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Diamond Grinding

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					Diamond Grinding
    By Dulce Rufino Feldman
Office of Rigid Pavement Materials and
    Structural Concrete, METS-DES




     2009 California Pavement
     Preservation Conference
                Overview
Diamond grinding background
Grooving versus grinding
Why and when diamond grinding?
Advantages
  Smoothness
  Noise
  Friction
Existing diamond grinding studies
Diamond grinding equipment
Conclusions
  Diamond grinding background
First used in California in 1965
   19-year old section of I-10
   Purpose: eliminate significant faulting
   Source: Neal and Woodstrom (1976)
Pavement received additional CPR in 1983 and
1997
   Grinding to restore the rideability and skid
   resistance of the surface
Since 1965 the use of diamond grinding has
grown to become a major element of concrete
pavement preservation
Diamond grooving versus grinding
             Diamond Grooving
   Saw blade thickness
        (2.5 mm)               19 mm




               3.2 - 6.4 mm


             Diamond Grinding
                         Width of diamond blades
                         (2.5 to 3.3 mm)



                    Land area - 2.0 mm for hard aggregate
                              - 2.8 mm for soft aggregate
    What is diamond grooving?
Operation to create discrete grooves in surface
using diamond saw blades
Purpose
   Provide drainage channel for water
   Reduce hydroplaning
   Reduce wet-weather accidents (60 to 75%
  reduction in wet-weather accidents)
    What is diamond grinding?
Removal of thin hardened concrete surface layer
using closely spaced diamond saw blades
mounted on the high speed rotating drum of a
grinding machine
What is diamond grinding? (cont.)
Most effective with other CPR techniques:
   Full-depth repair
   Dowel bar retrofit
   Joint resealing
Essential part of any concrete pavement
preservation program
       Why diamond grinding?
Reduce roughness
  Faulting
  Wheelpath “rutting”
  Built-in curling/warping
  Cracking
Adjust cross slope
Reduce noise level
Improve safety
  Surface texture
  Skid resistance
  Lane-shoulder drop off
     When diamond grinding?
Unacceptable levels:
  Roughness
  Faulting
  Noise
Safety concerns
Advantages of diamond grinding
Improves smoothness
   IRI ~70 in/mi (CA study)
Reduces pavement-tire noise level
   OBSI ~ 3 dBA (CA study)
Increases longevity
   ~17 years (CA study)
Lowers agency costs
   Cost-effective preservation technique
Lowers user costs
   Better fuel efficiency
   Less vehicle maintenance
Advantages of diamond grinding (cont.)
  Enhances surface friction and safety
  Accomplished during off-peak hours
    Short lane closures
    One lane at a time
  No clearance issues at structures
  Restores surface consistency
  Environmentally friendly
    Residues vacuumed and recycled
       Smoothness

IRI


IRI2
                     ΔIRI
                ΔT
IRI1

IRI0



           T1    T2         T3 Time
  Why smooth pavements last longer?

      Rough profile                         Smooth profile
           wavelength

                        amplitude
Profile                               Profile

27+ kips                              27+ kips
                         Wheel load                    Wheel load
18 kips                               18 kips


                    Distance                       Distance
                  Noise levels

            110
OBSI, dBA


            104


            100
           Concrete texture types
          Transverse tine       Longitudinal tine




                   103-110dBA   101-106 dBA
Traffic
          Conventional           Next generation of
          diamond grinding       concrete surface




                   100-104dBA    99-101dBA
Concrete noise levels in California




       Caltrans         Caltrans new
       rehabilitation   construction
       techniques
Acoustic durability




         Noise level, dBA
                                      Asphalt

                                       Concrete




                            Pavement age, years
Surface texture and friction ⇒ Safety
 Longitudinal texture:
   Provides directional stability
   Reduces hydroplaning (side-force friction)
   Provides “escape route” for water (trapped
   between tire and pavement surface)
 Grinding effect on accident rates in Wisconsin
 (Drakopoulos et al. 1998)
   Reduced by 40% over a 6-year period
   Reduced by 57% in wet weather conditions
              Splash and spray
                               Longitudinally
        ARFC                   grooved concrete




Phoenix, AZ, on March 2006 after 143 days without rain.
Effectiveness of diamond grinding
Depends on
  Roughness before grinding
  Quality of grinding

   Satisfactory         Unsatisfactory
Caltrans diamond grinding studies
Effect on longevity (29 Caltrans projects)
                                            2.5
                                                                                                ΔIRI = e0.0345xGL
                                                                                                 R2 = 0.9189
 IRI before grinding / IRI after grinding




                                            2.0
                                                      Average IRI ratio: 1.77 (165→93 in/mile)


                                            1.5


                                            1.0


                                            0.5
                                                                                          Longevity ~ 17 years
                                            0.0
                                                  0       2      4     6      8     10     12       14      16      18
                                                                 Time after grinding, years
               Effect on smoothness (I-635 Texas)

               250
                                           Before grinding: 698 bumps
IRI, in/mile




               200

                                                          Average: 152
               150


               100
                                                            Average: 61
                50
                     After grinding: 29 bumps

                 0
               Effect on smoothness (Caltrans data)
                         I-5 near Grapevine
               160
                     151.9
               150
               140
                                           39.9
               130
IRI, in/mile




               120                                   116.7
                               112.5
               110
                                                                            26.8
               100
                                                                     89.9
                90
                80
                70
                60
                         SB (L1)                           SB (L2)
                              Before grinding     After grinding
Effect of smoothness on fuel efficiency
            (Caltrans data)
                                                            18.0
                        (Adjusted for headwind & airflow)
Fuel consumption, mpg




                                                                                            FC = -0.0061xIRI + 17.15
                                                            17.5
                                                                                                    R2 = 0.41

                                                            17.0

                                                            16.5                                                 ~0.3 mpg

                                                            16.0

                                                            15.5

                                                            15.0
                                                                   50   75   100      125         150      175         200
                                                                                   IRI, in/mile
                  Effect on noise (Caltrans data)
            110
                          -1.2          -2.1                          -2.5
            105                                            -2.6                     -3.2         -4.4
            100
             95
OBSI, dBA




             90
             85
             80
             75
             70
             65
             60




                                                                                           Bernardino)
                    Bernardino)




                                  (Riverside)



                                                   I-5 (Orange)




                                                                  (Orange)
                    SR-60 (San




                                                                              I-5 (Ken)



                                                                                            I-5 (San
                                                                    I-405
                                      I-15




                                           Before grinding        After grinding
Effect on skid resistance (Arizona DOT)
                           0.8
                                                                    +0.20      +0.18     +0.14
                           0.7                          +0.10
 Coefficient of friction


                                    +0.13     +0.08
                           0.6
                           0.5
                           0.4
                           0.3
                           0.2
                           0.1
                            0
                                 S1 (L1)    S1 (L2)   S2 (L3)     S3 (L1)   S3 (L2)    S4 (L3)
                                                      Section (Lane)
                                                Before grinding    After grinding
           Purdue research
Optimize grinding
   Blade spacing
   Blade width
   Depth
Joint effect
   Joint opening
   Joint faulting
Innovative surfaces
   Noise
   Friction
       Diamond grinding equipment
              Basic components
    Hydraulic cylinder    Grinding machine frame




 Trailing bogies                  Leading bogies
                             Sub-frame
Depth-control wheels
                            Grinding head
Diamond grinding: equipment
Diamond grinding: equipment (cont.)
Diamond grinding: cutting head
      Setting up grinding head
Select blade spacing based on aggregate
hardness
   Hard (close spacing)
   Soft (wide spacing)
Do not line up blade segments to avoid vibration
Blade spacing affects the longevity of the
diamond ground surface
            Aggregate hardness


Soft                Medium          Hard
Limestone           River gravel   Granite, Flint
Dolomite            Trap rock      Chert, Quartz
Coral, River gravel Granite        River gravel
Number of blades: 60 versus 52 per foot
Diamond grinding: finished product
               Conclusions
Typical surface life of 10 to 16 years, depending
on climate and traffic
Usually concrete pavements can be ground up
to 3 times without affecting fatigue life
Diamond grinding:
   Eliminates faulting
   Increases friction
   Reduces pavement-tire noise
   Is a key preventive maintenance tool
          Acknowledgments
International Grinding and Grooving
Association (IGGA)
Southwest Chapter of the American Concrete
Pavement Association (ACPA)
Applied Research Associates (ARA)
California Department of Transportation
(Caltrans)

				
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posted:7/5/2011
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