1、Designation: C 779/C 779M 05Standard Test Method forAbrasion Resistance of Horizontal Concrete Surfaces1This standard is issued under the fixed designation C 779/C 779M; the number immediately following the designation indicates the yearof original adoption or, in the case of revision, the year of l
2、ast revision. A number in parentheses indicates the year of last reapproval.A superscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers three procedures for determin-ing the relative abrasion resistance of horizontal concretesurfa
3、ces. The procedures differ in the type and degree ofabrasive force they impart, and are intended for use indetermining variations in surface properties of concrete af-fected by mixture proportions, finishing, and surface treatment.They are not intended to provide a quantitative measurement ofthe len
4、gth of service that may be expected from a specificsurface.1.2 The values stated in SI units or inch-pound units are tobe regarded separately as standard. Within the text, theinch-pound units are shown in brackets. The values stated ineach system are not exact equivalents; therefore, each systemshal
5、l be used independently of each other.1.3 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-priate safety and health practices and determine the applica-bility of regulatory li
6、mitations prior to use. (WarningFreshhydraulic cementitious mixtures are caustic and may causechemical burns to skin and tissue upon prolonged exposure.)2NOTE 1Other procedures are available for measuring the abrasionresistance of concrete surfaces in addition to the three procedurescontained in thi
7、s test method. Consideration should be given to TestMethods C 944 and C 418. The test method most closely representingservice conditions should be used.2. Referenced Documents2.1 ASTM Standards:3C 418 Test Method for Abrasion Resistance of Concrete bySandblastingC 670 Practice for Preparing Precisio
8、n and Bias Statementsfor Test Methods for Construction MaterialsC 944 Test Method for Abrasion Resistance of Concrete orMortar Surfaces by the Rotating-Cutter Method3. Significance and Use3.1 The three test methods provide simulated abrasionconditions, which can be used to evaluate the effects onabr
9、asion resistance of concrete, concrete materials, and curingor finishing procedures. They may also be used for qualityacceptance of products and surface exposed to wear. They arenot intended to provide a quantitative measurement of length ofservice.3.2 The equipment used by each of these procedures
10、isportable and thus suitable for either laboratory or field testing.The three procedures determine the relative wear of concretesurfaces as follows:3.2.1 Procedure AThe revolving-disk machine operatesby sliding and scuffing of steel disks in conjunction withabrasive grit.3.2.2 Procedure BThe dressin
11、g-wheel machine operatesby impact and sliding friction of steel dressing wheels.3.2.3 Procedure CThe ball-bearing machine operates byhigh-contact stresses, impact, and sliding friction from steelballs.NOTE 2Diagrams of three machines meeting these specifications areshown in Fig. 1, Fig. 2, and Fig.
12、3.4PROCEDURE AREVOLVING DISKS4. Apparatus4.1 The function of the apparatus is dependent upon theabrasive action of the flat faces of three 60-mm (238-in.)diameter, cold-rolled steel revolving disks, each attached tomotor-driven vertical shafts which also revolve about a verticalaxis. The inside diam
13、eter of the resulting circular and abradedtrack shall be approximately 150 mm (6 in.) and the outsidediameter 275 mm (11 in.). Crossed slots 90 to each other andcut5mm(316 in.) deep and 6 mm (14 in.) wide are locatedsymmetrically in the abrasive flat faces.1This test method is under the jurisdiction
14、 of ASTM Committee C09 onConcrete and Concrete Aggregates and is the direct responsibility of SubcommitteeC09.62 on Abrasion Testing of Concrete.Current edition approved Dec. 15, 2005. Published January 2006. Originallyapproved in 1974. Last previous edition approved in 2000 as C 779 00.2Section on
15、Safety Precautions, Manual of Aggregate and Concrete Testing,Annual Book of ASTM Standards, Vol. 04.02.3For 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
16、 Document Summary page onthe ASTM website.4The sole source of supply of these machines known to the committee at thistime is White Machine Co., 9591 YorkAlpha Dr., North Royalton, OH 44133; SpiritFabricating, Ltd., 9260 Valley View Rd., Macedonia, OH 44056. If you are awareof alternative suppliers,
17、please provide this information to ASTM InternationalHeadquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee,1which you may attend.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United Sta
18、tes.FIG. 1 Revolving Disks Abrasion Test MachineFIG. 2 Dressing Wheel Abrasion Test MachineC 779/C 779M 0524.2 The disks are free floating inasmuch as they are self-supporting and are driven transversely along a circular path at12 rev/min (12 rpm) while being individually turned on theirown axis at
19、280 rev/min (280 rpm). Cups attached at the top ofthe shaft of each disk shall be loaded with lead shot to producea uniform total load of 22 N (5 lbf) on each abrading disk face.4.3 The abrasive grit shall consist of 250 No. 60 siliconcarbide. This is fed from a storage cup mounted on therevolving c
20、ircular plate through a 3-mm (18-in.) orifice passingthrough the plate. The flow of abrasive shall be controlled to arate of 4 to 6 g/min by an adjusting needle located in theorifice. The abrasive falls at the midwidth of the circularabraded track, and midway between two of the disks.4.4 The microme
21、ter bridge consists of a machine-finished25-mm (1-in.) rectangular steel bar of at least 300-mm (12-in.),clear span supported by a tripod and drilled along its centerlinewith ten 3-mm (18-in.) diameter holes spaced 6-mm (14 in.) oncenter. The measuring instrument is a depth micrometre with aneedle h
22、aving an effective depth range of 25 to 50 mm (1 to 2in.) and graduated to an accuracy of at least 0.025 mm (0.001in.).5. Test Specimen5.1 For laboratory test purposes, the machine is designed toaccommodate approximately 300 by 300-mm (12 by 12-in.)test specimens. The apparatus is equipped with an a
23、djustinghandle linked by a sprocket and chain-drive assembly to thefour 25-mm (1-in.) diameter posts which support the entirerotating abrasion element. This feature permits the abrasion oftest panels up to approximately 100-mm (4-in.) in thickness. Azero adjustment in the height of the abrasion asse
24、mbly alsopermits the use of the apparatus as a portable device formeasuring the abrasion resistance on the surfaces in place aswell as on test specimens.6. Procedure6.1 Prior to the test period, precondition the sample toremove curing compound and surface irregularities by runningthe abrasion machin
25、e for 5 min, after which the initialmeasurements shall be taken. Obtain initial measurements toan accuracy of at least 0.025 mm (0.001 in.) of the test area bytaking two series of 20 measurements each. Place the microme-ter bridge so that the line of the second series of readingsbisects at right ang
26、les to the first series of measurements. Inmaking measurements subsequent to the abrasion period, takecare that the micrometer bridge is placed in precisely the sameposition in which the reference measurements were obtained.To ensure this, outline the ends of the positioned micrometerbridge on the s
27、urface prior to making the initial measurements.6.2 A test period of 30 min generally produces significantwear on most concrete surfaces, but it is recommended toextend the test period to 60 min, if information on the longtimeabrasion resistance is desired.6.3 In using the device as a portable appar
28、atus, take care inthe selection of the areas to be tested. Although the base of theapparatus is equipped with rubber pads, not only to prevent theapparatus from creeping during the abrasion operation but alsoto minimize the effect of slight variations in the level of the testareas. Select test areas
29、 with a minimum of variation in level soas to eliminate the creeping effect.6.4 Take measurements of depth wear with a micrometerbridge as described in 4.4 to an accuracy of at least 0.025 mm(0.001 in.). Prior to each set of measurements, clean thespecimen surface carefully by removing loose particl
30、es.FIG. 3 Ball Bearing Abrasion Test MachineC 779/C 779M 0536.5 Make three tests on surfaces representative of theconcrete to be evaluated. When wear of the disks reduces thedepth of the slots to less than 1.5 mm (116 in.), they shall bereplaced. New disk faces shall be subjected to a break-in perio
31、dof at least 15 min.7. Interpretation of Results7.1 The comparison of measurements of average depth ofwear of representative surfaces at 30 and 60-min exposure toabrasion will indicate the relative abrasion resistance of thesesurfaces.8. Report8.1 Report the depth of wear of each surface tested as w
32、ellas the average obtained on replicate surfaces.8.2 Record mixture proportions (including cement contentand water-cement ratio), specific gravities, grading of fine andcoarse aggregates, Los Angeles abrasion test results, type andamount of material added to freshly placed concrete surface,type and
33、extent of troweling, curing details, and age of concretewhen tested.PROCEDURE BDRESSING WHEELS9. Apparatus9.1 The function of the apparatus is dependent upon theabrasive action of three sets of steel dressing wheels riding ina circular path over a horizontal concrete surface. The dressingwheels in e
34、ach of the three sets of wheels turn freely on ahorizontal axle at the bottom of a free-floating, weighted,vertical steel shaft.9.2 Each of the three sets of seven dressing wheels arespaced so that each set cuts approximately a 40-mm (112-in.)wide path. The machine produces a circular abrasion path
35、ofabout 140-mm (512-in.) inside diameter and 220-mm (812-in.)outside diameter.9.3 The apparatus shall consist of a motor-driven spiderarrangement turning at 56 rev/min (56 rpm). The motor shall bemounted on a horizontal plate supported by four screw jacksallowing the motor to be raised and lowered.
36、The spider shallbe hung from the vertical motor shaft. The three vertical shaftsshall be mounted in the spider arrangement so that they rotatewith the spider and are free to move up and down inindependent thrust-bearing sockets.9.4 The three shafts shall be fitted with a yoke inside, uponwhich a ser
37、ies of seven dressing wheels are placed on ahorizontal axle. The mass of each complete dressing wheelassembly as it bears on the concrete surface shall be 7.5 kg(16.5 lb).9.5 The dressing wheels shall have an outside diameter of60 mm (238 in.) and a thickness of 3 mm (18 in.) and shall beprovided wi
38、th 18 flattened points, each having dimensions of3.0 by 2.0-mm (0.125 by 0.075 in.). The dressing wheels shallbe assembled on the shaft alternated with steel washers. Thetotal width of seven dressing wheels and eight washers shall beapproximately 40 mm (112 in.). The dressing wheels must beloose eno
39、ugh to turn freely and independently.9.6 The measuring instrument shall be a dial micrometer,reading to an accuracy of at least 0.025 mm (0.001 in.) with arange of at least 10 mm (0.4 in.). The contact end of themicrometer spindle shall have a spherical surface of 9.5-mm(38-in.) diameter. A jig loca
40、ted on the underside of the spiderholds the micrometre magnetically in the approximate center ofthe path of the dressing wheels.10. Test Specimen10.1 Place a sample approximately 300 by 300 by 100-mm(12 by 12 by 4-in.) thick into the machine and lock it in placewith vises provided. Do not remove the
41、 sample until the test iscompleted. Test three identical samples.11. Procedure11.1 Position the abrasion apparatus over surface to betested. Rubber pads on the bottom of machine will hold themachine in place. Turn the screw crank until the full weight ofeach dressing-wheel shaft is resting on the co
42、ncrete surface.Lower the spider as far as possible without exerting anypressure from the spider itself onto these three shafts. Allow aspacing of 15 mm (0.5 in.) for vertical travel of the dressingwheels. Lock the screw crank to prevent any change in verticalmovement of the spider during testing.11.
43、2 Take an initial measurement to the nearest 0.025 mm(0.001 in.) on the test area with the dial micrometer in placewhile revolving the spider two revolutions by hand. Recordthis initial reading as a reference reading and then remove themicrometer. Start the machine and let it run for 30 min, brushof
44、f the loose material, insert the dial micrometer, and record theaverage reading again. If the readings are not reasonablyuniform, record several readings taken around the circumfer-ence of the abraded surface from which the average readingmay be computed. The difference between the referencereading
45、and the 30-min reading is indicative of the depth ofwear.11.3 Make three tests on surfaces representative of theconcrete to be evaluated. After every third test, install newdressing wheels.11.4 A test period of 30 min generally produces significantwear on most concrete surfaces, but it is recommende
46、d toextend the period to 60 min, if simulation of more severeabrasion is desired. Take depth-of-wear readings at 15-minintervals to the nearest 0.025 mm (0.001 in.) to obtain a timeversus wear curve.12. Interpretation of Results12.1 The comparison of measurements of average depth ofwear of represent
47、ative surfaces at 30 and 60-min exposure toabrasion will indicate the relative abrasion resistance of thesesurfaces.12.2 A comparison of curves will indicate whether theresistance to abrasion is primarily at the surface or at a greaterdepth.13. Report13.1 Plot the time versus depth of wear of tests
48、performedfor 30 and 60-min durations on three representative surfacelocations or specimens and determine the average line.13.2 Record the mixture proportions including cement con-tent and water-cement ratio, specific gravities, grading of fineC 779/C 779M 054and coarse aggregates, Los Angeles abrasi
49、on test results, typeand amount of material added to freshly placed concretesurface, type and extent of troweling, curing details, and age ofconcrete when tested.PROCEDURE CBALL BEARINGS14. Apparatus14.1 The function of the apparatus is dependent upon theabrasive action of a rapidly rotating ball bearing under load ona wet concrete test surface. Water is used to flush out looseparticles from the test path, bringing the ball bearing in contactwith sand and stone particles still bonded to the concretesurface, thus providing impact as well as sliding fric
