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 95 APPENDIX A Survey Questionnaire QUESTIONNAIRE NCHRP Project 20-5 Topic 38-09 FY 2006 Estimating Resilient Modulus Values of ments of transportation (DOTs) have been developing and Subgrades and Unbound Pavement Materials revising existing methods for better estimation of resilient moduli properties. Background and Purpose One of the main objectives of Synthesis Topic 38-09 is to The new Mechanistic-Empirical Pavement Design Guide gather information on how various agencies determine resil- (MEPDG) and 1993 AASHTO Pavement Design Guide are ient moduli of subgrades and unbound bases and how these founded on the use of resilient modulus as the primary input properties have been used in the design of pavement sys- parameter when characterizing subgrade, subbase, and base tems. To accomplish this objective, the following question- materials. Resilient modulus values of these materials are naire is designed in three parts. Part II should be completed typically determined either by performing repeated load by the state Materials/Geotechnical engineer or agency offi- triaxial tests in the laboratory or by conducting nondestruc- cial most knowledgeable about the agency’s material testing tive tests in the field or using correlations relating moduli to practices, and Part III should be completed by the Pavement basic soil properties or other material parameters. For over Design engineer or agency official most knowledgeable 30 years, researchers and practitioners from various depart- about pavement design practices.

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96 Part I. Respondent Information 1. Which division is in charge of determining the resilient moduli of base and subgrade material for pavement design within the agency? Division: DOT: 2. Who is in charge of research or technical support/assistance or pavement design, which provides a “troubleshooting” for pavement performance problems and involves in the pavement design within the agency? Division (Research/Technical Support): Division (Pavement Design): Materials (MR ) Related Testing Information Provided by: Name:__________________________________________________________________________________________ Title:___________________________________________________________________________________________ Agency:_ _______________________________________________________________________________________ Address:________________________________________________________________________________________ City:__________________________________ State:________________________ Zip: _ _______________________ Phone:_ _______________________________ Fax:__________________________ e-mail: ______________________ _ Pavement Design Information Provided by: Name:__________________________________________________________________________________________ Title:___________________________________________________________________________________________ Agency:_ _______________________________________________________________________________________ Address:________________________________________________________________________________________ City:__________________________________ State:________________________ Zip: _ _______________________ Phone:_ _______________________________ Fax:__________________________ e-mail: ______________________ _ Please return the completed questionnaire by January 15, 2007, to: Anand J. Puppala, PhD, PE After completing the survey, if there are issues pertaining to resilient moduli of subgrades and unbound bases that you believe are not addressed by the questionnaire, please feel free to contact the author directly.

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 97 Part II. Resilient Modulus: Laboratory and Field Measurements, and Correlations 1. In how many pavement design projects per year (average) are resilient moduli properties of subgrades and unbound bases determined/measured? …… None* …… 1–10 …… 10–20 …… More than 20 per year * If you answered None, please skip the survey and provide any comments related to resilient property measurements. 2. Please indicate the types of soil that your agency has dealt with. (Check all that apply.) Soil Types Unbound Base Type …… Gravel (GW, GP)   Crushed Stone …… Coarse Sand (SW, SP)   Gravel …… Fine Sand (SP)   Crushed Concrete …… Silty Clay (MC and others)   Crushed Masonry …… Lean Clay (CL)   Lime Stone …… Fat Clay (CH)   Others Other Soil Type: Other Base Type: 3. Does your agency use laboratory methods for the determination of resilient moduli properties? (Check all that apply.) …… Yes …… No If the answer is Yes, please answer the following questions. Otherwise please skip to Question 17. IIa. Laboratory Methods 4. Who is responsible for performing resilient modulus (to be used for pavement design practice) laboratory tests? …… Geotechnical/Materials Lab …… University Lab (as a part of research subcontract) …… Outside Lab …… Other (explain): 5. Do you follow specific guidelines regarding the number of tests to be performed per volume of the subgrade/unbound base or length of the highway? Subgrade …… Yes, Please provide a few details/reference for the guidelines …… No Unbound Base …… Yes, Please provide a few details/reference for the guidelines …… No

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98 6. What laboratory method is typically used? …… Repeated load triaxial test …… Small strain shear moduli measurements using Resonant Column test …… Small strain shear moduli measurement using Bender Element test …… Others (explain): 7. What procedure is followed in performing laboratory repeated load triaxial tests? …… AASHTO T-294 …… AASHTO T-307 …… NCHRP 1-28 A Harmonized …… TP-46 …… Others (explain): If the response to the above question is Others, please answer the following Question 8; otherwise, skip to Question 9. 8. Provide more details about the test procedure followed by your agency. Subgrade …… Applied confining stresses (explain): …… Applied deviatoric stresses (explain): …… Displacement measurements (explain): …… Please list the reference/test procedure: Unbound Base …… Applied confining stresses (explain): …… Applied deviatoric stresses (explain): …… Displacement measurements (explain): …… Please list the reference/test procedure (explain): 9. Provide details on the laboratory specimens used in the resilient moduli tests. (Check all that apply.) …… Laboratory fabricated specimens for new pavement design …… “Undisturbed” field samples for pavement rehabilitation design …… Laboratory fabricated specimens for pavement rehabilitation design …… Others (explain): 10. Describe the laboratory procedures followed for specimen preparation. (Check all that apply.) Subgrade …… Impact compaction (similar to Proctor test methods) …… Static compaction/compression …… Vibratory compaction …… Kneading compaction (Gyratory type) …… Others (explain):

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 99 Unbound Base …… Impact compaction (similar to Proctor test methods) …… Static compaction …… Vibratory compaction …… Kneading compaction (Gyratory type) …… Others (explain): 11. Is any moisture conditioning of specimens performed prior to resilient modulus testing? …… No (basically tested at compaction moisture content conditions) …… Yes (please provide details): 12. How many laboratory tests are performed for each subgrade and base location to establish average moduli properties? Subgrade …… 1 …… 3 …… Others (explain): Unbound Base …… 1 …… 3 …… Others (explain): 13. Which regression model form is used to analyze the laboratory resilient moduli results? …… MR = k1. θk2 …… MR = k3. σdk4 …… MR = k5. σoctk6τoctk7 …… MR = k8. σ3k9σdk10 …… Other models (please explain the number of constants and model attributes such as confining or deviatoric or octahedral stresses): 14. How do you determine the field resilient moduli (for pavement design) from the laboratory test results? …… Use regression model with field confining and deviatoric stresses …… Apply field confining and deviatoric stresses in the lab test …… Others (explain): 15. What are the problems of the laboratory resilient modulus tests? (Check all that apply and rate the top three of them by indicating 1, 2, 3 in the comment box next to each response.) …… Repeatability problems …… Reliability problems (accuracy of measurements) …… Requires skilled personnel to conduct the tests …… Too many standards …… Too much time per test

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100 …… Expensive …… Difficulty in applying tensile stresses in the lab …… Unsure whether method provides true modulus of subgrade in field …… Others (explain): 16. What are the strong points of the laboratory resilient modulus tests? (Check all that apply.) …… Better test method …… Laboratory response is a better indicator of field performance …… Provides reliable structural number for pavement design …… Others (explain): The following questions (Yes/No) are related to calibration and verification of the test equipment. (Check all that apply.) Do you perform the equipment calibration? …… Yes, Please provide the frequency (in terms of months or tests) …… No Do you use a calibrated specimen with known moduli for verification of test measurements? …… Yes …… No 17. Does your agency use field methods for the determination of resilient moduli properties? (Check all that apply.) …… Yes …… No If the answer is Yes, please answer the following questions. Otherwise please skip to Question 31. IIb: Field Nondestructive Tests 18. Check the methods used by your agency to determine the field subgrade and unbound base moduli. (Check all that apply.) …… Falling Weight Deflectometer (FWD) …… Dynaflect …… GeoGauge …… Seismic methods …… Others: If the answer is FWD, please answer the following questions. Otherwise, skip to Question 25. In the case of multiple responses, please answer the following: FWDs 19. Explain the main intent in performing field FWD tests. …… QC/QA for indirect compaction quality evaluation for new pavement construction …… Determination of subgrade moduli for pavement rehabilitation …… To ensure laboratory moduli represents field moduli …… Determination of structural coefficients of pavement layers …… Others (explain):

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 101 20. Do you follow any specific guidelines regarding the number of FWD tests to be performed per length of the highway? …… Yes, Please provide a few details/reference for the guidelines …… No 21. Please provide the following information related to FWD tests and analysis. Manufacturer of FWD Interpretation or backcalculation software used for FWD analysis Responsible personnel/division for performing FWD tests (materials/pavements) Responsible personnel/division for analyzing FWD tests (materials/pavements) 22. Please check mark the following that can be described as limitations of FWD methods. (Check all that apply and rate the top three of them by indicating 1, 2, 3 in the comment box next to each response.) Subgrade …… Poor reproducibility of test results …… Calibration of geophones …… Requires skilled personnel to perform the tests, …… Requires skilled personnel to analyze the test results, …… Different moduli predictions with different software for the same data, …… Lack of availability of additional information such as depth of bedrock, …… No standard field testing protocols, …… No correlation with laboratory measured moduli, …… Too much time per test, …… Expensive, …… Other (please specify): Unbound Bases …… Poor reproducibility of test results, …… Calibration of geophones, …… Requires skilled personnel to perform the tests, …… Requires skilled personnel to analyze the test results, …… Different moduli predictions with different software for the same data, …… Lack of availability of additional information such as depth of bedrock, …… No standard field testing protocols, …… No correlation with laboratory measured moduli, …… Too much time per test, …… Expensive, …… Other (please specify)

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102 23. What are the strong points of the FWD tests? (Check all that apply.) …… Faster test method …… Inexpensive when compared to sampling and lab tests …… Provides results that are not affected by the boundary conditions …… Provides reliable structural number for pavement design …… Others (explain): 24. Do you recommend the use of your FWD backcalculation software for other DOTs for pavement layer moduli determination? …… Yes …… No …… Others (explain): 25. In your agency, are there any specific guidelines on how to interpret the FWD moduli? If the answer is yes, please provide the reference details and how we can get that information. …… Yes …… No Please skip to Question 32 Other Nondestructive methods (Dynaflect/seismic methods/GeoGauge/others) 26. Explain the main intent in performing these tests. …… QC/QA for indirect compaction quality evaluation for new pavement construction …… Determination of subgrade moduli for pavement rehabilitation …… To ensure laboratory moduli represent field moduli …… Others (explain): 27. Do you follow specific guidelines regarding the number of tests to be performed per volume of the subgrade/unbound base or length of the highway? …… Yes, please provide a few details/reference for the guidelines …… No 28. Do you recommend this method for other DOTs for determination of layer moduli? Subgrade …… Yes …… No …… Others (explain): Unbound Base …… Yes …… No …… Others (explain):

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 103 29. Please check mark the following that can be described as limitations of these methods. (Check all that apply and rate the top three of them by indicating 1, 2, 3 in the comment box next to each response.) Subgrade …… Poor reproducibility of test results, …… Calibration of geophones, …… Requires skilled personnel to perform the tests, …… Requires skilled personnel to analyze the test results, …… Different moduli predictions with different software for the same data, …… Lack of availability of additional information such as depth of bedrock, …… No standard field testing protocols, …… No correlation with laboratory measured moduli, …… Too much time per test, …… Expensive, …… Other (please specify): Unbound Bases …… Poor reproducibility of test results, …… Calibration of geophones, …… Requires skilled personnel to perform the tests, …… Requires skilled personnel to analyze the test results, …… Different moduli predictions with different software for the same data, …… Lack of availability of additional information such as depth of bedrock, …… No standard field testing protocols, …… No correlation with laboratory measured moduli, …… Too much time per test, …… Expensive, …… Other (please specify): 30. What are the strong points of these nondestructive tests? (Check all that apply.) …… Faster test method …… Inexpensive when compared to sampling and lab tests …… Provides results that are not affected by the boundary conditions …… Provides reliable structural number for pavement design …… Others (explain): 31. Overall, how do you assess the nondestructive field tests for moduli determination? Subgrade …… Very good, well-established procedures …… Poor reproducibility problems, needs research on analysis routines …… Poor, requires equipment modifications

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104 Unbound Base …… Very good, well-established procedures …… Poor reproducibility problems, needs research on analysis routines …… Poor, requires equipment modifications 32. Does your agency use empirical or semi-empirical correlations for the determination of resilient moduli properties? …… Yes …… No If the answer is Yes, please answer the following questions. Otherwise please skip to Question 38. IIc: Correlations 33. What type of correlations are used to determine the resilient moduli? Subgrade …… Direct correlations between resilient modulus and other soil properties Ex: M R = f (PI, % passing No.200, d50 etc.) …… Direct correlations between resilient modulus and in situ test measurements …… Ex: M R = f (SPT N values or DCP or cone tip resistance) …… Indirect correlations using constants from regression models and soil properties …… Ex: k1 or k 2 = f (PI, % passing No.200, d50 etc.) …… Others: Unbound Base …… Direct correlations between resilient modulus and other soil properties …… Direct correlations between resilient modulus and in situ test measurements …… Indirect correlations using constants from regression models and soil properties …… Others: 34. How were these correlations developed? Please provide additional details including the reference details, if available. …… Not local, from the papers published in the literature …… Not local, from the recommended AASHTO design guide, please specify the design guide reference (1972, 1986, 1993, MEPDG) …… Not local, from others …… Local, developed by the database collected over several years 35. How do you characterize the level of reliability of the correlations used by your DOT? Subgrade …… Very good …… Good …… Fair …… Poor

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 105 Unbound Base …… Very good …… Good …… Fair …… Poor 36. Do you check the correlation predictions by performing additional tests (laboratory or field nondestructive tests). If the answer is yes, please list type(s) of tests conducted for this purpose. …… Yes …… No Subgrade Unbound Base 37. Are the local correlations updated frequently? If the answer is yes, please specify the frequency time period for the updates. Subgrades …… Yes, …… No Unbound Base …… Yes, …… No 38. Overall, please check mark the following that can be described as limitations of these methods. (Check all that apply and rate the top three of them by indicating 1, 2, and 3 in the comment box next to each response.): Subgrades …… Poor predictions, …… Correlations developed from a limited database, …… Too complex, should be simplified, …… Too simple and should contain normalized stress parameters/constants, …… No proper protocols on how to use or evaluate them, Unbound Base …… Poor predictions, …… Correlations developed from a limited database, …… Too complex, should be simplified, …… Too simple and should contain normalized stress parameters/constants, …… No proper protocols on how to use or evaluate them,

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106 IId. Final Summary Questions for Geotechnical/Materials Engineer 39. Overall, please rate your satisfaction (could be your pavement design group) with respect to the methods followed to determine the resilient properties of soils/unbound bases: Subgrade …… Not satisfied …… Satisfied, but methods could still be improved …… Well satisfied Unbound Base …… Not satisfied …… Satisfied, but methods could still be improved …… Well satisfied 40. If the answer is not satisfied or satisfied, but methods could still be improved, please cite the reasons for your responses. Subgrade …… Current methodology is too complicated …… Requires simple and practical standard laboratory test procedures …… Requires simple and practical standard field FWD and other test procedures …… Others, Unbound Base …… Current methodology is too complicated …… Requires simple and practical standard laboratory test procedures …… Requires simple and practical standard field FWD and other test procedures …… Others, 41. Please identify any other issues pertaining to resilient properties of subgrades/unbound bases that you feel should be addressed in this synthesis. Part III: Pavement Design 1. When designing pavements, which method is used primarily? …… 1972 AASHTO Design Guide …… 1986 AASHTO Design Guide …… 1993 AASHTO Design Guide …… Mechanistic Empirical Pavement Design Guide (MEPDG) …… Agency-Specific Mechanistic Procedure …… Agency-Specific Empirical Procedure …… If the responses are the last two, we would like to request you to e-mail/mail the two documents. Thanks in advance.

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 107 2. What moduli property is considered true moduli for pavement design? Subgrade …… Resilient Modulus from Lab …… Resilient Modulus from Field FWD …… Other (please cite reference or provide a brief description): Unbound Base …… Resilient Modulus from Lab …… Resilient Modulus from Field FWD …… Other (please cite reference or provide a brief description): 3. Do you provide any input to Materials/Geotechnical engineers with regards to resilient modulus testing? If the answer is no, please skip this question. If the answer is yes, please provide the following details: …… Applied stresses in the lab: …… Moisture conditioning in the lab: …… Correction factor for Resilient Modulus from lab: …… Correction factor for Resilient Modulus from FWD: 4. If the stress analysis underneath a pavement shows negative (tensile) stresses either in the base or subgrade layer, what type of recommendations do you provide to Geotechnical/Materials engineer: …… No, we have not come across such problem …… Yes, but no recommendations were made …… Yes, the following recommendations are used. Please list them here: 5. What, if any, computer programs are used by your agency for design of pavements? …… Darwin …… MEPDG …… Others (list the name of program): 6. For determining the effective roadbed resilient modulus, how do you consider seasonal variations? …… By using laboratory tests on samples at different moisture content conditions …… By performing field FWD tests on subgrades at different moisture states …… Other (please cite reference or provide a brief description): 7. For characterizing the structural coefficients of unbound base, which procedures do you follow? …… Not sure, we use the pavement design software …… 1993 AASHTO Design Guide …… Other (please cite reference or provide a brief description): …… Locally developed correlation (please provide a brief description): 8. For characterizing the structural support of subgrades (either in the form of a SN or others), which procedures do you follow? …… Not sure, we use the pavement design software

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108 …… 1993 AASHTO Design Guide …… Other (please cite reference or provide a brief description): …… Locally developed correlation (please provide a brief description): 9. Overall, please rate your satisfaction (response should be in terms of design group, not in terms of an individual) with respect to the use of resilient properties of soils used in the pavement design: Subgrade …… Not satisfied …… Satisfied, but could still be improved …… Well satisfied Unbound Base …… Not satisfied at all …… Satisfied, but could be improved …… Well satisfied 10. If the answer is not satisfied or satisfied but could be improved, please mark the reasons for your responses. Also, please rank the top three of your choices. Subgrade …… Design methodology is too complicated, …… Require simple and practical standard laboratory test procedures, …… Require simple and practical standard field FWD and other test procedures, …… Require better correlations, …… Should consider using LTPP data, …… Others, Unbound Base …… Design methodology is too complicated, …… Require simple and practical standard laboratory test procedures, …… Require simple and practical standard field FWD and other test procedures, …… Require better correlations, …… Should consider using LTPP data, …… Others, 11. Please identify any other issues pertaining to resilient properties of subgrades/unbound bases that you feel should be addressed in this synthesis. THANK YOU VERY MUCH FOR YOUR HELP AND COOPERATION Please return the completed questionnaire by January 31, 2007, to Dr. Anand Puppala.