Field Performance of Corrugated Pipe Manufactured with Recycled Polyethylene Content (2018)

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A-1 Draft Standard Test Method and ASTM Work Item for UCLS Test Date: December 4, 2015 To: ASTM F17 Main and ASTM F17.40 Subcommittee From: Michael Pluimer (Phone: 612-236-8169; Email: michael.pluimer@gmail.com) Re: WK48721 – New Standard Test Method for The Un-notched, Constant Ligament Stress Crack Test (UCLS) for HDPE Materials Containing Post-Consumer Recycled HDPE (PCR-HDPE) The attached draft new standard test method was developed as a method to determine the stress crack resistance of HDPE materials containing post-consumer recycled polyethylene content. It was developed primarily for corrugated HDPE pipe manufactured with recycled materials. Unlike other existing stress crack methods such as the NCLS (ASTM F2136) and NCTL (ASTM D5397), this test method involves the use of un-notched test specimens and relies on the pres- ence of a contaminant to act as a stress riser for the origination of the crack. This test method was originally developed by Richard Thomas (TRI/Environmental, Austin, TX) and referred to as the “BFF test” in NCHRP Report 696, Performance of Corrugated Pipe Manufactured with Recycled Polyethelene Content. This test method was balloted to Subcommittee F17.40 in September 2015. It received 5 nega- tives. A task group meeting was held during ASTM F17 Committee Week in Tampa, and all of the negatives were addressed. Your support of this new proposed test method is greatly appreciated. Best regards, Michael Pluimer President/Owner Crossroads Engineering Services, LLC michael.pluimer@gmail.com; Ph: 612-236-8169 A P P E N D I X A

A-2 Designation: WK 48721 – DRAFT 2.0 Date: December 4, 2015 To: ASTM F17.40 and ASTM F17 Main Committees Tech. Contact: Michael Pluimer Work Item: WK48721 Ballot Action: New Standard Test Method Rationale: This new standard test method is proposed to evaluate the effects of con- taminants with regards to stress cracking for HDPE materials containing post-consumer recycled content Standard Test Method for The Un-notched, Constant Ligament Stress Crack Test (UCLS) for HDPE Materials Containing Post-Consumer Recycled HDPE This standard is issued under the fixed designation F XXXX; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (ε) indicates an editorial change since the last revision or reapproval. 1. Scope 1.1 This test method covers an un-notched constant ligament stress (UCLS) test for use with HDPE materials that contain post-consumer recycled HDPE (PCR-HDPE). Contami- nants in the PCR-HDPE can initiate stress cracks at elevated temperatures, and this test method evaluates the response of these materials to a constant applied stress. 1.2 The test method is focused on HDPE corrugated pipe containing PCR-HDPE, but can be used in other applications where PCR-HDPE is used. 1.3 The test utilizes the same devices used to perform the NCTL test (ASTM D5397) and the NCLS test (ASTM F2136), but the test is conducted with different specimens and with the use of water instead of a surfactant solution. The test specimen is larger than standard NCLS and NCTL specimens to increase the number of contaminant particles in the specimen that might grow cracks. 1.4 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard. 1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. 2. Referenced Documents 2.1 ASTM Standards: D1600 Standard Terminology for Abbreviated Terms Relating to Plastics D2837 Standard Test Method for Obtaining Hydrostatic Design Basis for Thermo- plastic Pipe Materials or Pressure Basis for Thermoplastic Pipe Products D4703 Practice for Compression Molding Thermoplastic Materials into Test Speci- mens, Plaques, or Sheets D5397 Test Method for Evaluation of the Stress Crack Resistance of Polyolefin Geo- membranes Using Notched Constant Tensile Load Test (NCTL) D5947 Standard Test Methods for Physical Dimensions of Solid Plastic Specimens D638 Standard Test Method for Tensile Properties of Plastics F412 Standard Terminology Relating to Plastic Piping Systems F2136 Test Method for Notched, Constant Ligament-Stress (NCLS) Test to Determine Slow-Crack-Growth Resistance of HDPE Resins or HDPE Corrugated Pipe

A-3 2.2 AASHTO Documents: National Cooperative Highway Research Program (NCHRP) Report 696 3. Terminology 3.1 Definitions: Definitions are in accordance with Terminology F412, and abbreviations are in accordance with Terminology D1600, unless otherwise specified. 3.2 Definitions of Terms Specific to this Standard: 3.2.1 Bi-directional shift constants, n – Constants used to shift elevated temperature and stress data to service conditions; e.g., Popelar shift constants for HDPE. 3.2.2 Contaminant, n – inorganic particulate matter or other non-HDPE material that creates inclusions or stress risers in the crystalline structure of HDPE. 3.2.3 Post-consumer recycled HDPE (PCR-HDPE), n – HDPE materials from products that have served a previous consumer purpose (e.g., laundry detergent bottles, milk bottles and other consumer goods). 4. Significance and Use 4.1 This test method is a way to evaluate the effects of contaminant particles found in HDPE products containing PCR-HDPE, primarily corrugated pipe. Particles of significant num- ber, size and shape can reduce the slow crack growth resistance of the products. This test is performed in water without a controlled defect such as a notch. Since there is no notch, it is not necessary to use a surfactant in the water bath. It is a constant load test. 4.2 This test may be used to evaluate various blends of recycled and virgin materials. For example, a material with high stress crack resistance and few contaminants can be blended with materials that are less resistant to cracking to enhance the overall stress crack resis- tance of the blend. 4.3 The test can be conducted at various temperature and stress conditions. If at least 3 differ- ent temperature/stress conditions are evaluated, an estimate of the service lifetime of the material can be predicted with the use of bi-directional shifting or the rate process method. 4.4 The test can also be performed under a single applied load and a single temperature to create a single point test useful for comparative purposes as well as for quality control. 5. Apparatus 5.1 Blanking Die—A die suitable of cutting ASTM D638, Type I tensile specimens. Alterna- tively, specimens may be prepared by machining. 5.2 Stress-Crack Testing Device—A lever-loading machine with a mechanical advantage of up to 10:1. The most common devices used for corrugated pipe resins have a maximum mechanical advantage of 5:1, but higher ratios would allow for testing of thicker speci- mens. The device is similar or identical to those used for Test Methods D5397 and F2136. The device shall have a timer capable of recording failures within the nearest 0.1 hr. for each individual lever arm. The timer must stop when a test specimen fails. An example of an acceptable device is shown in Figure 1. 5.3 Water Bath—A heated and stirred water bath deep enough to cover the test specimens mounted in the frame to a point above the reduced section and into the top tab. The bath must be capable of heating to a constant temperature of 80 ± 1 °C. Note 1 – Baths that once contained surfactant solutions for other stress crack tests are extremely difficult to clean. Residual surfactant will reduce the failure times of this test and may stay present for many months and after many cleanings. 5.4 Compression Molding Press and Mold—A set-up for compression molding a plaque at least 7 in. (178 mm) by 7 in. (178 mm) and cooling it at 15°C per minute in accordance with Practice D4703. The mold shall be designed in a way to allow the removal of at least five D638, Type I tensile specimens with the geometry described in Section 6. 6. Test Specimen 6.1 Plaque—A compression molded plaque manufactured in accordance with Practice D4703 with a cooling rate of 15°C per minute. A flash picture-frame mold or a flash mold with machined cavity can be used. The mold must be capable of producing a plaque that

A-4 is 0.04 ± 0.005 in. (1.0 ± 0.1 mm) thick for a width of 2.25 in. (57.1 mm), then transitions to a thickness between 0.09 in. (2.3 mm) and 0.095 in. (2.4 mm). The transition must occur across 1.125 in. (28.6 mm) on either side of the narrow section and stay constant for the full length of the test specimen [6.5 in. (170 mm)]. This will result in a narrow area for the test specimen that is 0.50 in. (12.7 mm) wide and 2.25 in. long (57.1 mm) and 0.04 ± 0.005 in. (1.0 ± 0.1 mm) thick. The end tabs must be between 0.090 and 0.095 in. (2.3 and 2.4 mm) thick. The thickness will transition from the narrow section to the ends across 1.125 in. (28.6 mm) on either side. Note 2: It is important that the material is adequately homogenized prior to compres- sion molding into a plaque. This may be done via melt blending with a twin screw lab extruder or other methods that are deemed effective at homogenizing blends of plastic materials. 6.2 Test Specimen—The test specimen produced from the plaque described in Section 6.1. The specimen is prepared by cutting out a D638 Type I specimen from a compression molded plaque prepared according to 5.4. Next, a hole, 0.219 in. (5.6 mm) is placed in each tab with the use of a 7/32 in. drill bit. The finished specimen and associated dimensions are shown in Figure 2 and Table 1. At least 5 specimens are recommended for each material tested. Figure 1. UCLS test apparatus. Figure 2. UCLS test specimen (dimensions in Table 1).

A-5 7. Procedure 7.1 Measure the width and thickness of each test specimen to an accuracy of 0.001 in. (0.03 mm) in accordance to ASTM D5947. Calculate the load necessary to apply a tensile stress of 650 psi (4.48 MPa) onto the test specimen with the following equation: AL t w lw gw MA[ ]( )( )( )= σ − + where: AL = applied load (lb) s = applied stress (psi) t = thickness (in.) w = width (in.) lw = lever weight (lb) gw = grip weight (lb) MA = mechanical advantage 7.2 Attach five test specimens to the load frame and place the frame into the water bath that has been pre-heated and stabilized at the test temperature. 7.3 Prepare each weight tube to the weight necessary to apply the proper stress to each indi- vidual lever arm. Include the attachment pin as part of the applied load. Apply the weight tubes to the lever arms, taking care to apply the load gently. Reset the timers to zero to start the test. 7.4 Once the test has been terminated, record all the failure times and make note of whether the failure occurred in the reduced area or near the grip. Specimens that fail near the grip shall be classified as a non-test and shall not be considered in any data analysis. Also note whether the crack started at an edge (one ductile “horn”) or in the center of the specimen (2 ductile “horns”). See Figure 3 for examples of typical failures that occur in this test. 8. Single Stress and Single Temperature Test for Quality Assurance 8.1 The standard conditions for quality control or quality assurance testing are a tempera- ture of 80.0 ± 1.0 °C and an applied initial stress of 650 psi (4.48 MPa). 8.2 The minimum required failure time at these standard conditions shall be specified in the respective product standards. 9. Multiple Conditions for Service Lifetime Estimates 9.1 Test five specimens each under the following set of conditions: I) 80°C and 650 psi of stress II) 80°C and 450 psi of stress III) 70°C and 650 psi of stress Description (see Figure 1) Dimension in. (mm) Description (see Figure 1) Dimension in. (mm) LO – Overall length ≥ 6.50 (170) w – Width of narrow section 0.50 ± 0.02 (13 ± 0.5) L – Length of narrow section 2.25 ± 0.02 (57 ± 0.5) TO – Maximum thickness of specimen ≥ 0.90 (23) D – Distance between taper 3.96 ± 0.04 (100 ± 1) t – Thickness of test section 0.040 ± 0.005 (1 ± 0.1) R – Radius of fillet 3.00 ± 0.04 (76.2 ± 1) HC – Distance to hole center 0.375 ± 0.020 (9.5 ± 0.5) G – Gage length 2.00 ± 0.01 (50.8 ± 0.3) DH – Hole diameter 0.219 ± 0.020 (5.6 ± 0.5) WO – Overall width 0.75 ± 0.25 (19 ± 6) Table 1. Dimensions for test specimen shown in Figure 2.

A-6 Once each set of five specimens has broken, record the failure times and note whether the failure occurred in the reduced section or near the grips. Failures that occur near the grips shall not be considered in the analysis. The service lifetime of the material at ambient tem- peratures and field stress can be predicted by using bi-directional shifting to create a master curve at the desired ambient temperature or by using the Rate Process Method as detailed in the Appendices in ASTM D2837. 10. Report 10.1 Report the following general information: 10.1.1 Complete identification of the material. 10.1.2 Details of the plaque preparation, including cooling rate. 10.1.3 The test temperature. 10.1.4 The applied initial room temperature stress. 10.1.5 The length, width, and thickness of the reduced area section of the test specimen. 10.1.6 The calculations for applied stress, including any adjustment for the weight of the loading levers. 10.2 Report the following for a single point test: 10.2.1 The failure times for the 5 specimens, the average failure time and the standard deviation. 10.3 Report the following for a service lifetime estimate: 10.3.1 The three sets of conditions (temperature and stress) 10.3.2 The 15 failure times, the averages and standard deviations for each set. 10.3.3 The multiplication factor used for shifting and the temperature to which the data were shifted. 10.3.4 A plot of log shifted stress vs. log shifted time. 10.3.5 The estimated failure time under the typical conditions (factored service stress and temperature) and the estimated stress for 50 and 100 year estimated ser- vice lifetimes. 11. Precision and Bias Since failure times of test specimens are dependent on the presence of contaminants, there is naturally significant scatter in the test results. Data to determine the precision and bias of this test method is currently being generated and will be incorporated into this stan- dard upon completion. Figure 3. Typical UCLS failure caused by contaminant in the specimen.

A-7 12. Keywords Post-consumer recycled HDPE; NCLS; UCLS; Contaminant; Corrugated HDPE pipe; BFF; Recycled plastics; Recycled materials; Corrugated plastic pipe APPENDIX (Non-mandatory information) X.1 Procedure for estimating service life of material using bi-directional shift factors