AASHTO Product Evaluation List: EcoStrate Sign Substrate Evaluation (ES1)

Transcription

1 AASHTO Product Evaluation List: EcoStrate Sign Substrate Evaluation (ES1) Final report prepared by Adam M. Pike, P.E. Associate Research Engineer TEXAS A&M TRANSPORTATION INSTITUTE College Station, Texas Report Prepared for the American Association of State Highway and Transportation Officials (AASHTO) Product Evaluation Program July 2015

2 DISCLAIMER This evaluation was performed by the Texas A&M Transportation Institute. The contents of this report reflect the views of the authors, who are responsible for the facts and the accuracy of the data presented herein. The contents do not necessarily reflect the official view or policies of any State, Federal agency, or AASHTO. This report does not constitute a standard, specification, or regulation. The Texas A&M Transportation Institute does not endorse products or manufacturers. Trade or manufacturers names appear herein solely because they are considered essential to the object of this report. Page ii

3 TABLE OF CONTENTS List of Figures... iv List of Tables... v Chapter 1: Project Overview... 1 Chapter 2: Flexural, Tensile, Shear Testing... 2 Flexural Testing... 2 Tensile Testing... 4 Shear Strength Testing... 5 Chapter 3: Flexural, Tensile, Shear Testing After Accelerated Weathering... 7 Flexural Testing... 9 Tensile Testing... 9 Shear Strength Testing Before and After Comparison Chapter 4: Adhesion Testing Adhesion Testing at Ambient Temperatures Adhesion Testing at Various Temperatures Adhesion Testing at Ambient Temperature after Accelerated Weathering Chapter 5: Free Vibration Testing Free Vibration Testing Setup and Calculations Free Vibration Testing Results Chapter 6: Projectile Impact Testing Impact Testing Setup Impact Testing at Ambient Temperature Impact Testing at 100 F Impact Testing at 145 F Impact Testing at 0 F Impact Testing at 40 F Impact Testing at Ambient Temperature after Accelerated Weathering Chapter 7: Findings Discussion of Findings Recommended Testing References Page Page iii

4 LIST OF FIGURES Figure 1. 3-Point Bending, Flexural Testing Device Figure 2. Samples after Flexural Testing Figure 3. Tensile Testing Device Figure 4. Samples after Tensile Testing Figure 5. Shear Testing Device Figure 6. Samples after Shear Testing Figure 7. Samples prior to Starting the Accelerated Weathering Figure 8. Samples after Accelerated Weathering Figure 9. Samples after Flexural Testing Figure 10. Samples after Tensile Testing Figure 11. Samples after Shear Testing Figure 12. Pull-off Tester Figure 13. Adhesion Test at Figure 14. EcoStrate 1 Substrate Samples Figure 15. Aluminum Substrate Samples Figure 16. Free Vibration Test Setup Figure Sign Mounted to Pole prior to Impact Testing Figure 18. Impact Testing Setup Figure 19. Holding Box with Temperature Sensor for Conditioned Materials Figure 20. EcoStrate 1 Back of Substrate Ambient temp (9mm on Top,.22 cal on Bottom) Figure 21. EcoStrate 1 Back of Substrate at 40 F (.22 cal on Top, 9 mm on Bottom) Figure 22. EcoStrate 1, Sample on Pole Comparison Page iv

5 LIST OF TABLES Table 1. ASTM Standard Test Methods Used Table 2. Flexural Testing Results Table 3. Tensile Testing Results Table 4. Shear Testing Results... 6 Table 5. Flexural Testing Results Table 6. Tensile Testing Results Table 7. Shear Testing Results Table 8. Before and After Table 9. Sheeting Types to Evaluate Table 10. Adhesion Testing Results at Ambient Temperature Table 11. Adhesion Testing Failure Mode at Ambient Temperature Table 12. Adhesion Testing Results at Various Temperatures Table 13. Adhesion Testing Failure Mode at Various Temperatures Table 14. Adhesion Testing Results after Accelerated Weathering at Ambient Temperature Table 15. Damping Coefficient Results at Various Temperatures Table 16. Impact Testing Results at Ambient Temperature Table 17. Impact Testing Results at 100 F Table 18. Impact Testing Results at 145 F Table 19. Impact Testing Results at 0 F Table 20. Impact Testing Results at 40 F Table 21. Impact Testing Results after Accelerated Weathering Page v

6 CHAPTER 1: PROJECT OVERVIEW This report describes the evaluation of the EcoStrate sign substrate material for the American Association of State Highway and Transportation Officials (AASHTO) Product Evaluation List Council (APEL Council). The EcoStrate sign substrate is a composite made from recycled electronic waste plastics and textile carpet waste. The Texas A&M Transportation Institute (TTI) evaluation team worked with the APEL Council to identify the properties of the substrate material to test and how the tests were to be conducted. In accordance with the APEL program no field evaluations took place, solely accelerated laboratory testing. The main areas to evaluate with the testing were the strength of the material (flexural, tensile, shear), the ability of sign sheeting material to adhere to the substrate across a range of temperatures, the ability of the substrate material to withstand wind forces across a range of temperatures, and the ability of the material to withstand being shot with a gun across a range of temperatures. The impact of weathering (solar radiation, etc.) was also a concern. The TTI team developed the testing protocol to address these testing areas. To compare performance levels, an aluminum substrate was included in some of the testing, and in areas where aluminum was not included, past evaluation results (1, 2) or known material properties can serve as comparison data. The EcoStrate substrate material was received by the TTI team and was referred to as EcoStrate 1 (ES1). ES1 is a composite substrate material comprised of waste post-consumer carpet and fibers with recycled plastic ewaste. ES1 was identified with black permanent marker. The substrate material was colored so that when smaller samples were cut from the larger pieces that the color identification would still be on all cut pieces. The following chapters of this report describe the testing conducted and the results of the testing. Each chapter covers a separate area of the testing. The final chapter summarizes the findings and provides recommended tests that State DOTs may use with their quality assurance programs. Page 1

7 CHAPTER 2: FLEXURAL, TENSILE, SHEAR TESTING This chapter describes the flexural, tensile, and shear testing that took place on the sample substrate materials. These tests are typically performed on materials to verify the materials meet minimum required values. There are not established minimum required values for sign sheeting substrates. The units used throughout the testing are in pounds per square inch (psi), 1 psi = MPa. All testing was conducted in accordance with established ASTM standard test methods. Table 1 provides the specific ASTM standard test methods used. All testing was conducted in ambient lab conditions. Only the substrate materials were tested; no sign sheeting material was present on the substrates. The samples used in the testing were cut from the larger pieces that were sent to TTI for testing. For each test, five samples were tested. Table 1. ASTM Standard Test Methods Used. ASTM Designation Description D Flexural Properties of Plastics D Tensile Properties of Plastics D Shear Strength of Plastics FLEXURAL TESTING Figure 1 provides an image of the flexural testing 3-point bending setup. Figure 2 shows the ES1 samples after testing. Table 2 provides the resulting data from the testing. The testing resulted in a flexural modulus value of approximately 333,000 psi. The flexural strength at break was approximately 6900 psi. Page 2

8 Figure 1. 3-Point Bending, Flexural Testing Device. Figure 2. Samples after Flexural Testing. Page 3

9 Table 2. Flexural Testing Results. ASTM D Flexural Testing Substrate Material Flexural Strength at Break (psi) Sample 1 Sample 2 Sample 3 Sample 4 Sample 5 Average Flexural Strength at Break (psi) Average Flexural Modulus (10 3 psi) ES TENSILE TESTING Figure 3 shows an image of the tensile testing setup. Figure 4 shows the ES1 samples after testing. Table 3 provides the resulting data from the testing. The testing resulted in a tensile modulus value of approximately 373,000 psi. The tensile strength at break was approximately 3600 psi. Figure 3. Tensile Testing Device. Page 4

10 Figure 4. Samples after Tensile Testing. Table 3. Tensile Testing Results. Substrate Material Sample 1 ASTM D Tensile Testing Tensile Strength at Break (psi) Sample 2 Sample 3 Sample 4 Sample 5 Average Tensile Strength at Break (psi) Average Tensile Elongation at Break (%) Average Tensile Modulus Young's (10 3 psi) ES SHEAR STRENGTH TESTING Figure 5 shows an image of the shear testing setup. Figure 6 shows the ES1 samples after testing. Table 4 provides the resulting data from the testing. The testing resulted in a shear strength value of approximately 5700 psi. Page 5

11 Figure 5. Shear Testing Device. Figure 6. Samples after Shear Testing. Table 4. Shear Testing Results. ASTM D Shear Strength Testing Substrate Material Shear Strength (psi) Sample 1 Sample 2 Sample 3 Sample 4 Sample 5 Average Shear Strength (psi) ES Page 6

12 CHAPTER 3: FLEXURAL, TENSILE, SHEAR TESTING AFTER ACCELERATED WEATHERING This chapter describes the flexural, tensile, and shear testing that took place on the sample substrate materials after they had been exposed to artificial accelerated weathering. These tests were conducted to determine if the artificial accelerated weathering would impact the properties of the substrate material. The artificial accelerated weathering was conducted according to ASTM D , Standard Specification for Retroreflective Sheeting for Traffic Control. ASTM D is a specification for sign sheeting material that has an option for exposing the sign sheeting material to artificial accelerated weathering to test the material s ability to withstand solar radiation and moisture. The evaluation team felt that subjecting the sign substrate material to the same test would be an effective means of evaluating the substrate material s ability to handle an accelerated weathering condition. The artificial accelerated weathering method outlined in ASTM D uses a xenon arc weatherometer to provide accelerated weathering on sign sheeting materials. The xenon arc weatherometer simulates direct exposure to solar radiation at approximately 145 F and also uses a water spray apparatus to simulate moisture on the materials. The sign substrate materials were exposed to the artificial accelerated weathering for 2000 hours. The ASTM D artificial accelerated weathering methodology is similar to the methodology used in AASHTO M The evaluation team loaded the artificial weathering device with as many samples as possible; see Figure 7 for an image of the samples prior to starting the accelerated weathering. The samples put into the accelerated weathering device were larger in size than required by the ASTM tests so that they could be machined to the appropriate size after the artificial accelerated weathering. This allowed the evaluation team to remove the edge portion of the material to achieve the proper size for testing. Removing the edge portion of the material reduced the uncertainty of the impact of the accelerated weathering on the cut edge of the material that would have otherwise been exposed. In addition to the samples for these ASTM tests, additional samples were included for other testing areas that will be described later. Figure 8 provides an image of the samples in the weathering device after the artificial weathering had concluded. Page 7

13 Figure 7. Samples prior to Starting the Accelerated Weathering. Figure 8. Samples after Accelerated Weathering. The flexural, tensile, and shear testing was conducted using the same ASTM standard test methods as described in Chapter 2. All testing was conducted in ambient lab conditions. Only the substrate materials were tested; no sign sheeting material was present on the substrates. Page 8

14 FLEXURAL TESTING Figure 9 shows the ES1 samples after testing. Table 5 provides the resulting data from the testing. The testing resulted in a flexural modulus value of approximately 345,000 psi. The flexural strength at break was approximately 6200 psi. Figure 9. Samples after Flexural Testing. Table 5. Flexural Testing Results. Substrate Material Sample 1 ASTM D Flexural Testing Flexural Strength at Break (psi) Sample 2 Sample 3 Sample 4 Sample 5 Average Flexural Strength at Break (psi) Average Flexural Modulus (10 3 psi) ES TENSILE TESTING Figure 10 shows the ES1 samples after testing. Table 6 provides the resulting data from the testing. The testing resulted in a tensile modulus value of approximately 388,000 psi. The tensile strength at break was approximately 3300 psi. Page 9

15 Figure 10. Samples after Tensile Testing. Table 6. Tensile Testing Results. Substrate Material Sample 1 Tensile Strength at Break (psi) Sample 2 Sample 3 Sample 4 ASTM D Tensile Testing Sample 5 Average Tensile Strength at Break (psi) Average Tensile Elongation at Break (%) Average Tensile Modulus Young's (10 3 psi) ES SHEAR STRENGTH TESTING Figure 11 shows the ES1 samples after testing. Table 7 provides the resulting data from the testing. The testing resulted in a shear strength value of approximately 5900 psi. Figure 11. Samples after Shear Testing. Page 10

16 Table 7. Shear Testing Results. ASTM D Shear Strength Testing Substrate Material Shear Strength (psi) Sample 1 Sample 2 Sample 3 Sample 4 Sample 5 Average Shear Strength (psi) ES BEFORE AND AFTER COMPARISON A summary of the flexural, tensile, and shear testing results before and after the sample substrate materials had been exposed to artificial accelerated weathering is provided in Table 8. Table 8. Before and After. Material Property Tested Before ES1 After Average Flexural Strength at Break (psi) Average Flexural Modulus (10 3 psi) Average Tensile Strength at Break (psi) Average Tensile Elongation at Break (%) Average Tensile Modulus Young's (10 3 psi) Average Shear Strength (psi) Page 11

17 CHAPTER 4: ADHESION TESTING This chapter describes the adhesion testing that evaluated the ability of sign sheeting material to adhere to the sample substrate materials. An aluminum sign substrate material was included in portions of the testing to serve as a comparison. The protocol in ASTM D , Standard Test Method for Pull-off Strength of Coatings Using Portable Adhesion Testers, was followed during the testing. A Proceq Z16 pull-off tester with digital display was used as the testing device; see Figure 12. Testing was conducted at ambient lab conditions on all sheeting types and at 40 F, 0 F, 100 F, and 145 F on two sheeting types. Figure 12. Pull-off Tester. An approximately 10 in by 10 in sample for each substrate and for each sheeting type was cut. Table 9 indicates the sign sheeting types used in the study. The evaluation team attempted to achieve a balance between manufacturers and sheeting types. The substrate was wiped clean prior to applying the sheeting with a hand squeeze roll applicator. The loading fixtures (20 mm diameter) were attached with an adhesive to the sign sheeting material. The sign sheeting material was lightly sanded and cleaned prior to mounting the load fixtures to aid in adhesion. Page 12

18 The area around the fixture was scored so that the surrounding material would not influence the recorded pull-off value. Three valid adhesion tests were conducted for each sample. Table 9. Sheeting Types to Evaluate. Sheeting Type Material Engineering/Super Engineering NC Engineering Grade Prismatic 3M 3430 High Intensity NC N500 High Intensity Prismatic 3M 3930, AD T-6500 Diamond/Omni/Crystal AD T-9500, NC ADHESION TESTING AT AMBIENT TEMPERATURES Table 10 provides the results of the adhesion testing at ambient temperatures. Seven sign sheeting types were applied to the substrate materials. The pull-off strength results indicate that there is a bigger influence on pull-off strength between the sign sheeting materials than between the substrate materials. The failure mode when the maximum pull-off value was reached was not always because the sheeting lost its bond with the substrate. Some samples resulted in the sheeting material delaminated from itself, as opposed to the entire sheeting material pulling away from the substrate. Some samples had a combination of substrate bond and internal sheeting material failure. Table 11 provides the results of the failure mode for the adhesion testing at ambient temperature. The values in the table represent the percent of the substrate exposed after the test. A value of 100 percent would indicate the sheeting material was completely removed from the substrate, representing a complete bond failure with the substrate. A value of 0 percent would indicate the sheeting material delaminated from itself because the internal sheeting material bonds were not as strong as the adhesive bond with the substrate material. Page 13

19 Table 10. Adhesion Testing Results at Ambient Temperature. ASTM D Pull-off Strength Testing All units in psi Sheeting Material Substrate Material Average (psi) Sample 1 Sample 2 Sample 3 NC SEG ES Aluminum M 3430 EGP ES Aluminum NC 500 HI ES Aluminum M 3930 HIP ES Aluminum AD T-6500 HIP ES Aluminum AD T-9500 OV ES Aluminum NC CG ES Aluminum Table 11. Adhesion Testing Failure Mode at Ambient Temperature. ASTM D Pull-off Strength Testing Sheeting Material Substrate Material Percent Substrate Exposed (%) Sample 1 Sample 2 Sample 3 NC SEG ES Aluminum M 3430 EGP ES Aluminum NC 500 HI ES Aluminum M 3930 HIP ES Aluminum AD T-6500 HIP ES Aluminum AD T-9500 OV ES Aluminum NC CG ES Aluminum Page 14

20 ADHESION TESTING AT VARIOUS TEMPERATURES All the tests at the various temperatures were conducted after conditioning the materials according to ASTM D This required keeping the material in a controlled environment at the desired temperature for at least 24 hours. The temperatures evaluated were 40 F, 0 F, 100 F, and 145 F. While conditioning the samples (substrate with sheeting and loading fixtures applied), the evaluation team evaluated the materials for any apparent outgassing. It was expected that outgassing, if present, would be more prevalent at the higher temperatures. The evaluation team did not see any apparent outgassing, which would have been indicated by bubbles in the sheeting material or loose sheeting material. The testing at the various temperatures followed the same procedure as at ambient temperatures. Only the 3M 3930 HIP and the AD T-9500 OV material were included as the sign sheeting types. The aluminum substrate was only evaluated at the extreme temperatures for comparison purposes. Due to the nature of the sample conditioning and testing the pull-off strength, two separate sets of data were collected. After the sheeting was applied to the substrate, six loading fixtures were applied to the sheeting and allowed to cure. The samples were then conditioned to the appropriate temperature. Immediately after the conditioning was complete, the samples were tested. Figure 13 provides an image of the adhesion testing at 40. Figure 13. Adhesion Test at 40. Three valid adhesion tests were conducted for each sample. After the samples had conditioned back to the ambient lab temperature, the remaining load fixtures were tested. Typically the initial testing would use more than three of the load fixtures. If this was the case, Page 15

21 additional fixtures were applied to the sheeting and then removed at ambient temperature. Table 12 provides the results of the adhesion testing at various temperatures. For comparisons purposes, the ambient data for the 3M 3930 HIP and AD T-9500 OV material have also been provided in the table. Table 11 provides the results of the failure mode for the adhesion testing at the various temperatures. Table 12. Adhesion Testing Results at Various Temperatures. ASTM D Pull-off Strength Testing Temp ( F) Sheeting Material 3M HIP Ambient Ambient AD T OV 3M 3930 HIP AD T OV 3M 3930 HIP AD T OV 3M 3930 HIP AD T OV 3M 3930 HIP AD T OV At Indicated Temperature (psi) After Recovery to Ambient (psi) Substrate Sample Sample Sample Average Sample Sample Sample Average Material ES Aluminum ES Aluminum ES ES ES Aluminum ES Aluminum ES ES ES Aluminum N/A ES Aluminum Page 16

22 Table 13. Adhesion Testing Failure Mode at Various Temperatures. ASTM D Pull-off Strength Testing Percent Substrate Exposed (%) Temp ( F) 40 Sheeting Material 3M 3930 HIP At Indicated Temperature After Recovery to Ambient Substrate Sample Sample Sample Sample Sample Sample Material ES Aluminum ES AD T-9500 OV Aluminum M 3930 HIP ES AD T-9500 OV ES Ambient 3M 3930 HIP ES Aluminum Ambient AD T-9500 OV ES Aluminum M 3930 HIP ES AD T-9500 OV ES M 3930 HIP ES Aluminum AD T-9500 OV ES Aluminum ADHESION TESTING AT AMBIENT TEMPERATURE AFTER ACCELERATED WEATHERING Due to size constraints of the accelerated weathering unit, a reduced number of samples and smaller sample sizes were included for testing. Two sign sheeting materials (3M 3930 HIP and AD T-9500 OV) and both substrate materials (ES1 and aluminum) were included in the test. The samples were 4 in by 6 in and had the sheeting applied prior to the start of the accelerated weathering. The sign sheeting faced the light source during the testing for both sheeting types. An additional sample for each substrate with the 3M 3930 HIP sheeting was placed facing away from the light source. The loading fixtures were attached after the accelerated weathering testing was complete. Due to the reduced sample size, only two adhesion tests were performed for each substrate and sheeting combination. The adhesion tests were conducted at ambient lab temperature. Page 17

23 Figure 14 shows the ES1 samples after the adhesion testing. Figure 15 shows the aluminum samples after the adhesion testing. Table 14 provides the results of the adhesion testing at ambient temperatures after the accelerated weathering. Comparing these values after the accelerated weathering to the ambient values with the weathering indicates these values are much higher in some cases. The prolonged heat and length of time the material had been applied to the substrate may have strengthened the bond to the substrate materials. Many of the failure modes when the maximum pull-off value was reached were because the sheeting material delaminated from itself, as compared to the entire sheeting material pulling away from the substrate. Figure 14. EcoStrate 1 Substrate Samples. Figure 15. Aluminum Substrate Samples. Page 18

24 Table 14. Adhesion Testing Results after Accelerated Weathering at Ambient Temperature. ASTM D Pull-off Strength Testing Sheeting Facing Toward Light Source (psi) Sheeting Facing Away From Light Source (psi) Sheeting Substrate Sample 1 Sample 2 Average Sample 1 Sample 2 Average Material Material 3M 3930 ES HIP Aluminum AD T- ES OV Aluminum Page 19

25 CHAPTER 5: FREE VIBRATION TESTING This chapter describes the free vibration testing that evaluated the ability of sign substrate material to absorb vibrations. This testing determined the damping ratio of the substrate materials. A fixed displacement of the free end of the substrate was used to generate the vibration. A 12 in by 18 in sample of the substrate material was tested at 40 F, 0 F, ambient lab temperature, 100 F, and 145 F. A further reduced size 4 in by 6 in sample was also tested at the ambient and extreme temperatures. This smaller size was needed to compare the results with the small samples that were placed in the accelerated weathering device. The weathered samples were only evaluated at ambient lab conditions. When testing at the various temperatures, the samples were conditioned to the desired temperature and immediately placed into the testing apparatus in the lab and tested as quickly as possible to minimize temperature changes. Only the substrate materials were tested; no sign sheeting material was present on the substrates. All tests were conducted after conditioning the materials according to ASTM D Aluminum substrate materials were also tested at the ambient temperature. Testing the various sizes allowed the evaluation team to see if the testing was scalable between the different sizes. The smaller sizes were needed to accommodate the conditioning of the materials at the desired temperatures and to accommodate the accelerated weathering. Two samples of the substrate were tested for each size and temperature combination. Each sample was tested twice. FREE VIBRATION TESTING SETUP AND CALCULATIONS To conduct the free vibration testing, the evaluation team restricted the sample at one end by clamping it to a lab work bench. The other end was subjected to the vibration. A fixed displacement of the free end of the substrate was used to generate the vibration. The vibration was monitored by a small accelerometer of insignificant weight placed at the end of the sample in the middle. The accelerometer was connected to an oscilloscope to monitor the vibration. The oscilloscope was connected to a laptop and software was used to document the data. Figure 16 provides an image of the free vibration test setup. Page 20

26 Figure 16. Free Vibration Test Setup. To determine the damping ratio (ξ), the evaluation team needed to determine the logarithmic decrement (δ), which represents the rate of decay of motion of a freely vibrating object. As the damping ratio increases, the rate of decay of motion also increases, which results in the substrate undergoing fewer cycles and more quickly absorbing high stress loadings. An ideal substrate material would have a high damping ratio and high ductility, while maintaining high flexural, tensile, and shear strength characteristics. The equations to determine the logarithmic decrement and damping ratio are provided below. The displacement at the i th peak is indicated by u i, the displacement at a later peak is represented by u i+j, and j represents the number of cycles that separate the peaks. δ = 1 j ln ( u i u i+j ) ξ δ 2π Page 21

27 FREE VIBRATION TESTING RESULTS Table 15 provides the average results of the free vibration testing at all temperatures. While the damping ratio plays a role in the signs ability to withstand vibrations, as generated by wind or passing vehicles, it is not the only factor that impacts durability in the field. The physical strength properties of the material such as flexural, tensile, and shear strength also play a role in the substrates durability. Table 15. Damping Coefficient Results at Various Temperatures. Substrate Temp ( F) Size (in) δ ξ ES ES ES ES Ambient Aluminum ES Ambient 4 6 Aluminum ES ES ES Weathered ES Samples Page 22

28 CHAPTER 6: PROJECTILE IMPACT TESTING This chapter describes the results of the projectile impact testing. Signs getting shot, especially in rural areas, are an ever present maintenance concern. Typically when an aluminum sign is shot, the bullet will pass through leaving a small hole where it entered and a slightly larger hole with sharp edges where it exits. The sign for the most part will still be functional after being shot. There is concern that a recycled plastic substrate material may behave differently than aluminum, especially at low temperatures. The concern is that the sign substrate may shatter; rendering the sign useless if it is shot. The temperatures evaluated for the impact testing were 40 F, 0 F, ambient, 100 F, and 145 F. All tests were conducted after conditioning the materials according to ASTM D Only the substrate material was tested, no sign sheeting material was present on the substrate. The evaluation team used common firearms for the testing including a 12 gauge shotgun (with #4 steel shot and #7.5 lead shot birdshot shells), a 9 mm pistol, a.22 caliber rim fire rifle, a.223 caliber center fire rifle, and a caliber center fire rifle. Varieties of sizes were tested to accommodate the various temperatures and accelerated weathering conditions. A full size 36 in by 36 in sized substrate was tested at ambient temperature. A 12 in by 18 in sample was tested at all temperatures. A 4 in by 6 in sample to be compared with the accelerated weathering samples was tested at 40 F, ambient temperature, and 145 F. The accelerated weathering samples were only tested at ambient temperature. The samples were conditioned to the desired temperature and immediately placed into the testing apparatus and tested as quickly as possible to minimize temperature changes. All firearms were used for the 36 in by 36 in and 12 in by 18 in testing. Only the 9 mm pistol was used for the 4 in by 6 in testing. Two shots from each firearm were fired at each substrate. IMPACT TESTING SETUP The impact testing required the evaluation team to take the testing outside to an area where firearms could safely be discharged. The range area included a wood berm to absorb the bullets after they had passed through the substrate materials. The firearm operators wore hearing Page 23

29 protection and safety glasses while conducting the testing. All firearm safety rules were followed during all tests. The sign substrates were mounted in two ways. Figure 17 shows the first mounting technique on a typical sign pole using sign mounting brackets. This setup allowed the evaluation team to determine if there was any damage around the mounting holes and if the damage to the sign was similar to the other mounting technique. Select testing of the 36 in by 36 in, 12 in by 18 in, and 4 in by 6 in samples occurred while mounted on the pole. Figure 18 shows the second mounting technique. The second mounting technique was developed to allow the evaluation team to quickly setup the 12 in by 18 in and 4 in by 6 in samples for the testing at various temperatures. The signs temperature would change from the conditioned temperature if time was taken to mount it to the pole. To help combat the changing temperatures from where the materials were conditioned to where they were tested, the evaluation team used a Styrofoam cooler to maintain the samples near the desired temperature; see Figure 19. The box was rigged with a variable heat source to maintain the higher temperatures or with varying amounts of dry ice to maintain the lower temperatures. A temperature sensor with a remote probe was used to monitor the temperature inside the box. Figure Sign Mounted to Pole prior to Impact Testing. Page 24

30 Figure 18. Impact Testing Setup. Figure 19. Holding Box with Temperature Sensor for Conditioned Materials. Page 25

31 Initial testing was conducted to determine if there were any notable differences in results between signs mounted in a typical fashion on a pole and signs mounted in the customized test jig that allows the signs to be mounted and changed quicker. The initial testing did not produce any notable differences in the damage to the substrate around the bullet hole area. The bullet hole sizes were similar for both mounting types. There appeared to be some minor damage around the mounting holes for the signs mounted to the pole. The resulting damage from the bullets was evaluated by measuring the diameter (in inches) of the damaged area. The front (bullet entry) and back (bullet exit) were both evaluated. IMPACT TESTING AT AMBIENT TEMPERATURE Table 16 provides the results of the impact testing at ambient temperature. As anticipated, the exit hole is typically larger than the entry hole. The diameter of the shotgun damage was influenced by the shooting distance, which was not always consistent. The cells in the table with a dash were combinations not evaluated. Figure 20 provides an image of the back side of the ES1 substrate that had been shot with the 9 mm and.22 caliber firearms at ambient temperature. The 9 mm bullet holes are the top two holes, and the.22 caliber holes are the bottom two holes. The diameter of the damaged area is written on the substrate near the holes. The damage for all of the ambient tests was limited to the area directly around the bullet with the exception of the tests when mounted on the pole. There was some minor damage to the substrate around the mounting hole (described later). Table 16. Impact Testing Results at Ambient Temperature. Substrate Size (in) Sign Face Mount Type Shotgun (Steel) Shotgun (Lead) Firearm Used, 2 Shots Each, Damage in Inches 22cal cal - 2 9mm - 1 9mm ES Front Pole ES Back Pole ES Front Rack ES Back Rack ES Front Pole ES Back Pole ES1 4 6 Front Rack ES1 4 6 Back Rack Page 26

32 Figure 20. EcoStrate 1 Back of Substrate Ambient temp (9mm on Top,.22 cal on Bottom). IMPACT TESTING AT 100 F Table 17 provides the results of the impact testing at 100 F. Table 17. Impact Testing Results at 100 F. Substrate Size Firearm Used, 2 Shots Each, Damage in Inches Sign Mount Shotgun Shotgun 22cal 22cal 9mm 9mm (in) Face Type (Steel) (Lead) ES Front Rack ES Back Rack IMPACT TESTING AT 145 F Table 18 provides the results of the impact testing at 145 F. The cells in the table with a dash were combinations not evaluated. Page 27

33 Table 18. Impact Testing Results at 145 F. Substrate Firearm Used, 2 Shots Each, Damage in Inches Size Sign Mount Shotgun Shotgun 22cal 22cal 9mm 9mm (in) Face Type (Steel) (Lead) ES Front Rack ES Back Rack ES1 4 6 Front Rack ES1 4 6 Back Rack IMPACT TESTING AT 0 F Table 19 provides the results of the impact testing at 0 F. Table 19. Impact Testing Results at 0 F. Substrate Size Firearm Used, 2 Shots Each, Damage in Inches Sign Mount Shotgun Shotgun 22cal 22cal 9mm 9mm (in) Face Type (Steel) (Lead) ES Front Rack ES Back Rack IMPACT TESTING AT 40 F Table 20 provides the results of the impact testing at 40 F. The cells in the table with a dash were combinations not evaluated. Table 20. Impact Testing Results at 40 F. Firearm Used, 2 Shots Each, Damage in Inches Size Sign Mount Substrate (in) Face Type Shotgun (Steel) Shotgun (Lead) 22cal cal - 2 9mm - 1 9mm ES Front Rack ES Back Rack ES Front Pole ES Back Pole ES1 4 6 Front Rack ES1 4 6 Back Rack ES1 4 6 Front Pole ES1 4 6 Back Pole Figure 21 provides an image of the back side of the ES1 substrate that had been shot with the 9 mm and.22 caliber firearms at 40 F. The 9 mm bullet holes are the two bottom holes and the.22 caliber holes are the top two holes. The diameter of the damaged area is written on the Page 28

34 substrate near the holes. Figure 22 provides a comparison of the backside of a 12 in by 18 in sample that was mounted to a pole. In the image the holes are the mounting holes, not holes caused by a bullet. The original hole is on the right side of the image. The top two pictures on the left are the mounting holes after being shot at an ambient temperature. The bottom two pictures on the left are the mounting holes after being shot at 40 F. Only the backside of the substrate showed damage at the mounting holes. Figure 21. EcoStrate 1 Back of Substrate at 40 F (.22 cal on Top, 9 mm on Bottom). Page 29

35 Figure 22. EcoStrate 1, Sample on Pole Comparison. IMPACT TESTING AT AMBIENT TEMPERATURE AFTER ACCELERATED WEATHERING Table 21 provides the results of the impact testing at ambient temperatures after the accelerated weathering. Table 21. Impact Testing Results after Accelerated Weathering. Substrate Size Sign Mount Damage in Inches (in) Face Type 9mm - 1 9mm - 2 ES1 4 6 Front Rack ES1 4 6 Back Rack ES1 4 6 Front Rack ES1 4 6 Back Rack Page 30

36 CHAPTER 7: FINDINGS This chapter summarizes the findings from the evaluation and provides recommendations on testing that could be included in quality assurance testing plans. DISCUSSION OF FINDINGS Based on the testing conducted, the following areas concerning the EcoStrate sign substrate material were addressed: 1) what is the strength (flexural, tensile, shear), 2) how well will sign sheeting material adhere, 3) how well will the material withstand wind forces, 4) how well will the material withstand being shot with a gun, 5) how will accelerated weathering impact the material, and 6) how will a range of temperatures impact the performance of the material. The adhesion of sign sheeting materials to the EcoStrate substrate had similar performance to aluminum across the range of temperatures tested. The only temperature tested where the adhesion on the EcoStrate material was not as strong as aluminum was when the evaluation was conducted at 145 F. The testing did not look at cycling temperatures or how the adhesion is affected over time. Free vibration testing was conducted to determine the damping ratio of the substrate. The EcoStrate substrate displayed damping properties that were better than the aluminum substrate. The damping ratio was not affected by varying temperatures. The ability of the EcoStrate substrate to withstand projectile impacts from firearms was tested for a range of temperatures and firearms. The EcoStrate material did show some damage around the mounting holes when it was shot while mounted to a sign pole. During the testing, no total failures were encountered even at the lowest tested temperatures. Accelerated weathering did not negatively impact the performance of the EcoStrate substrate material for any of the areas evaluated. The most notable impact of the accelerated weathering was a visible discoloration of the substrate material that was facing the xenon arc lamp. During the temperature conditioning, there was no apparent outgassing under the sign sheeting material. It should be noted that the sign sheeting material was applied to the substrate at least three weeks after the substrate was manufactured. Page 31

37 RECOMMENDED TESTING Verifying the consistency of recycled composite substrate materials would need to be part of quality assurance testing plans if asset owners were to begin using these substrates. Based on the testing conducted, the evaluation team recommends at a minimum that tensile or flexural properties are evaluated according to the appropriate ASTM standard. This testing would only need to be conducted at ambient lab conditions. This testing would need to occur regularly due to the variable nature of recycled composite materials. Visual observations of the substrate materials and verification that the thickness of the material meets the requirements are simple ways to determine if additional testing may be required to verify consistency. The evaluation team recommends field testing the product as the ability of the lab testing to provide guaranteed field performance levels is limited without any specifications for required strengths and without any test methods that can accurately simulate the forces applied on signs during windy conditions. Page 32

38 REFERENCES 1. Roschke, P., B. Harrison IV, F. Benson. Recycled Content Sign Blanks. FHWA/TX-97/1338-1F. Texas Transportation Institute, The Texas A&M University System. October Zhang, HC. Image Microsystems Sign Substrate Material Test Report. Advanced Manufacturing Laboratory, Texas Tech University, Industrial Engineering Department. January Page 33