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TechBrief: Advanced Methods for Using FWD Deflection-Time Data to Predict Pavement Performance

Primary Topic: Pavement Maintenance

Description: An important property of materials that defines the viscoelastic and inelastic characteristics of materials is the dissipated work or dissipated energy of the material. Dissipated energy is simply defined as the area included in the loaded and unloaded portion of the stress-strain curve (referred to as the hysteresis loop). Dissipated energy has been used in the asphalt concrete fatigue area for many years by some agencies. Similarly, the falling-weight deflectometer (FWD) load deflection-time data can be used to measure the dissipated work during the loading and unloading of the pavement structure from the FWD impact load. This dissipated work should be related to the occurrence of selected surface distresses, especially for asphalt concrete-surfaced pavements.

The deflection-time history data collected within the Long-Term Pavement Performance (LTPP) program represent an invaluable data source and critical data element that has yet to be thoroughly investigated and used to its full potential in pavement diagnostic studies. As such, a limited study was undertaken under contract number DTFH61- 95-C-00029 to determine if there is any relationship between the dissipated work as measured with the FWD and levels of pavement distress. This study also shows some of the different parameters that can be used from the deflection-time data and the benefit of using these data for pavement diagnostic studies and pavement classifications.

FHWA Publication Number: FHWA-RD-97-093

Publication Year: 1997

Document Links: PDF (file size: 0.1 mb)

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