1、Designation: C779/C779M 05 (Reapproved 2010) C779/C779M 12Standard Test Method forAbrasion Resistance of Horizontal Concrete Surfaces1This standard is issued under the fixed designation C779/C779M; the number immediately following the designation indicates the yearof original adoption or, in the cas
2、e 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 Scope*1.1 This test method covers three procedures for determining the relative abrasion resis
3、tance of horizontal concrete surfaces.The procedures differ in the type and degree of abrasive force they impart, and are intended for use in determining variations insurface properties of concrete affected by mixture proportions, finishing, and surface treatment. They are not intended to providea q
4、uantitative measurement of the length of service that may be expected from a specific surface.1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. Within the text, theinch-pound units are shown in brackets. The values stated in each system may not b
5、e exact equivalents; therefore, each system shallbe used independently of each other.1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices an
6、d determine the applicability of regulatorylimitations prior to use. (WarningFresh hydraulic cementitious mixtures are caustic and may cause chemical burns to skin andtissue upon prolonged exposure.)2NOTE 1Other procedures are available for measuring the abrasion resistance of concrete surfaces in a
7、ddition to the three procedures contained in thistest method. Consideration should be given to Test Methods C944 and C418. The test method most closely representing service conditions should be used.2. Referenced Documents2.1 ASTM Standards:3C125 Terminology Relating to Concrete and Concrete Aggrega
8、tesC418 Test Method for Abrasion Resistance of Concrete by SandblastingC670 Practice for Preparing Precision and Bias Statements for Test Methods for Construction MaterialsC944 Test Method for Abrasion Resistance of Concrete or Mortar Surfaces by the Rotating-Cutter Method3. Terminology3.1 For defin
9、itions of terms used in this standard, refer to Terminology C125.4. Significance and Use4.1 The three test methods provide simulated abrasion conditions, which can be used to evaluate the effects on abrasionresistance of concrete, concrete materials, and curing or finishing procedures. They may also
10、 be used for quality acceptance ofproducts and surface exposed to wear. They are not intended to provide a quantitative measurement of length of service.4.2 The equipment used by each of these procedures is portable and thus suitable for either laboratory or field testing. The threeprocedures determ
11、ine the relative wear of concrete surfaces as follows:4.2.1 Procedure AThe revolving-disk machine operates by sliding and scuffing of steel disks in conjunction with abrasive grit.4.2.2 Procedure BThe dressing-wheel machine operates by impact and sliding friction of steel dressing wheels.4.2.3 Proce
12、dure CThe ball-bearing machine operates by high-contact stresses, impact, and sliding friction from steel balls.1 This test method is under the jurisdiction of ASTM Committee C09 on Concrete and Concrete Aggregatesand is the direct responsibility of Subcommittee C09.62 onAbrasion Testing.Current edi
13、tion approved Oct. 1, 2010Dec. 1, 2012. Published December 2010December 2012. Originally approved in 1974. Last previous edition approved in 20052010as C779 05.C779 05(2010). DOI: 10.1520/C0779_C0779M-05(2010).10.1520/C0779_C0779M-12.2 Section on Safety Precautions, Manual of Aggregate and Concrete
14、Testing,Annual Book of ASTM Standards, Vol. 04.02.3 For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This doc
15、ument is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as
16、 appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. Unite
17、d States1NOTE 2Diagrams of three machines meeting these specifications are shown in Fig. 1, Fig. 2, and Fig. 3.4PROCEDURE AREVOLVING DISKS5. Apparatus5.1 The function of the apparatus is dependent upon the abrasive action of the flat faces of three 60-mm (238-in.) diameter,cold-rolled steel revolvin
18、g disks, each attached to motor-driven vertical shafts which also revolve about a vertical axis. The insidediameter of the resulting circular and abraded track shall be approximately 150 mm (6 in.) and the outside diameter 275 mm (11in.). Crossed slots 90 to each other and cut 5 mm (316 in.) deep an
19、d 6 mm (14 in.) wide are located symmetrically in the abrasiveflat faces.5.2 The disks are free floating inasmuch as they are self-supporting and are driven transversely along a circular path at 12rev/min (12 rpm) while being individually turned on their own axis at 280 rev/min (280 rpm). Cups attac
20、hed at the top of the shaftof each disk shall be loaded with lead shot to produce a uniform total load of 22 N (5 lbf) on each abrading disk face.5.3 The abrasive grit shall consist of 250 No. 60 silicon carbide. This is fed from a storage cup mounted on the revolvingcircular plate through a 3-mm (1
21、8-in.) orifice passing through the plate. The flow of abrasive shall be controlled to a rate of 4 to6 g/min by an adjusting needle located in the orifice. The abrasive falls at the midwidth of the circular abraded track, and midwaybetween two of the disks.5.4 The micrometer bridge consists of a mach
22、ine-finished 25-mm (1-in.) rectangular steel bar of at least 300-mm (12-in.), clearspan supported by a tripod and drilled along its centerline with ten 3-mm (18-in.) diameter holes spaced 6-mm (14 in.) on center.The measuring instrument is a depth micrometre with a needle having an effective depth r
23、ange of 25 to 50 mm (1 to 2 in.) andgraduated to an accuracy of at least 0.025 mm (0.001 in.).4 The sole source of supply of these machines known to the committee at this time is White Machine Co., 9591 York Alpha Dr., North Royalton, OH 44133; SpiritFabricating, Ltd., 9260 Valley View Rd., Macedoni
24、a, OH 44056. If you are aware of alternative suppliers, please provide this information to ASTM International Headquarters.Your comments will receive careful consideration at a meeting of the responsible technical committee,1 which you may attend.FIG. 1 Revolving Disks Abrasion Test MachineC779/C779
25、M 1226. Test Specimen6.1 For laboratory test purposes, the machine is designed to accommodate approximately 300 by 300-mm (12 by 12-in.) testspecimens. The apparatus is equipped with an adjusting handle linked by a sprocket and chain-drive assembly to the four 25-mmFIG. 2 Dressing Wheel Abrasion Tes
26、t MachineFIG. 3 Ball Bearing Abrasion Test MachineC779/C779M 123(1-in.) diameter posts which support the entire rotating abrasion element. This feature permits the abrasion of test panels up toapproximately 100-mm (4-in.) in thickness. A zero adjustment in the height of the abrasion assembly also pe
27、rmits the use of theapparatus as a portable device for measuring the abrasion resistance on the surfaces in place as well as on test specimens.7. Procedure7.1 Prior to the test period, precondition the sample to remove curing compound and surface irregularities by running theabrasion machine for 5 m
28、in, after which the initial measurements shall be taken. Obtain initial measurements to an accuracy ofat least 0.025 mm (0.001 in.) of the test area by taking two series of 20 measurements each. Place the micrometer bridge so thatthe line of the second series of readings bisects at right angles to t
29、he first series of measurements. In making measurementssubsequent to the abrasion period, take care that the micrometer bridge is placed in precisely the same position in which thereference measurements were obtained. To ensure this, outline the ends of the positioned micrometer bridge on the surfac
30、e priorto making the initial measurements.7.2 A test period of 30 min generally produces significant wear on most concrete surfaces, but it is recommended to extend thetest period to 60 min, if information on the longtime abrasion resistance is desired.7.3 In using the device as a portable apparatus
31、, take care in the selection of the areas to be tested. Although the base of theapparatus is equipped with rubber pads, not only to prevent the apparatus from creeping during the abrasion operation but also tominimize the effect of slight variations in the level of the test areas. Select test areas
32、with a minimum of variation in level so asto eliminate the creeping effect.7.4 Take measurements of depth wear with a micrometer bridge as described in 4.45.4 to an accuracy of at least 0.025 mm(0.001 in.). Prior to each set of measurements, clean the specimen surface carefully by removing loose par
33、ticles.7.5 Make three tests on surfaces representative of the concrete to be evaluated. When wear of the disks reduces the depth ofthe slots to less than 1.5 mm (116 in.), they shall be replaced. New disk faces shall be subjected to a break-in period of at least15 min.8. Interpretation of Results8.1
34、 The comparison of measurements of average depth of wear of representative surfaces at 30 and 60-min exposure to abrasionwill indicate the relative abrasion resistance of these surfaces.9. Report9.1 Report the depth of wear of each surface tested as well as the average obtained on replicate surfaces
35、.9.2 Record mixture proportions (including cement content and water-cement ratio), specific gravities, grading of fine and coarseaggregates, Los Angeles abrasion test results, type and amount of material added to freshly placed concrete surface, type and extentof troweling, curing details, and age o
36、f concrete when tested.PROCEDURE BDRESSING WHEELS10. Apparatus10.1 The function of the apparatus is dependent upon the abrasive action of three sets of steel dressing wheels riding in a circularpath over a horizontal concrete surface. The dressing wheels in each of the three sets of wheels turn free
37、ly on a horizontal axleat the bottom of a free-floating, weighted, vertical steel shaft.10.2 Each of the three sets of seven dressing wheels are spaced so that each set cuts approximately a 40-mm (112-in.) wide path.The machine produces a circular abrasion path of about 140-mm (512-in.) inside diame
38、ter and 220-mm (812-in.) outside diameter.10.3 The apparatus shall consist of a motor-driven spider arrangement turning at 56 rev/min (56 rpm). The motor shall bemounted on a horizontal plate supported by four screw jacks allowing the motor to be raised and lowered. The spider shall be hungfrom the
39、vertical motor shaft. The three vertical shafts shall be mounted in the spider arrangement so that they rotate with the spiderand are free to move up and down in independent thrust-bearing sockets.10.4 The three shafts shall be fitted with a yoke inside, upon which a series of seven dressing wheels
40、are placed on a horizontalaxle. The mass of each complete dressing wheel assembly as it bears on the concrete surface shall be 7.5 kg (16.5 lb).10.5 The dressing wheels shall have an outside diameter of 60 mm (238 in.) and a thickness of 3 mm (18 in.) and shall beprovided with 18 flattened points, e
41、ach having dimensions of 3.0 by 2.0-mm (0.125 by 0.075 in.). The dressing wheels shall beassembled on the shaft alternated with steel washers. The total width of seven dressing wheels and eight washers shall beapproximately 40 mm (112 in.). The dressing wheels must be loose enough to turn freely and
42、 independently.10.6 The measuring instrument shall be a dial micrometer, reading to an accuracy of at least 0.025 mm (0.001 in.) with a rangeof at least 10 mm (0.4 in.). The contact end of the micrometer spindle shall have a spherical surface of 9.5-mm (38-in.) diameter.A jig located on the undersid
43、e of the spider holds the micrometre magnetically in the approximate center of the path of the dressingwheels.C779/C779M 12411. Test Specimen11.1 Place a sample approximately 300 by 300 by 100-mm (12 by 12 by 4-in.) thick into the machine and lock it in place withvises provided. Do not remove the sa
44、mple until the test is completed. Test three identical samples.12. Procedure12.1 Position the abrasion apparatus over surface to be tested. Rubber pads on the bottom of machine will hold the machinein place. Turn the screw crank until the full weight of each dressing-wheel shaft is resting on the co
45、ncrete surface. Lower the spideras far as possible without exerting any pressure from the spider itself onto these three shafts. Allow a spacing of 15 mm (0.5 in.)for vertical travel of the dressing wheels. Lock the screw crank to prevent any change in vertical movement of the spider duringtesting.1
46、2.2 Take an initial measurement to the nearest 0.025 mm (0.001 in.) on the test area with the dial micrometer in place whilerevolving the spider two revolutions by hand. Record this initial reading as a reference reading and then remove the micrometer.Start the machine and let it run for 30 min, bru
47、sh off the loose material, insert the dial micrometer, and record the average readingagain. If the readings are not reasonably uniform, record several readings taken around the circumference of the abraded surfacefrom which the average reading may be computed. The difference between the reference re
48、ading and the 30-min reading isindicative of the depth of wear.12.3 Make three tests on surfaces representative of the concrete to be evaluated. After every third test, install new dressingwheels.12.4 A test period of 30 min generally produces significant wear on most concrete surfaces, but it is re
49、commended to extendthe period to 60 min, if simulation of more severe abrasion is desired. Take depth-of-wear readings at 15-min intervals to thenearest 0.025 mm (0.001 in.) to obtain a time versus wear curve.13. Interpretation of Results13.1 The comparison of measurements of average depth of wear of representative surfaces at 30 and 60-min exposure toabrasion will indicate the relative abrasion resistance of these surfaces.13.2 A comparison of curves will indicate whether the resistance to abrasion is primarily at the surface or at a greater depth
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