Ancillary NDT Research Findings From NAPTF by 81jnAQ

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									    NDT Research
Findings From NAPTF

 April 24, 2012 Working Group


     Roy D. McQueen, P.E.
Roy D. McQueen & Associates, Ltd.

      rdmcqueen@rdmcqueen.com
          Acknowledgements
   Gordon Hayhoe, PhD
   Josh Davis
   Jason Tarby
   Mike Loev
                      TOPICS
   Force Linearity

   CBR/k correlations

   BAKFAA demonstration

   Future enhancements
                     Evaluation of HWD Force Linearity - ISM

      2,500


              12, 24, 36 kip
                                    HFS
              Applied Force
      2,000
                                                               HFS

                           MFS
               LFS                                      MFS
      1,500
                                                  LFS
ISM




      1,000




       500




         0
                                          Test1Item
                                  Evaluation of HWD Force Linearity - Subgrade Modulus

                         40,000


                                                        HFS                              HFS
                         35,000




                         30,000
                                  12, 24, 36 kip
                                  Applied Force
Subgrade Modulus (psi)




                         25,000




                         20,000


                                            MFS                                 MFS
                         15,000
                                                                          LFS
                                  LFS
                         10,000



                          5,000




                             0
                                                                  1
                                                              Test Item
                               NATIONAL AIRPORT PAVEMENT TEST FACILITY
                                            E-CBR Equation


          60,000




          50,000
                                                                E= 1500CBR



          40,000

                          Typical CBR Range
E (psi)




          30,000

                                                                E = 3363.2(CBR)0.6863
          20,000
                                                                     R2 = 0.9727



          10,000




             -
                   0.0   5.0       10.0     15.0   CBR   20.0   25.0      30.0     35.0   40.0
                                    Figure 3. E and k-value Conversion

                           160
Subgrade k-value, psi/in




                           140
                           120
                                                                         BAKFAA-
                           100
                                                                         Closed_form
                            80
                                                                         E=26*k^1.284
                            60
                            40
                            20
                             0
                             7000    9000     11000    13000   15000
                                         Subgrade E, psi
                       To Do
   Boundary conditions for layer moduli

   Seed values to start back-calculations

   Further investigate CBR to k correlations

   Hard bottom guidance
Questions?

								
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