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Development of infrared and radar technologies for identifying mixture segregation

Development of infrared and radar technologies for identifying mixture segregation

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Development of infrared and radar technologies for identifying mixture segregation

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  1. Development of infrared and radar technologies for identifying mixture segregation Rick Collins (TxDOT)

  2. . Background to Thermal Segregation • Historically segregation thought of as mechanical (gradation) phenomenon • 1996 – WSDOT discovered thermal imaging could detect segregation • Cold spots became low density areas • 89 percent of locations with t > 25 F failed density uniformity criteria Thermally segregated locations holding water (courtesy WSDOT)

  3. NCAT (2000) and TTI (2002) similarly found thermal uniformity suitable for detecting segregation • NCAT – low severity segregation when t > 18 F • TTI – when t > 25 F, TxDOT density uniformity requirements not met

  4. Implementing IR into Specifications • Existing methods using handheld IR devices already in place • Pave-IR system developed through research collects full-coverage testing without operator attendance

  5. Moba Corporation refined and now manufactures Pave-IR. This device is commercially available • Thermal profile and results available real time • Desktop software for viewing data files and generating pdf report Summary Results in Operacion Thermal Profile View in Operacion Reviewing Thermal Profile with Desktop Software

  6. Implementing IR into Specifications • In 2010 the use of Pave-IR is now included in TxDOT Special Provision 341-024 • Pave-IR automatically processes data and generates report • Currently 12 Pave-IR systems purchased by Contractors and in use in Texas

  7. Background to Ground Penetrating Radar • Sends pulses into pavement – non contact and high speed • Reflections obtained at interfaces of materials with different electrical (dielectric) properties • Traditionally used for thickness estimates and locating subsurface defects and section changes

  8. Using GPR for Evaluating HMA Construction • TxDOT has extensive experience using GPR and an active GPR program • In-house software for data processing • The amplitude of the Surface reflection is related to density of the HMA surface layer

  9. Plan Profile View of expected Air Void Distribution

  10. Using IR and GPR Together • IR serves well as QC with real-time monitoring • GPR serves as a QA check on completed projects GPR Collecting Data IR Bar Installed in a Paver