1、Standard Method of Test for Producing Draw Down Panels and Measuring the Coefficient of Retroreflected Luminance (RL) of Pavement Markings in a Laboratory Panel AASHTO Designation: TP 130-181Technical Section: 4c, Markings and Coatings Release: Group 2 (June) American Association of State Highway an
2、d Transportation Officials 444 North Capitol Street N.W., Suite 249 Washington, D.C. 20001 TS-4c TP 130-1 AASHTO Standard Method of Test for Producing Draw Down Panels and Measuring the Coefficient of Retroreflected Luminance (RL) of Pavement Markings in a Laboratory Panel AASHTO Designation: TP 130
3、-181Technical Section: 4c, Markings and Coatings Release: Group 2 (June) 1. SCOPE 1.1. This test procedure is used to determine the retroreflectivity of M 247 Type I highway beads. Beads are dropped on top of a uniform thickness of paint and retroreflectivity is determined with a reflectometer. 1.2.
4、 The values stated in English units are generally to be regarded as the standard with metric units being in parentheses. Cases exist where only one unit convention is being used and should be considered as the only convention to be used. 1.3. This standard may involve hazardous materials, operations
5、, 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 procedure to establish appropriate safety and health practices and to determine the applicability of regulatory limitations prior to use. 2. REF
6、ERENCED DOCUMENTS 2.1. AASHTO Standards: M 247, Glass Beads Used in Pavement Markings T 346, Glass Beads Used in Pavement Markings MP 24, Waterborne White and Yellow Traffic Paints 2.2. ASTM Standards: D8008, Standard Practice for Representative Field Sampling of Traffic Paints E1710, Test Method fo
7、r Measurement of Retroreflective Pavement Marking Materials with CEN-Prescribed Geometry Using a Portable Retroreflectometer 2018 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-4c TP 130-2 AASHTO 3. TERM
8、INOLOGY 3.1. coefficient of retroreflected luminance, RLthe ratio of the luminance, L, of a projected surface to the normal illuminance, E, at the surface on a plane normal to the incident light, expressed in candelas per square meter per lux (cdm-2)/lx. Because of the low luminance of pavement mark
9、ings, the units commonly used are millicandelas per square meter per lux (mcdm2)/lx. 3.2. portable retroreflectometeran instrument that can be used in the field or laboratory for measuring the coefficient of retroreflected luminance, RL. 4. SUMMARY OF TEST METHOD 4.1. This test procedure is used to
10、predict the retroreflectivity of M 247, Type I glass beads in waterborne paint using a laboratory simulation of a field striping operation. Measured quantities of glass beads are dropped on top of a repeatable, uniform thickness of paint on top of a glass panel. When the paint is dry (after 24 hours
11、), the retroreflectivity is measured using a 30 m geometry portable retroreflectometer. 5. SIGNIFICANCE AND USE 5.1. One of the characteristics of a pavement marking is the coefficient of retro reflected luminance, RL.Under identical conditions of headlight illumination and driver viewing, larger va
12、lues of RLcorrespond to higher levels of visual performance at corresponding geometry. 6. APPARATUS 6.1. For waterborne paint, water for clean up; 6.2. 4 in. draw down bar; thickness capability from 15-30 mils (375-750 microns); 6.3. Flat substrate 6 by 24 in. made of 1/8in. glass, aluminum, or slat
13、e; 6.4. Support fixture to hold substrate firmly in place during draw down; 6.5. Balance to 0.01 g accuracy; 6.6. Splitters to obtain representative glass bead sample (large 16:1, small 1:1); 6.7. Weighing dishes and containers for beads and paint; 6.8. Bead drop box (see Figure 1) with dimensions o
14、f approximately 51/2by 191/2in. by 14 in. (producing a 4 by 18 in. stripe) filled with 10 layers of 1/4in. screening spaced 1 in. apart, with support bar to hold beads in swivel mounted on top; 2018 by the American Association of State Highway and Transportation Officials. All rights reserved. Dupli
15、cation is a violation of applicable law.TS-4c TP 130-3 AASHTO Figure 1Bead Drop Box 6.9. Reflectometer, 30 m geometry based on retroreflective measurements made with portable hand-operated instruments in compliance with ASTM E1710; 6.10. Paint film thickness gauge, 5-30 mil (125-750 microns); and 6.
16、11. Magnifying glass to check glass bead embedment. 7. SAMPLING 7.1. A representative sample of glass beads meeting the requirements of M 247, Type 1, should be taken following T 346 procedures. The sampling shall be random in the following ratios: 100 lb (45 kg) of sample (in full bags) per 10,000
17、lb (4,535 kg) shipped. Upon arrival, material shall be reduced in a sample splitter to a size of approximately 2.2 lb (1 kg). 8. CALIBRATION 8.1. The draw down procedure must be calibrated to ensure the correct thickness of paint is applied. The retroreflectometer must be calibrated in accordance wi
18、th the manufacturers instructions. The retroreflectivity is very dependent on the paint formula in addition to the glass bead quality. Use a control paint to compare glass bead retroreflectivity (Sherwin Williams TM2152 White). Note 1Use of this specific control product was chosen by NCHRP research
19、team to minimize the test variables and compare testing and final retroreflection performance. Users could consider alternate control traffic paints to suit their specific needs. 8.2. Paint Thickness Calibration Procedure: 8.2.1. Choose a draw down bar opening to achieve 15-mil wet film of paint thi
20、ckness. 8.2.2. Pour enough paint into the draw down bar to ensure coverage over the full 18 in. panel, approximately 100 mil (Figure 2). 2018 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-4c TP 130-4 AA
21、SHTO Figure 2Paint Draw Down Process 8.2.3. Draw the draw down blade in a smooth manner down the plate. 8.2.4. Immediately place the draw down blade into water to make clean up easier. 8.2.5. Stick the paint film thickness gauge into the wet paint and read the paint thickness. 8.2.6. Use a different
22、 mil thickness accordingly (if 30 mil open yields 20 mil wet, use a smaller mil opening such as 25 mil to achieve the desired 15 mil wet paint). 8.2.7. Repeat previous steps to check the resulting wet paint thickness. 8.3. Retroreflectometer Calibration: 8.3.1. Follow manufacturer recommendations. 9
23、. PROCEDURE 9.1. Obtain a sufficient quantity of glass beads meeting the requirements of M 247, Type 1 and sampled in accordance with sampling procedures in T 346. Use a large splitter to reduce the glass beads to a 2.2 lb (1 kg) sample size and then a small splitter to a sample size required for th
24、e test (Figure 3). Split sample to approximate weight for area of paint coverage on the substrate. For example, with a 4 in. by 18 in. stripe at 15 mil with an application rate of 8 lb of beads per gal of paint, the bead sample size would be 17 g. This rate is equivalent to 0.236 g of beads per 1 in
25、.2of paint. 9.2. Pour beads from weighing dish evenly onto the bead support bar on top of the drop box (see Figure 4). 2018 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-4c TP 130-5 AASHTO Figure 3Large
26、 Bead Splitter 16:1 (Left) and Small Bead Splitter 1:1 (Right) Figure 4Drop Box Bead Support Bar 9.3. With panel in support fixture, place the 30 mil (750 micron) edge of the draw down bar on top of the panel. (This should produce a 15 mil wet thickness. Check with thickness gauge.) 9.4. Weigh out w
27、aterborne paint required. Stir paint thoroughly and pour into the draw down bar. Note 2Steps in Sections 9.4 through 9.7 must be completed within 20 s to avoid having the paint change viscosity on curing. 9.5. Obtain sufficient quantity of waterborne paint meeting the requirements of MP 24 to perfor
28、m the test. If necessary, obtain the waterborne paint by sampling in accordance with ASTM D8008. Pull the draw down bar across the length of the panel at a consistent speed to spread a uniform layer of paint. Place a paper towel at the end of the panel to catch excess paint. A straight edge along th
29、e length of the panel insures properly applied paint. 9.6. Immediately after sliding the draw down bar and after the paper towel is removed from the support fixture, place the bead drop box over the panel and dump the beads. 2018 by the American Association of State Highway and Transportation Offici
30、als. All rights reserved. Duplication is a violation of applicable law.TS-4c TP 130-6 AASHTO 9.7. Lift the bead drop box a few inches directly above the panel and bump it to dislodge any retained beads. Clean draw down bar with water immediately. Create a total of three panels in similar fashion. 9.
31、8. Store panels in horizontal position for 24 h. 9.9. After 24 h, use a soft bristle brush to remove any loose beads on the surface of the panels using three light strokes in one direction. Check embedment with a magnifying glass to make sure paint is covering about 60 percent of the bead height. 9.
32、10. Determine retroreflectivity (using the appropriate instrument instructions) by taking five randomly chosen readings in separate locations on each panel in the direction in which the paint was applied. Make sure the reflectometer and panel are on a flat, even surface. 9.11. Calculate average of t
33、he readings as well as the average of readings on all three panels and report. 10. REPORT 10.1. The report shall include the following information: 10.1.1. Date; 10.1.2. Technician name; 10.1.3. Manufacturer name, product name, and lot number of waterborne paint used in test; 10.1.4. Manufacturer na
34、me, product name, and lot number of glass beads used in test; 10.1.5. Bead supplier, plant; 10.1.6. Weight of glass beads used in draw down; 10.1.7. Paint thickness desired; 10.1.8. Draw down blade used; 10.1.9. Time of draw down production; 10.1.10. Temperature; 10.1.11. Humidity; 10.1.12. Time of
35、retroreflectivity readings; 10.1.13. Average retroreflectivity reading, (mcd*mA2 )/lux; and 10.1.14. Observationsbead embedment and coverage, lumps in paint, uniformity. 11. KEYWORDS 11.1. Glass beads; pavement markings; retroreflection; traffic paint. 2018 by the American Association of State Highw
36、ay and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-4c TP 130-7 AASHTO APPENDIXES (Nonmandatory Information) X1. FACTORS THAT MAY AFFECT MEASUREMENTS X1.1. Over-embedment of glass beads will lower retroreflectivity. X1.2. Glass beads falling out of p
37、aint will lower retroreflectivity. X1.3. Paint quality will affect retroreflectivity. X1.4. Adding water to paint will lower retroreflectivity. X1.5. Lumps in paint will result in uneven paint thickness and impact embedment. X1.6. Laboratory environment (the relationships developed using this protoc
38、ol are based on a temperature range of 68F to 74F and a relative humidity range of 32 to 50 percent). X2. WORKING WITH WATERBORNE TRAFFIC PAINT X2.1. Paint must be covered at all times, minimizing the time the container is open to prevent paint skinning on the inside cover of the paint can. X2.2. Wa
39、terborne paint is designed to skin and dry to the touch very quickly. This necessitates working very quickly when performing this test to allow the glass beads to embed properly in the paint. If the beads are not dropped before the paint skins over, poor glass bead embedment will result. X2.3. Paint
40、 settles quite quickly over time and has a shelf life of only six months. X2.4. Paint should be stirred, never shaken. (Shaking the paint knocks dried lumps off the top of the paint can and results in lumps in the paint.) X2.5. Paint should be screened to remove lumps. 1This provisional standard was first published in 2018. 2018 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.
