Retrospective Evaluation of Cured-in-Place Pipe - (NEPIS)(EPA ...

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6.4.5 Strength and Flexural Modulus. The flexural strength and flexural modulus are the most often tested structural parameters for a CIPP lining, not least because minimum values are given for only these two structural parameters in the ASTM F1216 standard. A compilation and comparison of the available data from this study on these flexural test parameters and tensile test parameters is provided in Table 6-4. For flexural strength, no values measured fall below the ASTM minimum of 4,500 psi. The measured values range from 5,032 psi to 7,264 psi with quite small standard deviations for each set of measured values. Excluding one of the 2010 Denver 48-in. sample set values of 5,032 psi, the remaining tensile strength values fall into quite a narrow range of 5,808 psi to 7,264 psi. Table 6-4. Comparison of Strength, Modulus and Elongation Values for All Liner Samples Flexural Flexural Tensile Tensile Tensile Tensile Strength Modulus Strength Modulus Elongation at Elongation at Liner Age Location (psi) (psi) (psi) (psi) Peak Stress (%) Break (%) a ASTM F1216 min. value 0 N/A 4,500 250,000 N/A N/A N/A N/A Crown 6,454 ±228 329,768 ±18,429 3,047 ±235 411,789 ±64,990 1.2 – 2.5 2.0-4.5 Denver 8-in. 25 Spring line 6,712 ±571 340,044 ±18,381 2,990 ±205 401,069 ±262 1.45-1.65 1.5-3.5 Invert 7,103 ±702 336,209 ±23,759 3,051 ±167 422,006 ±44,988 2.25-2.4 1.5-4.5 Denver 48-in. DS 23 Crown 7,031 ±346 302,960 ±24,303 2,995 ±227 382,420 ±60,141 1.5-2.5 2.5-9.0 Denver 48-in. US (Set 1) Denver 48-in. 23 Crown 5,032 ±652 6,117 182,622 ±23,126 263,707 3,208 ±222 426,787 ±58,396 1.9-2.5 1.5-5.5 US (Set 2) ±888 ±70,398 Denver 48-in. (Insituform) 8 Crown 6,900 ±400 490,000 ±40,000 2,300 ±170 N/A N/A 1.5-2.0 Crown 7,199 ±2190 366,563 ±42,340 4,020 ±340 404,641 ±49,467 1.5 – 2.5 1.0-11.0 Columbus 8-in. 5 Spring line 6,422 ±2351 328,118 ±57,614 3,696 ±560 338,849 ±15,656 1.75-2.4 2.5-9.0 Invert 5,627 ±1635 343,470 ±51,125 3,882 ±374 344,275 ±25,215 1.0-1.5 5.0-8.0 Columbus 8-in. (QA) 0 N/A 7,264 ± 500 464,652 ±30,000 N/A N/A N/A N/A Columbus 36-in. 21 Upper haunch 6,039 ±396 206,805 ±29,065 2,958 ±251 315,259 ±42,504 1.0-1.2 2.5-6.0 Note: (a) Tensile elongation at break is not a standardized test; no claims are made herein regarding the repeatability of these measurements or their exact engineering meaning. It is a performance indicator which is believed by some to be linked to the uniformity of the resin saturation within the felt. For flexural modulus, only two average values fall below the minimum of 250,000 psi given in the ASTM F1216 standard. These are for the 2010 Denver 48-in. upstream liner sample with an average flexural modulus of 182,622±23,126 (Set 1) and for the Columbus 36-in. liner sample with an average flexural modulus of 206,805±29,065. Retesting with five new coupons cut from the Denver 48-in. upstream liner sample (Set 2) gave higher results that exceeded the ASTM minimum modulus value. 98
Looking for correlations to the low modulus value, it can be noted that the flexural strength recorded for Set 1 of the Denver 48-in. upstream liner was also the lowest value measured. However, the tensile test data (representing different coupons from the same sample) were at the upper end of the range of the remaining results. For the Columbus 36-in. liner with the low flexural modulus value (which was installed as an emergency change order to an existing contract), the flexural strength and tensile strength were all near the bottom of the range for all the liner samples, but were not the lowest values. However, the tensile modulus for the Columbus 36-in. liner was the lowest value recorded. The 1995 sample of the Denver 48-in. liner was measured with an average flexural modulus of 490,000 psi, which was the highest value recorded in the data included in this study. The remaining modulus values measured in this study (excluding the Denver 48-in. upstream liner and the Columbus 36-in. liner) range from 263,707 psi to 366,563 psi. An additional flexural modulus value of 464,652 psi was a recorded value from the QA/QC testing during installation of the Columbus 8-in. liner. Hence, the two flexural modulus values measured by other laboratories (464,652 and 490,000 psi) are significantly higher than the TTC measured values (182,622 to 340,044 psi). This introduces the possibility that some differences in modulus may occur through variations in sample creation, preparation, testing procedures, and/or interpretation. In particular, for the Columbus 8-in. QA/QC sample, the sample is usually prepared by curing an extension of the liner within the manhole. This does not have the same installation and curing conditions as within the sewer line itself and such samples are generally expected to have higher test results than coupons cut from within the sewer. For tensile strength, the average values range between 2,300 psi and 4,020 psi. The Columbus 8-in. liner tended to exhibit high tensile strengths (3,696 psi to 4,020 psi) and the Denver 48-in. liner tested by Insituform had a low tensile strength of 2,300 psi. The remaining tensile strengths were all grouped in a close range between 2,990 psi and 3,208 psi. There is no minimum value for tensile strength provided in the ASTM F1216 standard. For tensile modulus, the average values range between 315,259 psi and 426,787 psi. There is no minimum value for tensile modulus provided in the ASTM F1216 standard and it does not appear to be a commonly recorded test value. Tensile elongation at break is sometimes used within the industry to help identify issues relating to liner composition, but it is reported to be an imprecise measure due to the effect of surface irregularities in the sample on the elongation at break. A high elongation at break may point to a lower degree of resin saturation in the liner, but good records of liner wet out and examination of specific gravity data are considered more reliable. For the test results reported in this study, the tensile elongation (strain) at break ranges from 1% to around 11%. In this study, the high elongations at break were observed for the Columbus 8-in. liner samples, but this did not appear to correlate well with poor performance in the other test values. The most common range for tensile elongation at break for the samples tested ranged from around 1.5% to around 6%. The flexural and tensile testing results raise issues about the variability of samples within the same liner and potential variability in test results among different laboratories. However, some level of correlation between test results is observed for some of the parameters measured. As the research progresses to other sites, it will be important to find out which of the parameters are the most sensitive to deterioration of the liner structural condition and performance, as well as which are the most cost-effective and reliable to measure. Most of the liner samples met the original specifications for structural performance in flexure. Even the two samples that were below the originally specified flexural modulus values appeared to be in good 99
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EPA/600/R-12/004 | January 2012 | w
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DISCLAIMER The work reported in thi
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ACKNOWLEDGMENTS This report has bee
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samples had a flexural modulus valu
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CONTENTS DISCLAIMER ...............
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4.3.10.2 Upstream Sample ..........
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9.2.2 Recommendations for Developme
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Figure 5-27. Raman Spectra for the
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ABBREVIATIONS AND ACRONYMS AMP Asse
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1.0: INTRODUCTION This report forms
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1.2 Organization of the Report Foll
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Some sections of a sewer system may
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• The depth of the pipe below the
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Figure 2-3 highlights the main diff
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The most commonly used resins are i
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the glass fiber. The tube, which is
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3.0: DEVELOPMENT OF CIPP EVALUATION
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• The municipality would be willi
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• Measurements and/or physical sa
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Table 3-3. Laboratory Evaluation an
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4.1 Introduction 4.0: CITY OF DENVE
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Figure 4-1. Images of the Recovered
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Sample ID Figure 4-4. Soil Grain Si
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Location Table 4-5. Denver 8-in. Li
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Profile Plot Red - Steel tube Green
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Table 4-7. Results from Flexural Te
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35 Table 4-9. Comparison of Test Da
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4.2.12 Buckling Test. A steel mecha
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Figure 4-18. Pressure Gage and Pres
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4.2.13 Shore D Hardness. Durometer
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Figure 4-24. Barcol Hardness Readin
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increases and the heat of cure decr
Page 65 and 66: In summary, CCTV inspection of thre
Page 67 and 68: Figure 4-28. Thickness for Denver 4
Page 69 and 70: 4.3.6.2 Downstream Sample. Seven sp
Page 71 and 72: Figure 4-34. Flexural Stress-Strain
Page 73 and 74: Table 4-18. Flexural Test Results f
Page 75 and 76: 4.3.8.2 Upstream Sample. Specimens
Page 77 and 78: 4.3.10 Barcol Hardness 4.3.10.1 Dow
Page 79 and 80: 4.3.11.2 Downstream Sample. The Ram
Page 81 and 82: 5.1 Introduction 5.0: CITY OF COLUM
Page 83 and 84: April 16, 2010 The specimen was rec
Page 85 and 86: The resulting gradation curves are
Page 87 and 88: Table 5-4. Soil pH at Designated Lo
Page 89 and 90: Figure 5-8. Average Thickness at Di
Page 91 and 92: 5.2.12 Flexural Testing. Specimens
Page 93 and 94: Figure 5-14. Flexural Stress-Strain
Page 95 and 96: Figure 5-16. Tensile Stress-Strain
Page 97 and 98: 5.2.15 Buckling Test. A mechanical
Page 99 and 100: Figure 5-24. Localized Leak on the
Page 101 and 102: Figure 5-26. Barcol Hardness Readin
Page 103 and 104: 5.3.3 Visual Inspection of Liner. I
Page 105 and 106: Figure 5-32. Ultrasonic Testing for
Page 107 and 108: Table 5-13. Geometric Data for Flex
Page 109 and 110: Figure 5-38. Shore D Hardness of Co
Page 111 and 112: 6.1 Introduction 6.0: REVIEW AND CO
Page 113 and 114: Overall, the liners appear to be ho
Page 115: age difference between the liners i
Page 119 and 120: A significantly lower range of Shor
Page 121 and 122: 7.0: RECOMMENDED TEST PROTOCOL FOR
Page 123 and 124: combining this broadly available in
Page 125 and 126: Table 7-3. Overall Structure for a
Page 127 and 128: Table 8-2. CIPP and Other Rehabilit
Page 129 and 130: Table 8-5. Rehabilitation Specifica
Page 131 and 132: 113 Table 8-9. Process Verification
Page 133 and 134: Göttingen Stadtentwässerung: Göt
Page 135 and 136: experience and quality, and do not
Page 137 and 138: km of pipe and 50-year-old pipes ar
Page 139 and 140: methods are detailed in the Guide t
Page 141 and 142: The business of pipeline rehabilita
Page 143 and 144: • Destructive testing (but will n
Page 145 and 146: In Denver, in CCTV inspections of n
Page 147 and 148: 9.2 Recommendations for Future Work
Page 149 and 150: Falter, B. 1996. “Structural Anal
Page 151 and 152: Lehmann, M.A, J.P. Schroeder and C.
Page 153 and 154: APPENDIX A LIST OF TEST STANDARDS R
Page 155 and 156: The following table lists the non-A
Page 157 and 158: B.1 Introduction This study was con
Page 159 and 160: Mean thickness values for each cont
Page 161 and 162: APPENDIX C INTERNATIONAL STUDY INTE
Page 163 and 164: The original Insituform liner insta
Page 165 and 166: However, the figures published by O
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exfiltration and infiltration. Any
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STW uses CIPP for virtually all of
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method. Top hat repairs to junction
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All design and construction supervi
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Process verification test samples a
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consultant born out of the corporat
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BW continues to use CIPP, mainly in
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East, but has not yet had marked su
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