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88th Annual Meeting - January 11-15, 2009
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Backcalculation of Pavement Layer Moduli Subcommittee, AFD80(1)
Monday, January 12, 2009, 1:30 PM - 3:15 PM, Marriott
Lynne H. Irwin, Cornell University, presiding

Sponsored by:
Strength and Deformation Characteristics of Pavement Sections Committee (AFD80)

1:30 Welcome; Self-introductions
Brief Reports:
1. Progress with Pooled-Fund Study TPF-5(039) "Falling Weight Deflectometer (FWD) Calibration Center and Operational Improvements" L H Irwin
2. Progress on revisions and balloting for AASHTO R 32 "Standard Recommended Practice for Calibrating the Load Cell and Deflection Sensors for a Falling Weight Deflectometer" L H Irwin
3. FHWA plans for a new research project: "Relationships Between Laboratory-Measured and Field-Derived Properties of Pavement Layers" Jane Jiang, FHWA
4. Update on project: "Using FWD Data with Mechanistic-Empirical Design and Analysis" Dr. Nadarajah "Siva" Sivaneswaran, FHWA (tentative presenter)
Committee Business:
5. Invitation to membership on the subcommittee
6. Discussion of proposed revision of subcommittee name (see back of this page)
7. Discussion of proposed subcommittee scope statement
Discussion of Potential Future Subcommittee Projects:
8. Effects of FWD type and performance characteristics on backcalculated moduli and mechanistic overlay design outcomes group discussion
o Collection of data sets (volunteer agencies needed)
o Posting of data
o Analysis methods
o Use of results in overlay design
o Reporting of results
9. Effects of precision and bias on the accuracy of backcalculated moduli and mechanistic overlay design outcomes Richard Stubstad, ARA
o Theoretical study begin with a calculated deflection basin for which the layer moduli are known
o Randomly add increments of error to the calculated deflections
o Suggested ranges: random error 0.5 to 3 microns; systematic error 0.3 to 3 percent of peak deflection
o Volunteers needed to present results in a paper session at 2010 Annual Meeting
10. Other Business (as time permits)
o Possibly sponsor and organize a Backcalculation Conference through TRB in a future summer?
3:15 Adjourn
Proposed New Subcommittee Name
Evaluation and Characterization of Pavement Layers for Mechanistic Pavement Design
Proposed Scope Statement
This subcommittee addresses the characterization of pavement layers and materials for mechanistic design, with an emphasis on methods for evaluation of the underlying layers including subgrades that cannot be directly observed from the surface. Among the interests of the subcommittee are the use of deflection data analysis techniques (backcalculation) to assess material model parameters; spatial and seasonal variations of pavement layer moduli; evaluation of NDT methods for measurement of surface and subsurface deflections and related pavement responses; evaluation of laboratory and field measurement techniques; quality of the data and its effect on mechanistic pavement design; and constitutive modeling, correlations, and other methods for determining mechanistic pavement design inputs for bound and unbound pavement layers and subgrades.

Subject Areas:
Pavement Management


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