1、Standard Method of Test for Glass Beads Used in Pavement Markings AASHTO Designation: T 346-131American Association of State Highway and Transportation Officials 444 North Capitol Street N.W., Suite 249 Washington, D.C. 20001 TS-4c T 346-1 AASHTO Standard Method of Test for Glass Beads Used in Pavem
2、ent Markings AASHTO Designation: T 346-1311. SCOPE 1.1. The procedures for testing glass beads used in traffic markings are described in this method. This includes the method for obtaining a representative test sample, preparation of the test specimens, and performing the specified tests. 1.2. This
3、test method is divided into the following parts: 1.2.1. Section 3, Sampling Glass Beads During Production; 1.2.2. Section 4, Sampling Shipments of Glass Beads Vertically from Bulk Containers; 1.2.3. Section 5, Gradation; 1.2.4. Section 6, Roundness; 1.2.5. Section 7, Refractive Index; 1.2.6. Section
4、 8, Flow Characteristics TestReferee Method; 1.2.7. Section 9, Moisture Resistant Coating TestReferee Method; 1.2.8. Section 10, Flotation TestReferee Method; 1.2.9. Section 11, Adherence Coating Oven TestReferee Method; 1.2.10. Section 12, Alternative Flotation TestAs Permitted by Purchasing Agency
5、; 1.2.11. Section 13, Alternative Moisture Resistance TestAs Permitted by Purchasing Agency; and 1.2.12. Section 14, Alternative Adherence TestAs Permitted by Purchasing Agency. 1.3. The values stated in SI units are to be regarded as the standard. 1.4. This standard may involve hazardous materials,
6、 operations, and equipment. This standard does not purport to address all of the safety concerns associated with its use. It is the responsibility of the user of this standard to consult and establish appropriate safety and health practices and determine the applicability of regulatory limitations p
7、rior to use. 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-4c T 346-2 AASHTO 2. REFERENCED DOCUMENTS 2.1. AASHTO Standard: PP 74, Determination of Size and Roundness of Glass Beads Used in Traffic M
8、arkings by Means of Computerized Optical Method 2.2. ASTM Standards: C1648, Standard Guide for Choosing a Method for Determining the Index of Refraction and Dispersion of Glass D75/D75M, Standard Practice for Sampling Aggregates D1155, Standard Test Method for Roundness of Glass Spheres D1214, Stand
9、ard Test Method for Sieve Analysis of Glass Spheres E105, Standard Practice for Probability Sampling of Materials E1617, Standard Practice for Reporting Particle Size Characterization Data E1994, Standard Practice for Use of Process Oriented AOQL and LTPD Sampling Plans 2.3. Other Standards: ANSI/AS
10、Q Z1.4, Sampling Procedures and Tables for Inspection by Attributes ANSI/ASQ Z1.9, Sampling Procedures and Tables for Inspection by Variables for Percent Nonconforming 3. SAMPLING GLASS BEADS DURING PRODUCTION 3.1. The sampling shall be random in the following ratios: 45 kg (100 lb) of sample (in fu
11、ll bags) per 4535 kg (10,000 lb). ASQ Z1.4 and Z1.9 may be used to monitor the quality of the product so that it meets the requirement of the applicable detail specification. The supplier shall state in a Declaration of Conformity the sampling plans and test methods used. Accumulation of large quant
12、ities during the production sampling process shall be reduced to appropriate size by use of a splitter. Note 1The use of splitters to reduce the large sample of glass beads to the appropriate testing quantity is critical in minimizing sampling errors. 4. SAMPLING SHIPMENTS OF GLASS BEADS VERTICALLY
13、FROM BULK CONTAINERS 4.1. Sample from 200-L (55-gal) drums or other bulk containers utilizing a sample probe, as described in Figure 1, approximately 1.2 m (48 in.) long 0.6 m (24 in.) long for 22.5-kg (50-lb) pails or sacks. 2015 by the American Association of State Highway and Transportation Offic
14、ials.All rights reserved. Duplication is a violation of applicable law.TS-4c T 346-3 AASHTO Figure 1Sample Probe 4.1.1. Prior to obtaining the sample, to avoid contamination, make certain the inside of the probe is clean by pulling the rubber hose from the outer tube and checking for any material on
15、 both the rubber hose and inside the probe. 4.1.2. Place the rubber hose back into the probe. 4.1.3. Insert the probe vertically, with rubber hose inserted, slowly into one corner of the bulk container until it reaches the bottom. 4.1.4. Slowly remove the rubber hose from the probe allowing the mate
16、rial to flow into the probe through the bottom holes first. Slightly shake the probe as the rubber hose is removed in order to allow as much material as possible to flow into the probe. 4.1.5. Slowly remove the probe from the container and pour the sampled material into a sample collection bag. 4.1.
17、6. Clean the probe and rubber hose of all material. 4.1.7. Repeat steps in Sections 4.1.2 through 4.1.5, sampling from three other corners (or locations) and the center of the container. 4.1.8. Reduce the aggregate of the five sampled locations to an appropriate quantity by use of a regular or mini
18、1:1 splitter. PROBE OR SAMPLE THIEFTOP VIEW OF BOXProbe Sampling Sequence forRetroreflective Glass Beads48 in.ABEDC2 in.(Typ.)1/2-in. Hose, 50 in. long5/16-in. Dia. Holes(17 Total)Stainless Steel Rod, I.D.11/16in.,Wall Thickness,1/8in.31/2in. 2015 by the American Association of State Highway and Tra
19、nsportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-4c T 346-4 AASHTO 5. GRADATION 5.1. GradationThe method of test utilized shall be as directed by the specifying agency. 5.1.1. Method AASTM D1214, Hand Sieve Method. 5.1.2. Method BPP 74, Computerized Optical
20、Method. 6. ROUNDNESS 6.1. RoundnessThe method of test utilized shall be as directed by the specifying agency. 6.1.1. Method AASTM D1155. 6.1.2. Method BPP 74, Computerized Optical Method. 7. REFRACTIVE INDEX 7.1. Refractive Index shall be tested by a liquid immersion method (ASTM C1648, Becke Line M
21、ethod or equivalent) at a temperature of 25 5C (77 9F). 8. FLOW CHARACTERISTICS TESTREFEREE METHOD 8.1. A 100-g sample of beads is placed in a Corning 3140 crystallizing dish (or equivalent), 100-mm diameter by 50-mm depth. Place the dish in a Corning 3080 Desiccator (or equivalent), 250-mm inside d
22、iameter by 330-mm overall height and 130-mm chamber depth, which shall be filled with a sulfuric acid-water solution having a specific gravity of 1.10 (approximately 94 percent humidity) to a point 25.4 mm below the top of a size 5 Coors 60003 Desiccator Plate (or equivalent). The sample shall remai
23、n in the covered Desiccator at 25 5C for 4 h. Remove the sample from the Desiccator and transfer the beads to a metal pan. The beads shall flow without stoppage when poured slowly through a standard glass funnel (Corning 6120 or equivalent), 127-mm diameter, 102-mm stem length, and 11-mm stem inside
24、 diameter (Note 2). Note 2The test operations should be performed immediately upon removal of the beads from the Desiccator. 9. MOISTURE RESISTANT COATING TESTREFEREE METHOD 9.1. A 100-g sample of beads is placed in a 600-mL beaker. With the beaker held at about a 45-degree angle, 100 mL of distille
25、d water is slowly added to the beaker. The water is carefully poured down the side of the tilted beaker. The beads are to remain undisturbed. The beaker is allowed to stand, undisturbed, for 5 min. At the end of the standing time, the water is carefully poured from the beaker. It may be necessary to
26、 slightly rotate the beaker to avoid trapping pockets of water. Holding the beaker at the “pour angle,” the beads are transferred to a clean, dry 600-mL beaker. A thin, even layer of beads may coat the inside of the original beaker. The second beaker is allowed to stand, undisturbed, for 5 min. At t
27、he end of the standing time, the beads are slowly poured into a standard glass funnel (Corning 6120 or equivalent), 127 mm in diameter, 102-mm stem length, and 11-mm stem inside diameter. The beads should flow through the funnel stem without stopping. Slight initial agitation to start the flow of be
28、ads through the funnel is permissible. 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-4c T 346-5 AASHTO 10. FLOTATION TESTREFEREE METHOD 10.1. Determine the mass of approximately 1 g to the nearest 0
29、.0005 g. Evenly distribute beads into a clean, standard 100-mm glass Petri dish previously weighed to the nearest 0.0005 g. The dish is vibrated slightly to attain as near as possible a monolayer of beads. Xylene, C.P. Grade, is introduced at one side of the dish at a rate of 10 to 15 mL/min from a
30、burette until 30 mL has been added. The floating beads are then carefully drawn off by suction through a suitably constricted delivery tube connected to a receiving flask. Excess xylene is drawn off so that no remaining beads are lost and the dish is dried in an oven at 110 5C. After cooling to room
31、 temperature, the dish is weighed and the percentage of floating beads is calculated. 11. ADHERENCE COATING OVEN TESTREFEREE METHOD 11.1. Prepare a solution by weighing 0.2 g of dansyl chloride and dissolving in 25 mL of acetone. (See Note 3.) This solution can be used for several tests during the d
32、ay, but must be kept refrigerated in a closed dark container between uses. Make a fresh solution daily. WarningDansyl chloride is hazardous. Do not allow skin contact or touch the beads after testing. Note 3Dansyl chloride tests for the presence of amino functional groups, which are present in most
33、common adhesion coatings. If the supplier is using alternate adhesion chemistry, a comparably simple test must be supplied. Dansyl chloride will oxidize on prolonged contact with air and light. Solutions should be stored in a dark, brown glass jar. Fresh solutions are a pale yellow-green. Unusable s
34、tale solutions are yellow-brown. 11.2. Weigh 10 g of beads and place in aluminum trays. Saturate the glass bead sample with the dansyl chloride solution using an eyedropper. Dry the beads in an oven at 60C (140F) for 15 min. Beads will be yellow and agglomerated. Using a Buchner funnel with new filt
35、er paper and suction applied, place the beads in the funnel and pour 100 mL of acetone over them. Remove the beads from the funnel, and again place in aluminum trays. Dry the beads in the oven until free flowing. Place the beads on glass filter paper and inspect them under ultraviolet light. Inspect
36、ion must be in a dark room. A yellow-green fluorescence will be observed if adherence coating is present. (See Notes 3 and 4.) If all beads have a yellow-green fluorescence with the oven test, the beads are properly coated with adherence coating. If some or no beads have a yellow-green fluorescence,
37、 then this is cause for rejection. Note 4Fluorescence is proportional to the intensity of the incident UV light. Long-wave UV lamps designed for quality control, industrial inspection, and nondestructive testing are typically 100 W. Portable lamps with 6- or 8-W bulbs will show much less fluorescenc
38、e on the same samples. Longwave UV bulbs emit at 365-nm wavelength. Shortwave UV lamps, 254 or 302 nm, and low-watt penlight lamps are not sufficient for this test. 12. ALTERNATIVE FLOTATION TESTAS PERMITTED BY PURCHASING AGENCY 12.1. A 15- to 20-g sample of beads is placed in a 60-mL (2-oz) aluminu
39、m weighing dish, 57-mm inside diameter by 16-mm depth. The filled dish should be placed on a flat surface and shaken lightly so that the beads present a flat surface. Carefully place small drops of hexadecane approximately 5 mm (0.187 in.) in diameter or 0.05-mL volume on the test beads in three loc
40、ations so that the drops are not touching. The dish should be left flat and the drops should be put in the center of the dish. Do not touch the beads with the dropper tip. A positive test for the presence of coating occurs if all three drops applied show clear, well-rounded appearance with high cont
41、act angle, i.e., the test liquid beads up. A negative test for coating shows the loss of contact angle of the drop, i.e., if wetting of the beads as evidenced by a darkening of the surface or sinking of the drop into the surface or bead interface occurs within 2 min 10 s. 2015 by the American Associ
42、ation of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-4c T 346-6 AASHTO 13. ALTERNATIVE MOISTURE RESISTANT COATING TESTAS PERMITTED BY PURCHASING AGENCY 13.1. This test is identical to the Alternative Flotation test in Section 12 exc
43、ept that it is performed with three distilled water drops instead of hexadecane. 14. ALTERNATIVE ADHERENCE TESTAS PERMITTED BY PURCHASING AGENCY 14.1. The test in Section 11 is performed with the following exceptions: 14.2. One eyedropper full (1.0 mL) of 0.02 percent by weight of dansyl chloride (5
44、-dimethylaminonaphthalene-1-sulfonyl chloride) solution in acetone is dropped around the center of the 10 g of beads. Do not disturb or mix the beads after wetting. After 30 min, a positive test for the presence of coating occurs if the wetting area shows clear fluorescence, a bright green to blue g
45、low, under strong, long UV light (365 nm) against a dark background in a darkened room or stray, light-free enclosure. A negative test for coating occurs if the wetted surface of the beads shows no fluorescence. The reaction may be speeded by heating the tested sample to 60 5C (140 9F) for 5 min. It
46、 is best practice to use heat and simultaneously test the sample alongside beads known to have no adhesion coating. A positive presence of coating should be clearly visible in comparison to the beads with no coating. 1Formerly AASHTO Provisional Standard TP 97. First published as a full standard in 2012. 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.
