Pavement Scan Ground Penetrating Radar

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Pavement Scan Ground Penetrating Radar Powered By Docstoc
					Pavement Scan
Ground Penetrating Radar
The Best Tool for Pavement Inspection and
Sub-base Assessment




                            high resolution...
                                   high speed...

                                                   Revised July 2006
GPR SOLUTIONS
     Thickness
  Voids/Compaction
   Joint Condition
 Sub-grade Condition


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Company History
 Chartered in 1941
 Operating under current management since 1973
 32 years experience with NDT and NDE of
 pavements and structures
 Multi-disciplined professional organization,
 specializing in Facility Inspection & Management,
 Construction Management, Information
 Technology, Planning, and Design
 Award winning firm
 Multiple offices with over 200 employees
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What is GPR?
Ground Penetrating Radar

A Non-Destructive
inspection method
using radio waves
to penetrate into
structures, sub-
structures,
pavement, soil or
other mediums.

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What is GPR?
Radar Vision - 3D Imaging of
Pavement Structures

  Determination of Pavement            Voids
  Layer Thickness
  Determination of Voids/Density
  in Asphaltic Mixtures
  3D Imaging of Sub-structural
  Defects and Voids
  3D Imaging of Joint
  Deterioration Under Pavement
  Determination of high moisture
  accumulation
  A Non-Destructive Tool
                                   5
Why GPR?

 No Traffic Interruption
 Concrete & Asphaltic Pavements
 Determine Pavement Thickness
 Asphaltic Pavement Density & Void
 Determination
 Joint Conditions
 Subgrade Support Condition
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GPR “Insight”


                             Surface




              Bottom of
             Asphalt Layer                    Bottom of
                                            Concrete Layer
                             Base Layer




  A typical GPR Scan showing layers of pavement and air voids
    between top layer of asphalt 7and the asphalt layer below it
The Use of GPR in Assessing
Pavement




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Density / Voids




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                        Non linear Mathematical Model: %Void = 272.9 exp(-0.651 * Surface dielectric)

            14.00




            12.00




            10.00




             8.00
% of void




                                                                                                                 GPR data
                                                                                                                 Core data
             6.00




             4.00




             2.00




             0.00
                 0.00     20.00          40.00           60.00         80.00          100.00            120.00
                                                    Distance in feet

                                                                 10
                                    Thicknesses of asphalt and concrete layers

                      10


                       9


                       8


                       7
Thickness in inches




                       6

                                                                                             Asphalt
                       5
                                                                                             Concrete

                       4


                       3


                       2


                       1


                       0
                           0   50         100                      150           200   250
                                                Distance in feet

                                                            11
Joint Condition
GPR “Vision”


                       Surface
       A         B                  C                 D



                Bad Joint
   Good Joint                           Good Joints

                 Asphalt Concrete Interface



                              12
Joint Condition Survey
              Visual                   vs.               GPR




 Rated “no repair” by visual Survey          GPR shows a partial depth repair




                                        13
  Rated “no repair” by visual Survey
                                              GPR shows a full depth repair
Joint Condition Survey

      Visual    vs.                     GPR
                                                    Surface

                                      Asphalt Concrete
                                         Interface
                      Steel
                         Good condition            Bottom of
                            repaired joint         Concrete




                                                    Surface


                                               Asphalt Concrete
                      Steel                       Interface
                          Bad condition
                           repaired joint    Bottom of Concrete

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Joint Condition Survey
      Visual    vs.                      GPR

                                                   Surface
                      Asphalt-Concrete
                         Interface
                                           Steel
                                             Bottom of concrete
                                Good condition joint




                                                   Surface

                                           Asphalt-Concrete
                        Steel                 Interface


                                    Joint in        Bottom of
                                 bad condition      concrete

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Joint Condition Survey

      Visual    vs.                GPR

                                                 Surface

                      Asphalt-Concrete
                         Interface

                                         Steel
                                          Bottom of concrete
                              Good condition joint




                 16
Joint Condition Survey

               Visual                   vs.              GPR

   Rated “no repair” by visual Survey




                                              GPR shows a full depth repair


 I-71, Columbus, Ohio




                                         17
Joint Condition Survey

       Visual    vs.                 GPR
                                                  Surface



                                               Asphalt Concrete
                       Steel                      Interface

                          Bad condition
                           repaired joint   Bottom of Concrete




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Voids Under Slab
Data Collection




GPR unit (1500 MHz) in use during data collection




       Data collection for cracking and pumping investigation
                                  19
          of Apron Airport using dual 1500 MHz antennas
Subgrade Support
Data Collection




      400 MHz and 1500 MHz antennas in use during data collection
              from the parking lot area of ODOT District 6


            Air void                                  Air
                                                      voids
                                              Air voids




                                   20
Subgrade Voids


                                            Voids




  GPR Scan showing Air Voids below the pavement surface
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