1、Designation: E 660 90 (Reapproved 2002)Standard Practice forAccelerated Polishing of Aggregates or Pavement SurfacesUsing a Small-Wheel, Circular Track Polishing Machine1This standard is issued under the fixed designation E 660; the number immediately following the designation indicates the year ofo
2、riginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.INTRODUCTIONThe Small-Wheel Circular Track Wear and Polishing Machine2i
3、s a device developed to rateaggregates and paving mixtures on their skid resistance after exposure to wearing and polishing. It isa small-diameter, circular track machine capable of accelerated wearing and polishing of pavementspecimens. Correlation and comparison can be accomplished through the use
4、 of control specimens thatare tested simultaneously with regular test specimens. Track capacity is twelve individual specimensper test run.The actual wearing and polishing for bituminous pavement specimens and exposed aggregatespecimens are provided by the action of four smooth pneumatic tires to el
5、iminate, as much as possible,the variables associated with tire tread pattern effects. The wheels are adjusted for camber and fortoe-out to provide scrubbing action for polishing without the aid of water or grinding compounds.To provide accelerated wear sufficient to remove the top textured layer fr
6、om portland-cement-concrete pavement specimens and to expose the coarse aggregate, as often encountered on wornpavements, that have been in use for substantial periods of time, the wear and polish procedure canbe modified by use of steel wheels having studs mounted in the periphery. The procedure fo
7、r concretespecimens consists of a period of operation with four smooth pneumatic tires to polish the as-builtsurface, followed by a period of accelerated wear using the steel wheels to expose the coarseaggregate, followed by a final polishing cycle using the four rubber tires again to polish the exp
8、osedaggregate.1. Scope1.1 This practice describes a laboratory procedure for esti-mating the extent to which aggregates or pavement surfaces arelikely to polish when subjected to traffic. Specimens to beevaluated for polishing resistance are placed in a circular trackand subjected to the wearing act
9、ion of four small-diameter,pneumatic tires without use of abrasive or water. Terminalpolish is achieved after approximately8hofexposure.2. Referenced Documents2.1 ASTM Standards:C 192 Practice for Making and Curing Concrete Test Speci-mens in the Laboratory3D 2240 Test Method for Rubber PropertyDuro
10、meterHardness4E 177 Practice for Use of the Terms Precision and Bias inASTM Test Methods5E 274 Test Method for Skid Resistance of Paved SurfacesUsing a Full-Scale Tire6E 303 Test Method for Measuring Surface Frictional Prop-erties Using the British Pendulum Tester6E 707 Test Method for Skid Resistan
11、ce of Paved SurfacesUsing the North Carolina State University Variable-SpeedFriction Tester63. Summary of Practice3.1 The circular track is fitted with twelve specimen holdersthat can be adapted to specimens of various shapes andthicknesses, but when mounted in the track, form a continuousplane runn
12、ing surface for the polishing wheels. A complete set1This practice is under the jurisdiction of ASTM Committee E17 on Vehicle-Pavement Systems and is the direct responsibility of Subcommittee E17.23 onSurface Characteristics Related to Tire-Pavement Slip Resistance.Current edition approved May 25, 1
13、990. Published July 1990. Originallypublished as E 66078. Last previous edition E 66083.2Mullen, W. G., Whitfield, J. K., Gibson, D., and Matlock, T. L., “Implemen-tation for Use of Variable Speed Friction Tester and Small Wheel Circular TrackWear and Polishing Machine,” Highway Research Program Pro
14、ject ERSD 110-76-2,Final Report; Available from National Technical Information Service, Springfield,VA 22161.3Annual Book of ASTM Standards, Vol 04.02.4Annual Book of ASTM Standards, Vol 09.01.5Annual Book of ASTM Standards, Vol 14.02.6Annual Book of ASTM Standards, Vol 04.03.1Copyright ASTM Interna
15、tional, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.of twelve specimens exposed to wear and polishing at the sametime is counted as a round of testing. Usually specimens aretested in sets of three per variable per round of test with threecontrol specimens of a
16、 standard surface included in each roundto allow comparison between rounds of testing. It is recom-mended that each variable be repeated in three separate rounds,making a minimum of nine specimens per variable to obtain anaverage polishing curve.3.2 To obtain a polishing curve, specimens are subject
17、ed topolishing action in the track until friction measurements showno substantial decrease in level with continued polishing effort.Measurements are recorded at the beginning of the test andperiodically throughout the test cycle to establish the shape ofthe polishing curve. Usually8hofexposure on th
18、e track at 30r/min or 7200 wheel passes per hour is sufficient to completethe polishing cycle for bituminous bound mixtures and exposedaggregate specimens. For portland-cement-concrete boundmixtures, it is recommended that a polish curve be obtained onthe original textured surface followed by remova
19、l of thesurface to expose the coarse aggregate using the steel-studdedabrading wheels. A polishing curve is then obtained for theexposed aggregate surface.3.3 Friction measurements can be obtained for bituminousplant mix type surfaces using the British Pendulum Tester inaccordance with Test Method E
20、 303. The British PendulumTester has been found to be ineffective in obtaining frictionmeasurements on highly textured surfaces such as bituminoussurface treatments and portland-cement-concrete surfaces.Therefore, it is recommended that the North Carolina StateUniversity Variable-Speed Friction Test
21、er2be used in accor-dance with Test Method E 707 as the friction measurementdevice on highly textured surfaces. With the Variable SpeedFriction Tester, speed gradients are obtainable in the laboratory.3.4 Interpretation of the laboratory polishing curves for fieldapplication is not included as part
22、of this practice.4. Significance and Use4.1 The use of laboratory obtained polishing curves andspeed gradients on proposed aggregate combinations andpavement mixtures are helpful tools in predicting the polishingcharacteristics of these surfaces if placed in field service.5. Apparatus5.1 Small-Wheel
23、 Circular Track2A power-driven deviceconsisting of four equally spaced wheels, independently sus-pended, on each of which may be mounted a smooth-treadpneumatic tire, operating over a circular track that holdsspecimens to be polished (Fig. 1).NOTE 1Construction plans are published in the reference c
24、ited infootnote 2.5.1.1 Rotating Wheel AssemblyFour individuallymounted wheel assemblies, free rolling, attached to the centralshaft. Tires are 11 3 6.00 3 5 nylon smooth no-pattern treadtires, 2-ply rating.7Each wheel may be individually adjustedfor distance from center shaft, plane of rotation (ca
25、mber), andtoe-in or toe-out. Tire pressure is maintained at 20 psi (138kPa) resulting in 13 psi (90 kPa) average contact pressureunder normal 72-lbf (320-N) wheel loading. Each wheelassembly has a horizontal fender onto which weights may befastened to increase the wheel loading. One pair of opposite
26、wheels is toed-out 2 while the other pair of wheels is toed in4 to produce an accelerated polishing action.5.1.2 Drive mechanism for the vertical central shaft is anelectric motor geared to rotate the shaft and wheel assembly at30 6 2 r/min or approximately 7200 wheel passes per hour.5.1.3 The circu
27、lar track is 36 in. (914 mm) in diameter to thecenter of the wheel travel path. There are spaces for individu-ally mounting twelve equally spaced specimen holders to makeup the track running surface. Specimen holders are clampedinto place to the supporting frame when testing is in progress.5.1.4 Spe
28、cimen holders or track segments are metal platessupported by three adjustable, lockable bolts for mounting andleveling each specimen before and during testing as necessary.5.1.4.1 Trapezoidal specimens sawed to size are mounted onthe bottom plate of the specimen holder. No top plate is used.7Availab
29、le from Goodyear Tire and Rubber Co., Akron, OH 44316.FIG. 1 NCSU Wear and Polishing MachineMark IIE 66025.1.4.2 Circular specimens or cores at least 6 in. (152 mm)in diameter are mounted on the bottom plate of the specimenholder, and a top plate with the appropriate diameter circularhole is used to
30、 complete the track running surface betweenadjacent circular specimens.5.1.4.3 Specimens are cemented to bottom plate using anepoxy glue or may be held in place by a clamping ring.NOTE 2Thermoplastic cements are unsatisfactory as they allow speci-mens to rotate or shift during the progress of the te
31、st.5.2 Electrical SystemThe electrical system consists ofthree circuits.5.2.1 The motor circuit is equipped with a slow-blow fuse toprotect the motor in case of overheating or machine lockup.5.2.2 The motor is controlled by a subtracting predeter-mined revolution counter.5.2.3 The safety guards are
32、interlocked so that the motorwill not operate unless guards are in operating position.5.3 Studded Steel Abrading WheelThe steel abradingwheel, fabricated from 12-in. (305-mm) diameter steel tubing,is mounted by inflating a pneumatic tire inside. Socket-headcap screws,14 20, used as studs, are arrang
33、ed in 60 rows andspaced 1.125 in. (28.6 mm) apart within rows with each screwoffset 0.375 in. (9.5 mm) from the one above. Two wheels arerecommended. Abrading wheels can only be used on trapezoi-dal specimens where no top specimen holder plate is required(Fig. 2).NOTE 3Construction plans are publish
34、ed in the reference cited infootnote 2.5.3.1 A fiber bristle brush is mounted behind one wheel tosweep the track surface when the abrading wheel is used (Fig.2).5.4 WeightsWeights of 50 lb (22.7 kg) may be added towheel assembly aprons when portland-cement concrete isbeing tested.5.5 Friction-Measur
35、ing DeviceAny friction-measuringdevice that will operate to within the center 3.5 by 5.06-in. (89by 129-mm) portion of a 6-in. (152-mm) diameter specimenwould be suitable provided the measurement can be taken inthe direction of traffic and the device can be taken into the fieldto be reasonably corre
36、lated with Test Method E 274 skid trailermeasurements.5.5.1 Friction measurements can be made on low macrotex-ture pavements or pavement samples using the British Pendu-lum Tester in Test Method E 303.5.5.2 Friction measurements can be made on any pavementsor pavement samples using the Variable Spee
37、d Friction Tester.2In addition, speed gradients may be obtained using this device.5.6 MoldsSpecimen molds may vary in size and shapedepending upon aggregate, mixture, or surface to be tested.5.6.1 Bituminous Laboratory SpecimenA 6-in. (152-mm)inside diameter mold is recommended for bituminous speci-
38、men compaction. The base should be detachable for specimenextraction. If static compaction in a compression machine isused, a 5.875-in. (149-mm) diameter compaction mold plungershould be provided.5.6.2 Concrete Laboratory SpecimensBecause of textur-ing, it is desirable to cast large concrete surface
39、s and to sawtrapezoidal specimens. A steel plate and angle iron mold 7.75by 28.0 by 2 in. (197 by 711 by 51 mm) deep will provide aslab from which three trapezoidal specimens can be sawed.5.6.3 Exposed Aggregate Laboratory SpecimensA 6-in.(152-mm) inside diameter mold approximately 1.8 in. (46 mm)in
40、 height is recommended for exposed aggregate specimenpreparation. The base should be detachable for specimenextraction.5.6.4 Cores and Thin SurfacingsThin or irregular backspecimens may be built up with plaster of paris to suitablemounting thicknesses of 1 to 2 in. (25 to 50 mm) using ringscut from
41、paper concrete cylinder molds.6. Materials6.1 Laboratory-Made Bituminous SpecimensIt is recom-mended that a standard laboratory aggregate for manufactureof control specimens be stocked in sufficient quantity forapproximately 1 year of operation, and that sufficient quantityFIG. 2 Studded Steel-Abrad
42、ing Wheels and Bristle Sweeping BrushE 6603shall be retained for recalibration of a new supply before theoriginal supply is exhausted.6.2 Laboratory-Made Portland Cement ConcreteSpecimensIt is recommended that standard laboratory coarseand fine aggregates for manufacture of control specimens bestock
43、ed in sufficient quantity for approximately 1 year ofoperation and that sufficient quantity shall be retained forrecalibration of a new supply before the original supply isexhausted.6.3 Laboratory-Made Exposed Aggregate SpecimensIt isrecommended that standard laboratory coarse aggregate for themanuf
44、acture of control specimens be stocked in sufficientquantity for approximately one year of operation and thatsufficient quantity shall be retained for recalibration of a newsupply before the original supply is exhausted.6.4 Specimen Mounting CementCommercially availableepoxy cement or a clamping rin
45、g shall be used for mountingspecimens.7. Sampling7.1 Not applicable, as sampling schemes may be varied tomeet the needs of the user.8. Test Specimens8.1 Bituminous Laboratory SpecimensUse a minimum ofthree individual specimens to evaluate each aggregate or eachpavement mixture design. Three rounds o
46、f three are recom-mended.8.1.1 Prepare bituminous specimens using the aggregategradation and asphalt cement content desired.8.1.1.1 Mix preheated aggregates and asphalt using a me-chanical laboratory mixer.8.1.1.2 Preheat the mold assembly (5.5.1) to mixing tem-perature and place a filter paper in t
47、he bottom of the mold.8.1.1.3 Distribute the mixture in the mold using a spatula,rodding around the mold sides and rodding and leveling thesurface. Place filter paper over the mixture.8.1.1.4 Place the compaction plunger in the mold andcompact the specimen in a compression machine to 3000 psi(20.68
48、MPa) holding the load for 2 min.NOTE 4At pressures in excess of 3000 psi (20.68 MPa) someaggregate particles may be crushed, resulting in possible bias of the testresults.8.1.1.5 Remove the plunger, cool the mold and specimen toroom temperature, and extract the specimen from the moldusing a hydrauli
49、c press.8.1.1.6 Mark the bottom surface as compacted as the testsurface, and store the specimen prior to use on a flat surface.8.1.2 Portland Cement Concrete Specimens:8.1.2.1 Mold portland cement concrete specimens in themolds described in 5.6.2 in accordance with Practice C 192,except that texture shall be imparted to the top surface usingthe desired texturing medium when the surface is sufficientlystiffened to retain the texture.8.1.2.2 Remove the molds and diamond-saw individualtrapezoidal specimens from the slab between 24 to 48 h aftermolding.8.1.2.3 Conti
