1、Designation: D7308 07 (Reapproved 2012)D7308 17Standard Practice forSample Preparation of Thermoplastic TrafficPavementMarking Materials1This standard is issued under the fixed designation D7308; the number immediately following the designation indicates the year oforiginal adoption or, in the case
2、of revision, the year of last revision. 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 practice covers the proper preparation of test specimens of thermoplastic trafficpavemen
3、t marking materials obtainedto ensure test results are representative of the material being tested.1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.1.3 This standard does not purport to address all of the safety concerns,
4、if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.1.4 This international standard was developed in accordance with internationally recognized
5、 principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D7307 Practice for Sampling
6、of Thermoplastic Traffic Marking Materials3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 thermoplastic traffcpavement marking material, na highly filled 100 % total solids highway marking material that whenheated to a molten state can be extruded or sprayed onto a road surfac
7、e and when cooled forms a solid, durable delineator.4. Summary of Practice4.1 The thermoplastic trafficpavement marking material is prepared for the testing of various physical and chemical propertiesas outlined in the governing specification by melting a sample of the traffic marking material to it
8、s application temperature undercontinuous agitation. Depending upon the requirements of the governing specification the sample can then be exposed to therequired heating time and conditions prior to the preparation of the test specimens or the test specimens may be preparedimmediately after the mate
9、rial has reached application temperatures.temperature.4.2 If required by the governing specification that the sample be subjected to an extended periodsperiod of heating prior to thepreparation of the test specimen in order to determine the effect of heat history upon various physical or chemical pr
10、operties, thesample must be melted down in the prescribed manner outlined in this practice prior to being subjected to such conditions.5. Significance and Use5.1 This practice provides a standard procedure for the preparation of thermoplastic trafficpavement marking material testspecimens prior to t
11、esting for various properties as called for in the governing specification. Specimens that are prepared using thisstandard methodology yield test results that are consistent with the material from which it was sampled. Test results fromspecimens can be used to determine compliance of the thermoplast
12、ic trafficpavement marking material to the specification. This1 This practice is under the jurisdiction of ASTM Committee D01 on Paint and Related Coatings, Materials, and Applications and is the direct responsibility ofSubcommittee D01.44 on Traffic Coatings.Current edition approved June 1, 2012Jun
13、e 1, 2017. Published August 2012June 2017. Originally approved in 2007. Last previous edition approved in 20072012 as D7308 07. 07 (2012). DOI: 10.1520/D7308-07R12.10.1520/D7308-17.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org
14、. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document 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 m
15、ay not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Har
16、bor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1sample preparation guide practice can also be used by manufacturers of these materials to prepare specimens for testing todetermine the uniformity of thermoplastic trafficpavement marking materials from batch to batch.5.2 This p
17、ractice does not address any issues related to specific testing of the thermoplastic pavement marking materials for anyphysical or chemical property.6. Apparatus6.1 Procedure A (Preferred):6.1.1 Stainless Steel 4000 ml Beaker, 150 by 230-mm diameter high. Alternatively an unlined 0.95 L (1 qt) or 3.
18、48 L (1 gal)can may be used depending on the sample size.6.1.2 Heating Mantle of sufficient size. Note that aluminum foil may be used to serve as somewhat of a gasket if an unlinedmetal can is to be used in the heating mantle in place of the stainless steel beaker.6.1.3 Temperature Indicator.6.1.4 T
19、hermocouple, iron.6.1.5 Mechanical Stirrer, capable of stirring. The stirrer should consist of two impellers with a diameter of approximately 63.5mm mounted on a 7.95-mm diameter shaft of sufficient length.6.1.6 Aluminum Lid to cover the top of the container with a slot to clear the shaft of the mec
20、hanical stirrer and the thermocouple.6.1.7 Stainless Steel Ladles with a pouring spout, 60-ml capacity.6.1.8 Tachometer to measure shaft speed of the mechanical mixer.6.2 Procedure B (Alternate):6.2.1 Hot Plate with a maximum temperature setting of approximately 550C and with sufficient top plate su
21、rface area as toextend beyond the surface area of the bottom of the container to be used for melting the sample.6.2.2 Unlined Cans, 0.95 L (1 qt) or 3.48 L (1 gal) as required by the specified sample size.6.2.3 Spatula.6.2.4 Gloves.6.2.5 Tongs.6.2.6 Thermometer (capable of measuring up to 450F).7. H
22、azards7.1 Following this guidepractice requires one to work with materials that are heated to very high temperatures (350 to 450F).Care must be taken to prevent accidental burns.7.2 Consult the MSDSSDS for the thermoplastic pavement marking material being tested to understand the proper way tohandle
23、 any accidental burns.7.3 Wear protective clothing, thermal resistant gloves, and eye protection.8. Procedure8.1 Obtaining a representative sample is critical in determining the suitability of the material being tested in meeting therequired specification or in determining the batch-to-batch consist
24、ency of the thermoplastic trafficpavement marking material.Obtain a representative sample by following Practice D7307. The size of the sample being tested may vary depending upon theobjective of the person conducting the test, varying from an approximate 0.95 L (1 qt) or 1 000 g sample to a 3.48 L (
25、1 gal) or4 000 g sample. An approximate 0.95 L (1 qt) or 1 000 g sample should be the minimum sample size tested.8.2 Procedure A (Preferred):8.2.1 This procedure covers the melting of thermoplastic pavement marking material using a heating mantle and a mechanicalstirrer. This procedure simulates clo
26、sely what occurs in the actual use of this material.8.2.1.1 Set up the apparatus as shown in Fig. 1. Wire the heating mantle power cord to the temperature indicator controller inaccordance with the manufactures instructions. Mount the controller-indicator in a panel that can be wall mounted to keep
27、the unitaway from heat, dirt, and vibrations. When the unit is ready for operation, make a test melt in order to set the proportional bandand other adjustment to give a controlled temperature of 218 6 1C (425 6 2F).2F), or to an alternate temperature as called forin the governing specification.8.2.1
28、.2 Place one-third to one-half of the granular sample into the container residing in the heating mantle. Attach the stirringshaft to the mechanical stirrer.8.2.1.3 Turn on the power to the heating mantle and the controller. Start the variable speed mechanical stirrer when thethermoplastic material h
29、as softened sufficiently.8.2.1.4 Slowly add the remainder of the granular sample at a rate so as to maintain continuous stirring.8.2.1.5 After the entire granular sample has been added to the container set the speed of the mechanical stirrer with thetachometer to a speed of about 100 rpm. Cover the
30、container using the aluminum lid, positioning the lid such that it clears the mixershaft and the thermocouple.D7308 1728.2.1.6 Allow the material to heat and mix until it reaches a temperature of approximately 425F (218 6 1C).218 6 1C (4256 2F), or to an alternate temperature as called for in the go
31、verning specification.FIG. 1 Thermoplastic Melter ApparatusD7308 1738.2.1.7 Using a 60 ml (2 oz.) ladle remove some of the molten thermoplastic material while under agitation and prepare the testspecimens as required by the specific test method that is to be used.8.2.1.8 If required by the specifica
32、tion, the sample can be maintained at the required temperature for the required period of timeprior to the preparation of the test specimens.8.3 Procedure B (Optional):8.3.1 This option covers the melting of thermoplastic pavement marking material using a hot plate and manual stirring.8.3.1.1 Place
33、an empty can of sufficient size to melt the sample on the hot plate set on high. The surface of the hotplate shouldextend beyond the area covered by the bottom surface of the can. Failure to use a hot plate with sufficient top plate area can causethe top plate to crack.8.3.1.2 Add approximately one-
34、fifth of the granular thermoplastic into the container and allow the material to heat, stirringregularly with a spatula.8.3.1.3 Once the material is molten continue to add dry material incrementally with constant agitation in order to keep thematerial molten and avoid scorching.8.3.1.4 After all of
35、the dry material has been added continue to stir the material with the spatula checking the temperatureregularly with a thermometer.8.3.1.5 When the material reaches 425F, maintain the temperature between 400 and 425 degrees for approximately 10 min withconstant stirring.8.3.1.6 Remove the material
36、from the hotplate and prepare the test specimens as required by the specific test methods that areto be used.8.3.1.7 If required by the specification, the sample can be maintained at the required temperature for the required period of timeprior to the preparation of the test specimens. If the sample
37、 is maintained in a temperature controlled oven without agitation thesample should be well stirred to ensure material homogeneity prior to pouring the test specimens.9. Keywords9.1 sample preparation; thermoplastic trafficpavement markingsASTM International takes no position respecting the validity
38、of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject t
39、o revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn.Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters.
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