1、Designation: D4796 17Standard Test Method forBond Strength of Thermoplastic Pavement MarkingMaterials1This standard is issued under the fixed designation D4796; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revis
2、ion. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method provides an instrumental means for thedetermination of thermoplastic pavement marking materialbond strengths us
3、ing cement bricks and loading fixtures.1.2 The values stated in inch-pound units are to be regardedas standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.1.3 This standard does not purport to address
4、all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety, health and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.4 This international standard was developed
5、in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents
6、2.1 ASTM Standards:2C109/C109M Test Method for Compressive Strength ofHydraulic Cement Mortars (Using 2-in. or 50-mm CubeSpecimens)D16 Terminology for Paint, Related Coatings, Materials, andApplicationsD4541 Test Method for Pull-Off Strength of Coatings UsingPortable Adhesion TestersD5179 Test Metho
7、d for Measuring Adhesion of OrganicCoatings in the Laboratory by Direct Tensile MethodD7234 Test Method for Pull-Off Adhesion Strength of Coat-ings on Concrete Using Portable Pull-Off Adhesion Tes-tersD7307 Practice for Sampling of Thermoplastic Traffic Mark-ing MaterialsD7308 Practice for Sample Pr
8、eparation of ThermoplasticPavement Marking MaterialsE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. Terminology3.1 The terms and definitions in Terminology D16 apply tothis met
9、hod.3.2 Definitions of Terms Specific to This Standard:3.2.1 cement brick, na type of brick (a solid masonry unit,rectangular in shape) made from a mixture of cement and sand,molded under pressure and cured under steam at 200F (93C);used as backing brick and where there is no danger of attackfrom ac
10、id or alkaline conditions. These bricks are not colorizedand have a compressive strength of 3000 to 5000 psi.3.2.2 loading fixture, n(also referred to as dollies, studs, orjigs) metal fixture round and flat on one end for bonding to testsample and shaped on the other end for attaching to tensiletest
11、ing device. Measurements are listed in inches. (Fig. 1).3.2.3 thermoplastic, npavement marking (same as 3.2.4).3.2.4 thermoplastic pavement marking, na highly filled100 % total solids highway marking system that when heatedto a molten state can be extruded or sprayed onto a road surfaceand when cool
12、ed forms a solid durable delineator or roadmarking thermoplastic usually melted to 425F (218C).4. Summary of Test Method4.1 The thermoplastic specimen is prepared for this test byfirst melting a sample to its application temperature undercontinuous agitation. The specimen is then applied to thespeci
13、fied cement brick using a hot drawdown bar (Fig. 2),heated to 220 6 5F (104 6 2C), at 125 mils (3.175 mm)thickness. While the thermoplastic is still soft, three cuts aremade with a 1.6 in. (40.6 mm) diameter die (Fig. 4), heated to220 6 5F (104 6 2C), in order to separate the test area fromthe rest
14、of the drawdown. The die may be heated while1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings, Materials, and Applications and is the direct responsibility ofSubcommittee D01.44 on Traffic Coatings.Current edition approved July 1, 2017. Published August 2
15、017. Originallyapproved in 1988. Last previous edition approved in 2010 as D4796 10. DOI:10.1520/D4796-17.2For 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 standa
16、rds Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decis
17、ion on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1submerged in glycerin to prevent thermoplastic from stickingto the die. The test areas are allowed to cool slightly and then
18、three 1.6 in. (40.6 mm) diameter heated loading fixtures arelaid on the test areas. The samples are then allowed to cureovernight before determining the bond strength on a tensiletesting device.5. Significance and Use5.1 The function of this test method is to provide numericalinstrumental results in
19、dicating the cohesive and/or adhesivebond strength of thermoplastic pavement marking to a speci-fied cement brick substrate.5.2 The use of this test method allows the user and manu-facturer to control the quality of the product and makeinferences about the performance of the thermoplastic pave-ment
20、marking product. Results from these tests also provideinformation helpful in researching and developing thermoplas-tic pavement marking materials.5.3 The method has been revised to be more consistent tomethodology in otherASTM bond methods for coatings in TestMethods D4541, D5179, and D7234.5.4 Stri
21、ct adherence to the procedures outlined is necessaryfor precision of the test method. Under no conditions shouldthe bond strength be accepted unless there is conformance tothe method.6. Types of Separation in Bond Strength Tests6.1 Thermoplastic to Loading Fixture SeparationThistype of separation oc
22、curs when:(a) an insufficient coverage of the thermoplastic to thefixture at time of placement,(b) material or jig temperature is too low.These type of separations are acceptable when the the resultsexceed the specified bond strength.6.2 Thermoplastic to Thermoplastic SeparationThis typeof separatio
23、n is caused by internal cohesive failure of thethermoplastic. This separation is acceptable when it exceedsthe specified bond strength.6.3 Thermoplastic to Cement Brick SeparationThis typeof separation is caused by the failure of the bond between thethermoplastic specimen and the cement brick. This
24、separationis acceptable when it exceeds the specified bond strength.6.4 Cement Brick to Cement BrickThis type of separationis caused by the internal cohesive failure of the brick. This isdue, in most cases, to a bond between the thermoplastic andcement brick that exceeds the cohesive strength of the
25、 cementbrick. This separation is not acceptable when the bond strengthvalues are lower than specified.7. Apparatus7.1 Loading Fixture (three), 1.6 in. (40.6 mm) diameter 2 sqin. (50.8 sq mm) area on one end and post for attaching to thetensile testing device and load cell (Fig. 1).7.2 Cement Bricks,
26、 3.75 by 2.5 by 7.75 in. (9 by 5.5 by 19cm) in size with a compressive strength of 3000 to 5000 psi(210.9 to 351.5 kg/m2).NOTE 1Cement bricks can be obtained at a local block plant or BlockUSA. Home improvement paving bricks usually do not have enoughcohesive strength. Concrete bricks conforming to
27、Test Method C109/C109M have been used but proved more variable due to migration of athin veneer of cement to the top of the brick making determinationserratic. The cement bricks may be obtained from local block plants. Theterm cement brick is common for the industry and is used in this testmethod ex
28、tensively.7.3 Tensile Testing Equipment with a minimum capacity of200 6 2 lbs (910 6 1 kg) having a pull-rate capability of atleast 0.275 in./min (7 mm/min).NOTE 2The unit should be fitted with a steel frame to hold the cementbrick for testing (see Fig. 3).7.4 Drawdown Bar, 2 by 1 by 4 in. (5 by 2.5
29、 by 10 cm) insize capable of laying down a 125 mil or 0.125 in. (3.175 mm)molten thermoplastic film 2 in. (50.8 mm ) wide (Fig. 2).7.5 Hot Plate, capable of maintaining 220 6 5F (104 62C).7.6 Oven, capable of maintaining 425 6 5F (218 6 2C).7.7 Die Cutter, 1.6 in. (40.6 mm) diameter (Fig. 4).7.8 Met
30、al Frame for holding concrete brick (Fig. 3).8. Sampling8.1 Samples may be obtained by following Practice D7307.FIG. 1 Loading FixtureD4796 172FIG. 2 Drawdown Bar (in inches)FIG. 3 Brick HolderD4796 1739. Procedure9.1 After sampling a batch of road marking thermoplasticby Practice D7307, prepare a r
31、epresentative molten sample fortesting by following Practice D7308.NOTE 3Premelted block thermoplastic can be sampled simply bybreaking off the required test size and melting down in the sample manneras prescribed in Practice D7308.9.2 Heat the drawdown bar (see 7.4) to approximately250F (121C) in a
32、n oven or on a hotplate.9.3 Obtain a dry room temperature cement brick that hasbeen brushed or sanded/shot blasted on the side to be coatedwith thermoplastic. This should remove any loose texturedsurface material that may negatively affect the results.9.4 Preheat the 1.6 in. (40.6 mm) diameter die a
33、nd 3 loadingfixtures to approximately 250F (121C) in an oven or on ahotplate.9.5 When the thermoplastic specimen is melted to 425F(218C) using a 2 oz. (50 or 100 ml) ladle, or per manufacturerrecommendation under continuous agitation as required in 9.1,obtain a sample of molten material from the con
34、tainer.9.6 Remove the drawdown bar from the hot plate or ovenand immediately place it on the cement brick. Pour the moltenthermoplastic in front of the drawdown bar and make thedrawdown the full length of the brick with the melted thermo-plastic.9.7 Remove the 1.6 in. (40.6 mm) diameter die cutter f
35、romthe oven or hotplate where it has been maintained at approxi-mately 220 6 5F (104 6 2C).9.8 Cut out three test areas uniformly spaced along thedrawdown thermoplastic.9.9 Allow the test area to come to room temperature, thenplace a hot-loading fixture on one of the three test areasallowing the the
36、rmoplastic on the surface of the test area toslightly melt and form a tight adhesive bond between thethermoplastic sample and the surface of the loading fixture.This can be aided by applying a slight downward pressure andtwisting about14 turn on the loading fixture.9.10 Allow the test sample and loa
37、ding fixtures to come toroom temperature.9.11 Place the brick in the brick holder (Fig. 5) attached tothe bottom of the tensile testing equipment.9.12 Line up the sample to be tested with the universal jointfrom the load cell on the tensile testing equipment.9.13 Pin the universal joint and the meta
38、l jig together.Check that they are in line vertically as much as possible.9.14 Set the tensile testing device to zero, and pull theloading fixture metal jig at 0.25 in./min. (6.35 mm/min).9.15 From the chart recorder or the units display, determinethe amount of force in kilograms at which the thermo
39、plasticand/or brick fails, and record the results.9.16 Repeat steps 9.12 9.15 to obtain the results of theother two samples.9.17 Three tests are run on each brick. Separations involv-ing at least 90 % of the thermoplastic area to the cement brick,thermoplastic to thermoplastic and cement brick to ce
40、mentbrick are acceptable for reporting bond strengths. Notations ofthe type of break should be made for each result. If two of thethree tests fail to meet these requirements, testing should berepeated until at least two test results meeting these conditionshave been obtained.FIG. 4 Die CutterD4796 1
41、7410. Calculations10.1 Calculate the bond strength as follows:10.1.1 Determine the mean of the three readings obtained in9.15 if the conditions in 9.17 are met.10.1.2 Divide the mean reading obtained by test area. Theresult is the bond strength in pounds per square inch (kilogramsper square meter).1
42、0.1.3 Discard results which do not meet the requirementsof 9.17, and repeat testing until three results with an acceptablefailure mode are obtained.11. Report11.1 Report the following information:11.1.1 The type of separation, bond strength, the batchnumber, color and type of thermoplastic.11.1.2 Th
43、e determination of the area of separation is sub-jective. The area not involved in the separation is usuallyattached to the loading fixture or cement brick.12. Precision and Bias312.1 The precision of this test method is based on aninterlaboratory study of Test Method D4796 for Bond Strengthof Therm
44、oplastic Pavement Marking Materials, conducted in2010. A single laboratory, with three technicians, participatedin this study. Each of the technicians tested two differentmaterials a total of six times over a period of two days. Everytest result reported represents an individual determination.Except
45、 for the use of only a single laboratory, Practice E691was followed for the design and analysis of the data; the detailsare given in ASTM Research Report No. RR:D01-1155.12.1.1 Repeatability Limit (r)Two test results obtainedwithin one laboratory shall be judged not equivalent if theydiffer by more
46、than the “r” value for that material; “r”istheinterval representing the critical difference between two testresults for the same material, obtained by the same operatorusing the same equipment on the same day in the samelaboratory.12.1.1.1 Repeatability limits are listed in Table 1.12.1.2 Reproducib
47、ility Limit (R)Two test results shall bejudged not equivalent if they differ by more than the “R” valuefor that material; “R” is the interval representing the criticaldifference between two test results for the same material,obtained by different operators using different equipment indifferent labor
48、atories.12.1.2.1 Reproducibility limits cannot be determined from asingle-laboratory study.12.1.3 The above terms (repeatability limit and reproduc-ibility limit) are used as specified in Practice E177.12.1.4 Any judgment in accordance with statements 12.1.1and 12.1.2 would normally have an approxim
49、ate 95 % prob-ability of being correct, however the precision statistics ob-tained in this ILS must not be treated as exact mathematicalquantities which are applicable to all circumstances and uses.The limited number of materials tested and the use of data fromjust a single reporting laboratory results guarantees that therewill be times when differences greater than predicted by theILS results will arise, sometimes with considerably greater orsmaller frequency than the 95 % probability limit would imply.The repeatability limit and the repro
