1. 1 Mechanical System Verification LVDT Calibration Use NIST traceable micrometer Eight point calibration Acceptance Criteria – Near zero intercept – R-squared > 0.99

2. 2 Mechanical System Verification Load Cell Zero Use strain indicator Measure load cell zero reading Used to determine if load cell has been fatigued or overstrained Acceptance Criteria – Zero reading < 1.5 % of full-scale sensitivity

3. 3 Mechanical System Verification Load Cell Calibration Certificates Check laboratory documentation to determine last NIST traceable calibration Acceptance Criteria – NIST traceable calibration within one year

4. 4 Mechanical System Verification Load Cell Calibration Verification Requires NIST traceable proving rings Utilizes static loading Verifies load cell calibration Measures unwanted friction Measures unwanted bending and deflections

5. 5 Mechanical System Verification Load Cell Calibration Verification Procedure –Apply static (ramp) load from 10 - 90% of proving ring capacity @ 10% intervals –Register load cell/LVDT readings with data acquisition system –Read dial gauge on proving ring

6. 6 Mechanical System Verification Load Cell Calibration Verification Acceptance Criteria –Proving ring versus load cell value within ± 5% of each other –Proving ring dial gauge versus LVDT reading within ± 5% of each other

7. 7 Mechanical System Verification Dynamic Response Verify overall equipment ability to conduct Resilient Modulus testing –Verify data acquisition process –Verify data format

8. 8 Mechanical System Verification Dynamic Response Procedure –Remove dial gauge from proving ring –Use external LVDTs or internally mounted LVDT for displacement measurements –Apply haversine shaped load pulse (.1 seconds on,.9 seconds off)

9. 9 Procedure (continued) –Apply dynamic load from 10 - 90% of proving ring capacity @ 10% intervals –Read deformation using data acquisition system Mechanical System Verification Dynamic Response

10. 10  Acceptance Criteria  Generated haversine close to ideal  Deformation response close to haversine  Deformation within 5% of standard  R-square > 0.99 .002 second or less phase shift between load and deformation  Ymax/Ymin < 1.10 (10%) Mechanical System Verification Dynamic Response

11. 11 Dynamic sinusoidal tests –Verify overall system electronics (phase angle measurements) –Detect misalignment problems through the use of phase angle measurements Mechanical System Verification Phase Angles Acceptance Criteria – Phase angle < 2.8 degrees

12. 12 Procedure –Use autonomous pressure reading device to verify pressure Mechanical System Verification Triaxial Pressure Chamber Acceptance Criteria – Gauge readings ± 2.5 % of target values – Hold for 10 minutes

13. 13 The 3-Phase Startup Process Verification of Electronic System Verification of Mechanical System Verification of Laboratory Ability to Conduct P46 Resilient Modulus Test

14. 14 Laboratory Proficiency Testing Focuses on laboratory ability (personnel/equipment) Sample preparation Operator’s ability to conduct a test Proper sequence and magnitude of loading Proper data format Analysis of raw data to detect any discrepancies Investigation of within and between laboratory variability

15. 15 Laboratory Proficiency Testing Acceptance Criteria –Vertical deformations within 30% –Approval by Representative based on visual observations –Conformance to all aspects of the protocol –Haversine wave form close to ideal –Deformation response reasonable –Resilient Modulus relationship reasonable

16. 16 PRESENTATION OBJECTIVES What is the Resilient Modulus (M r ) Startup Procedure Product Line Why M r Testing and the Startup Procedure is Important Development of the M r Startup Procedure How to Conduct the M r Startup Procedure How to Get Information on the M r Testing and Startup Product Line Who Should Use the M r Testing and Startup Product Line and Why

17. 17 Who Should Use the Product? Any organization performing resilient modulus testing –State DOT’s –Universities –Consultant laboratories Can be used for other tests as well –Complex modulus –Creep compliance –Indirect tensile testing, etc.

18. 18 When Should Product Be Used? General –Prior to starting a testing program –Every year during production testing –After a period of system inactivity Other recommendations –Verify the operation of older machines for new applications –When equipment is replaced –When equipment is moved –Whenever a suspected overload or malfunction occurs

19. 19 Uncover and Avoid Problems Electronics Over-ranged load cell Inadequate filters –Amplitude roll off: 2 Hz - 50 Hz Unmatched filters –Excessive time delay (phase angle) between channels –Filters on and off

20. 20 Uncover And Avoid Problems Software Software not controlling the load adequately Inadequate sampling rate Raw data with no units Automatic gain control, error range too big Lack of gain control adjustment during testing Improper raw data format - command values were saved rather than the feedback values

21. 21 Uncover And Avoid Problems Mechanical System not fast enough to apply proper haversine loads - complete upgrade of signal conditioning and control Oversize servo-value Friction in servo-value piston Friction in triaxial cell seals Misalignment caused by improperly designed triaxial cell fixture Excessive deformation, up to 76% of total deformation due to bending of triaxial cell base plate

22. 22 Uncover And Avoid Problems Mechanical (continued) Excessive deformation due to unrestrained triaxial cell Slippage of LVDT holders Lack of control of pressure transducer Malfunction of air pressure regulator

23. 23 Benefits of Use Provides guidelines for standardization of test process Provides a benchmark performance standard for equipment Minimizes equipment and operator variability Promotes greater confidence in resilient modulus testing and resulting pavement design

24. 24 Current Status of Product P46 test procedure established Videos produced and distributed Startup procedure published Startup procedures completed –FHWA –Kansas –North Carolina –Minnesota –University of Rhode Island –Consultant laboratories

25. 25 PRESENTATION OBJECTIVES What is the Resilient Modulus (M r ) Startup Procedure Product Line Why M r Testing and the Startup Procedure is Important Development of the M r Startup Procedure How to Conduct the M r Startup Procedure Who Should Use the M r Startup Procedure and Why How to Get Information on the Mr Startup Procedure?

26. 26 Get and Use M r Testing and Startup Procedure Product Line Download procedure manuals from – LTPP homepage at www.tfhrc.gov Order procedure manuals/videos: –Through LTPP homepage –Through LTPP customer service (Tel Number: 865-481-2967)