ Forces transmitted through one spherical and one flat surface.K Geometry of guide system must be appreciably free of both play and binding. One test for binding is to lift or lower head by a single guide bushing.FIG. 2 Testing Head DimensionsFIG. 3 Com
41、pression MachineD6927064FIG. 4 Example of Flowmeter (Used in Method A)FIG. 5 Example of Assembly Using Compression Machine with LVDT and Plotter (Typical of Method B)D69270654.8 ThermometersCalibrated thermometers for water andair baths shall cover the temperature range specified and bereadable to 0
42、.2C (0.4F).5. Procedure5.1 A minimum of three specimens of a given mixture shallbe tested. The specimens should have the same aggregate type,quality, and grading; the same mineral filler type and quantity;and the same binder source, grade and amount. In addition, thespecimens should have the same pr
43、eparation, that is, tempera-tures, cooling, and compaction.5.2 Specimens should be cooled to room temperature aftercompaction. During cooling they should be placed on asmooth, flat surface. Bulk specific gravity of each specimenshall be determined by Test Methods D 2726, D 1188,orD 6752. The bulk sp
44、ecific gravities of replicate specimens foreach binder content shall agree within 60.020 of the mean asnoted in Practice D 6926.5.2.1 Measure specimen thickness according to Test MethodD 3549.5.3 Specimens can be conditioned for testing as soon as theyreach ambient room temperature. Testing shall be
45、 completedwithin 24 h after compaction. Bring specimens prepared withasphalt cement, tar, or tar-rubber to the specified temperatureby immersion in the water bath 30 to 40 min, or placement inthe oven for 120 to 130 min. Maintain the bath or oventemperature at 60 6 1C (140 6 2F) for asphalt cement,
46、49 61C (120 6 2F) for tar-rubber specimens, and 38 6 1C (1006 2F) for tar specimens. Bring specimens prepared withcutback asphalt to temperature by placing them in the air bathfor 120 to 130 min. Maintain the air bath temperature at 25 61C (77 6 2F).NOTE 2Temperature variation will affect test resul
47、ts. A dummyspecimen with a thermocouple can be used to monitor temperature.5.3.1 Thoroughly clean the guide rods and inside surfaces ofthe test head segments prior to conducting the test. Lubricateguide rods so that the upper test head segment slides freelyover them. The testing head shall be at a t
48、emperature of 20 to40C (70 to 100F). If a water bath is used, wipe excess waterfrom the inside of the testing head segments.5.3.2 Remove a specimen from the water, oven, or airconditioning bath (in the case of a water bath remove excesswater with a towel) and place in the lower segment of thetesting
49、 head. Place the upper segment of the testing head on thespecimen, and place the complete assembly in position in theloading machine. If used, place the flowmeter in position overone of the guide rods and adjust the flowmeter to zero whileholding the sleeve firmly against the upper segment of thetesting head. Hold the flowmeter sleeve firmly against theupper segment of the testing head while the test load is beingapplied.5.4 The elapsed time from removal of the test specimensfrom the water bath to the final load determination shall notexceed 30 s. App
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