Improving the Accuracy and Usability of Iowa Falling Weight Deflectometer Data

Project Details
STATUS

Completed

START DATE

08/31/11

END DATE

08/31/12

RESEARCH CENTERS InTrans, CTRE, PROSPER
SPONSORS

Federal Highway Administration State Planning and Research Funding
Iowa Department of Transportation

Researchers
Principal Investigator
Halil Ceylan

Director, PROSPER

Co-Principal Investigator
Kasthurirangan Gopalakrishnan

Associate Director, PROSPER

Co-Principal Investigator
Sunghwan Kim

Associate Director, PROSPER

About the research

This study aims to improve the accuracy and usability of Iowa Falling Weight Deflectometer (FWD) data by incorporating significant enhancements into the fully-automated software system for rapid processing of the FWD data.These enhancements include: (1) refined prediction of backcalculated pavement layer modulus through deflection basin matching/optimization, (2) temperature correction of backcalculated Hot-Mix Asphalt (HMA) layer modulus, (3) computation of 1993 AASHTO design guide related effective SN (SNeff) and effective k-value (keff ), (4) computation of Iowa DOT asphalt concrete (AC) overlay design related Structural Rating (SR) and k-value (k), and (5) enhancement of user-friendliness of input and output from the software tool. A high-quality, easy-to-use backcalculation software package, referred to as I-BACK: the Iowa Pavement Backcalculation Software, was developed to achieve the project goals and requirements. This report presents theoretical background behind the incorporated enhancements as well as guidance on the use of I-BACK developed in this study. The developed tool, I-BACK, provides more fine-tuned ANN pavement backcalculation results by implementation of deflection basin matching optimizer for conventional flexible, full-depth, rigid, and composite pavements. Implementation of this tool with the Iowa DOT will facilitate accurate pavement structural evaluation and rehabilitation designs for pavement/asset management purposes. This research has also set the framework for the development of a simplified FWD deflection based HMA overlay design procedure which is one of the recommended areas for future research.

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