Performance of Corrugated Pipe Manufactured with Recycled Polyethylene Content (2011) / Chapter Skim
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From page 15... ...
One can also correct for the carbon black from the MDPE sample because each 1 Yield Stress Density= ( ) −81 250 73 500, , C H A P T E R 3 Findings
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0.970 0.942 0.952 Calculated Density 1 (g/cm 3 ) 0.943 0.937 0.925 Melt Index (g/10 min)
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These resins were made into plaques and characterized by a variety of tests. The full test reports for these materials are found in Appendix B, Section B.5.
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, Nylon, PET or polyvinyl chloride 18 Property TRI Repro 1 Average Range Density (g/cm3) 0.960 0.955 ± 0.005 0.946–0.960 Melt Index (g/10 min)
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From page 19... ...
The foreign particulate matter can be removed during the washing step at the recycler and filtered out during extrusion by either the recycler or pipe manufacturer. However, the recyclerswhoproducereprocessed HDPE are more capable of this because some of them already melt filter to 100–120 mesh while the pipe manufacturers generally filter at a mesh size of 80 or below.
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From page 20... ...
Five replicates were tested for the 100% MCRG and 10 were tested for the 50/50 MCRG/MDPE. Both sets of results indicate that melt filtration dramatically improves the properties of recycled HDPE and blends containing HDPE.
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mesh size. The results for both sets of results are shown in Figures 19 and 20.
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050 100 150 200 250 300 350 400 0 20 40 60 80 100 120 140 160 Filter Mesh Size Fa ilu re T im e (H rs) 0 20 40 60 80 100 120 0 20 40 60 80 100 120 140 160 Filter Mesh Size BA M F ai lu re T im e (hr s)
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23 CM–1 %T Figure 22. BAM test fracture surfaces for failure times of 12 h (left)
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From page 24... ...
It is clear though, that the stress-crack resistance begins to be compromised around 5% PP. Phase 2 -- Recycled-Resin Blends The results from Phase I of the project showed that recycled HDPE had properties that were below the established limits of AASHTO-approved pipe.
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From page 25... ...
y = 0.0089x + 0.2695 R2 = 0.9804 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0 2 4 6 8 10 12 % Polypropylene M el t I nd ex (g /10 m in) y = -23.388x + 628.65 R2 = 0.8882 0 100 200 300 400 500 600 700 800 0 2 4 6 8 10 12 % Polypropylene B re ak S tra in (% )
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From page 26... ...
what those limits were and to also enhance the properties of recycled HDPE by blending it with nonpipe virgin resins such as LLDPE and LMDPE. A secondary but important objective was to determine the relationships between the percentage component in a blend and the resulting blend's properties.
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From page 27... ...
MCRG + MDPE @ 25, 50, and 75%, MCR1 + MDPE @ 25, 50, and 75%, MCRG + PIR-MD @ 25, 50, and 75%, 75% MCR1 + 25% PIR-HD, and 50% VR3 + 25% MDPE + 25% MCR1. The effects of recycled content on the yield strength for four blends of virgin pipe resins with mixed-colored PCR are shown in Figure 28.
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From page 28... ...
The results of the blending and testing with mixed-color PCR HDPE have produced the following findings: 1. The maximum amount of mixed-color PCR that can be blended with one of the pipe resins and meet 24 hours of stress-crack resistance is about 20%.
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From page 29... ...
65% NAT + 35% PIR-LD, and 50% VR3 + 25% MDPE + 25% NAT. The effect of recycled content on the yield strength for four blends of virgin pipe resins with natural PCR is shown in Figure 31.
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From page 30... ...
However, the yield will be over 4,000 psi, so the NCLS test will be less severe for this blend. That means that the limit might be closer to 15%.
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It was determined that for simple, two component blends, the maximum amount of PCR-HDPE is around 15%, while a specific PIR-HD obtained could be used in amounts up to 40%. More importantly, it was found that through the relationships discovered during this task, other two and three component blends could be designed and optimized for the specific purpose of maximizing the amount of recycled HDPE used.
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From page 32... ...
It would be valuable to see the effects of adding these resins to recycled content. Phase 3 -- Pipe Made from Recycled-Resin Blends Trial Pipe Manufacturing A total of 15 trial pipe samples were prepared at three different manufacturing plants, designated Plants A, B
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From page 33... ...
0.952 0.951 0.952 0.950 0.948 0.952 0.949 0.945 0.948 0.945 0.949 0.951 0.955 0.955 0.953 Melt Index (g/10 min) 0.12 0.15 0.16 0.19 0.21 0.13 0.22 0.27 0.36 0.34 0.20 0.33 0.36 0.12 0.17 % Carbon Black 1.6 1.4 2.2 0.5 1.5 2.0 2.0 1.9 1.4 1.9 2.1 1.5 1.5 2.5 2.6 % Ash 0.1 0.3 0.2 0.4 0.2 0.0 0.4 0.3 0.1 0.4 0.7 0.4 0.0 0.0 0.3 % PP 0.0 0.7 0.2 1.4 0.3 0.0 1.9 1.7 1.0 2.2 2.5 2.4 0.0 0.0 1.8 Yield Stress (psi)
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From page 34... ...
2. The percentages of carbon black were below 2.0% in nine of 15 samples, which might suggest a lack of control by the corrugated pipe manufacturers.
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From page 35... ...
It is complimentary to the FL-DOT junction test because it can be performed on the same equipment and is run under the same conditions. The FL-DOT protocol calls for the evaluation of the junction between the corrugation and the liner with a stress-crack test on a 0.25-in.
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From page 36... ...
The three samples that only contained natural recycled HDPE had COVs of 14%, 4%, and 21%. These results suggest that the highest variability is in the MCR recycled content.
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There were six samples that did not meet the density requirement when the measured density was corrected for carbon black. This is an issue with the contaminants interfering with the accuracy of the test.
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From page 38... ...
Sample Formulation Failure Time (h)
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39 Sample Density1 MFI Flexural Modulus Yield Stress % Carbon Black NCLS OITemp M294 4 3 5 4 2–5% >18 hrs >220°C A1 4 4 5 5 1.6 28 257 A2 3 3 5 5 1.4 21 256 A3 5 3 5 5 2.2 <18 257 A4 4 3 5 5 0.5 18 256 A5 4 3 5 5 1.5 29 260 B1 4 4 5 5 2.0 26 253 B2 4 3 5 5 2.0 18 253 B3 3 3 5 4 2.0 30 256 B4 4 3 5 5 1.4 19 257 B5 3 3 5 4 1.9 19 256 L1 4 3 5 5 2.1 <18 240 L2 4 3 5 5 1.5 28 256 L3 4 4 5 6 1.5 39 256 L4 3 3 5 6 2.5 29 254 L5 3 5 5 2.6 26 256 1Measured density corrected for percentage carbon black. Note: MFI = melt flow index.
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From page 40... ...
temperature steps. The test was continued until the specimen yielded.
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From page 41... ...
These results will be used to evaluate how one would design with recycled formulations in the context of Section 12 of the AASHTO LRFD Bridge Design Specifications (15)
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From page 42... ...
Note: " -- " = data not available. Property Result Corrected Density 0.948 g/cm 3 Melt Index 0.11 g/10 min % Color 3.9 % Ash 0.7 % PP 4.8 Flexural Modulus 128,606 psi Yield Stress 3,260 psi Break Strain 21% NCLS Stress-crack Resistance 220 ± 54 hrs Table 18.
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From page 43... ...
were generated on tensile dumbbell specimens with very simple geometry. A pipe is likely to behave differently.
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From page 44... ...
Sample A5 contained 30% PCR-NAT, which is basically ground up milk and water jugs. The service-lifetime estimates are similar to 100% virgin.
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From page 45... ...
Additionally, these tests are typically run for 300 or 400 h. A durability test like this one is critical for the successful use of recycled HDPE in corrugated drainage pipe for highway applications.
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From page 46... ...
Designing Pipe with Recycled Content An evaluation of the existing design methodology outlined in Section 12 of the AASHTO LRFD Bridge Design Specifications was performed to determine its applicability to pipe manufactured with blends of virgin and recycled HDPE. In particular, the material properties needed to meet M294 required for the AASHTO LRFD design methodology were assessed.
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From page 47... ...
Scope 1.1 This specification covers the quality of HDPE-resin formulations containing recycled HDPE that are intended for use in AASHTO M252 -- Recycled approved corrugated drainage pipe for subsurface drainage applications, in sizes 75- to 250-mm diameter (3 to 10 in.)
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From page 48... ...
Appendix I -- Proposed Draft Standard Specification for Corrugated Polyethylene Drainage Pipe Containing Recycled Polyethylene, 300- to 1,500-mm Diameter 1. Scope 1.1 This specification covers the requirements and methods of tests for corrugated PE pipe, couplings, and fittings for use in surface and subsurface drainage applications.
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