Long-Term Pavement Performance Materials Characterization Program: Verification of Dynamic Test Systems With An Emphasis On Resilient Modulus

Equipment Availability

Check that the following items are ready prior to beginning the QC procedure:

• ___ Latest version of procedure.
• ___ Computer with sufficient hardware/software for data analysis.
• ___ Pressure gauge.
• ___ Triaxial cell and pressure system.
• ___ Loading device.
• ___ Electronic load cell.
• ___ Spring-loaded LVDTs.
• ___ Signal excitation, conditioning, and recording equipment.
• ___ All other miscellaneous equipment needed for preparing samples.
• ___ Bulk material splitter.
• ___ 152 mm diameter split mold, minimum height of 381 mm.
• ___ 71 mm diameter mold, minimum height of 152 mm.
• ___ Vibratory compaction device.
• ___ Spacer plugs for compaction of material lifts.

Electronic Systems Performance Verification Check

• ___ The electronic systems performance verification check has been successfully completed.

Calibration Check and Overall System Performance Verification Procedure

• ___ Calibration check and overall system performance verification procedure has been successfully completed.

Type 1 (Base/Subbase) Proficiency

• ___ Sample preparation is performed satisfactorily.
• ___ Moisture content within ±1 percent of specified.
• ___ Dry density within ±3 percent of specified.
• ___ Specimen is compacted according to appendix B procedure.
• ___ Porous stone and sample cap in place.
• ___ Specimen is placed in triaxial chamber, with all lines hooked up, and no leakage is noted.
• ___ Triaxial chamber checked for levelness.
• ___ Initial pressure of 14 kPa applied to specimen in chamber.
• ___ Apply confining pressure of 103 kPa.
• ___ Load cell and LVDTs ready to begin testing.
• ___ Sample is not decreasing in height after preconditioning.
• ___ The type 1 (subgrade) test sequence has been performed.
• ___ Remove specimen and determine moisture content.
• ___ Triaxial pressure maintained within tolerance throughout testing.
• ___ LVDT ratios are within acceptable tolerances.
• ___ Specimen was handled appropriately throughout the test procedure.

Type 2 (Subgrade) Proficiency

• ___ Sample preparation is performed satisfactorily.
• ___ Moisture content within ±0.5 percent of specified.
• ___ Dry density within ±3 percent of specified.
• ___ Specimen is compacted according to procedure in LTPP Protocol P46.
• ___ Porous stone and sample cap in place.
• ___ Specimen is placed in triaxial chamber, with all lines hooked up, and no leakage is noted.
• ___ Triaxial chamber checked for levelness.
• ___ Initial pressure of 14 kPa applied to specimen in chamber.
• ___ Apply confining pressure of 41 kPa.
• ___ Load cell and LVDTs ready to begin testing.
• ___ Sample is not decreasing in height after preconditioning.
• ___ The type 2 (subgrade) test sequence has been performed.
• ___ Remove specimen and determine moisture content.
• ___ Triaxial pressure maintained within tolerance throughout testing.
• ___ LVDT ratios are within acceptable tolerances.
• ___ Specimen was handled appropriately throughout the test procedure.

Equipment Availability

Check that the following items are ready prior to beginning the QC procedure.

• ___ Latest version of procedure.
• ___ Computer with sufficient hardware/software for data analysis.
• ___ Environmental chamber and temperature control system.
• ___ Loading device.
• ___ Diametral loading heads and specimen restraint system.
• ___ Gauge points.
• ___ Contact point template.
• ___ Gauge point mounting system.
• ___ Humidity cabinet.
• ___ Data reduction and analysis system.
• ___ LVDT calibration unit.
• ___ Electronic load cell.
• ___ Extensometers (4).
• ___ Signal excitation, conditioning, and recording equipment.
• ___ All other miscellaneous equipment needed for preparing samples.
• ___ Masonry saw capable of cutting smooth surfaced specimens.

Electronic Systems Performance Verification Check

• ___ The electronic systems performance verification check has been successfully completed.

Calibration Check and Overall System Performance Verification Procedure

• ___ Calibration check and overall system performance verification procedure has been successfully completed.

Proficiency Testing

Sample Preparation

• ___ Cores for testing have visible cracks or deformed in any manner.
• ___ Specimens for test of one pavement layer.
• ___ Specimens from one area of test specimen.
• ___ Top and bottom surfaces trued as necessary.
• ___ Test specimen greater than 25.4 mm but less than 53.3 mm in thickness.
• ___ Core examination and thickness performed.
• ___ Bulk specific gravity performed.
• ___ Bulk specific gravities similar for the three candidate test specimens.
• ___ Thickness measurement conducted by averaging four measurements located at quarter points around the sample perimeter and 13 to 25 mm in from the edge.
• ___ Diameter measured (1) along the axis parallel to the direction of traffic and (2) the axis perpendicular to the axis measured in (1).
• ___ Diameter = 97.8 mm or = 105.4 mm.
• ___ Diametral axis marked with loading head contact template.
• ___ Specimen sawn to provide smooth, parallel surfaces for mounting the measurement gauges.
• ___ Gauge points attached per protocol.
• ___ Samples’ temperature and moisture conditioned properly before test.
• ___ Core samples in the cabinet/chamber for a minimum of 24 hours before testing at 5 °C and 25 °C.
• ___ Specimens held at 40 °C for a minimum of 3 hours, but not exceeding 6 hours, before testing.
• ___ Specimens stored in an environment where the temperature is maintained between 5 and 21 °C until they are to be conditioned for testing.
• ___ Deformation devices mounted on sample and zeroed/rebalanced before test.

Creep Compliance Testing

• ___ Load strip alignment mark on test specimen located in line of action of actuator shaft and loading strips (back and front).
• ___ Specimen to strip surface in a contact condition (no obvious projections or depressions).
• ___ Static load of fixed magnitude applied without impact to specimen.
• ___ Fixed load produce horizontal strain of 150 to 350 micro strain.
• ___ Constant static load within 2 percent of required loading during entire test procedure.
• ___ Reasonable deformation response.
• ___ Data collected at 10 Hz for first 10 s and 1 Hz for remaining 90 s.
• ___ Initial load level achieved at end of test.
• ___ Three temperatures achieved and within tolerance.

Resilient Modulus Testing

• ___ Deformation devices zeroed or rebalanced prior to start of test.
• ___ Correct haversine waveform produced.
• ___ Reasonable deformation response.
• ___ Horizontal strain in the 150 to 350 micro strain range.
• ___ Data collected uniformly at 500 Hz.
• ___ Five load cycles recorded.
• ___ All three temperatures achieved and within tolerance.

Strength Testing

• ___ All other testing complete and results checked prior to commencing test.
• ___ Test performed at the correct temperature and within tolerance.
• ___ Deformation devices zeroed or rebalanced prior to start of test.
• ___ Load applied to specimen correctly.
• ___ Data collected at 1 Hz.
• ___ Test stopped when load begins to decrease.

Calculations

• ___ Calculations performed completely and accurately.

Completion of Data Forms

• ___ Calculations performed completely and accurately.