FRICTIONTESTING BYIGGA

2013 RPUGLarry Scofield, P.E.IGGA

Why Is Industry Friction Testing Development and Evaluation of Test Sections to

Improve Surface Characteristics Basics on Diamond Ground Textures and

Equipment Results of Various On-Going IGGA Research

Efforts Testing of the LTPP SPS-2 Experiment

Evaluation of Existing CDG and NGCS Test Sections Acoustic Longevity of CDG and NGCS Textures Friction Longevity of CDG and NGCS Textures

Evaluation of the Impact of Longitudinal Grooving on Friction Results Better Awareness of the Safety Benefits of Grooving Better Understanding of the Isotropic Behavior Development of More Grooved vs Un-Grooved Test Sections

Development of Improved CDG Textures 110 Spacers 120 Spacers 130 Spacers

Calibration and Verification of IGGA Equipment Functionality

Evaluate the Impact of Spacer Width on Friction Levels (110, 120, 130)

Compare Grooved and Ungrooved Surfaces

Comparison of CDG to Other Concrete Surfaces & AC Quiet Pavement Surfaces

Evaluate SPS-2 Test Sections

2

7

6

Existing NGCS

Existing Modified NGCS

2

Renewable Surface (OTCS)Friction Durability

45

39

51

40

44

39

48

42

0

10

20

30

40

50

60

Frictio

n (SN40)

1/8 Inch Groove Depth 1/4 Inch Groove Depth

2009                               2013                               2009                               2013

No Apparent Difference

5451

4446

40

35

56

5148 49

41

37

57

53

43

54

4441

0

10

20

30

40

50

60

70

Frictio

n FN

40      50      60     40       50      60                40     50      60      40      50      60                   40     50 60       40     50      60

110 Spacers                      120 Spacers                      130 Spacers

47

4240 40

34

28

46

42

3839

33

27

45

40

34

36

30

25

0

5

10

15

20

25

30

35

40

45

50

Frictio

n FN

40      50      60     40       50      60                40     50      60      40      50      60                 40     50 60       40     50      60

130 Spacers                      120 Spacers                      110 Spacers

48

40

54

39

50

38

54

36

0.0

10.0

20.0

30.0

40.0

50.0

60.0

Frictio

n Va

lue (SN40)

120 Spacers105 Spacers

2009                                    2013                                    2009                                    2013

Jury Still Out: Wider Spacers Probably Increase Friction but not by much

43.2

35.9

38.5

18.2

40.8

14.5

50.5

40.2

48.3

41.6

55.0

39.6

53.6

36.8

54.4

36.4

53.8

41.4

54.253.3 53.9

52.5

0

10

20

30

40

50

60

Frictio

n (FN40)

LongTined

Burlap Drag Textures

Not Grooved              Grooved   

Conventional Diamond Ground Textures

Not Grooved                       Grooved   

Long Broomand Long 

Groove

120         120         105        120                 120

R       S               R      S R      S                R      S      R      S                R      S       R      S      R      S       R      S         R      S               R      S    

Grooving has a dramatic effect on surfaces with low macrotexture

53.7 54.0

46.1

43.1

51.6

45.3

40.0

49.3

51.7

0.0

10.0

20.0

30.0

40.0

50.0

60.0

ARFC Before NGCS

CDG

Longitudinal Tined

ARFC After

Ribbed Tire on ARFC Ribbed Tire on Concrete Smooth Tire on All Surfaces 

Diamond Ground Surfaces are Competitive with AC and other PCCP Surfaces– There is variability

93 95

9396

94

92

9393

93

94

96

95

97

00

Location of Seasonal Monitoring Sites 

Seasonal Monitoring Site

5251 50

36

43

28

53

50

58

28

43

31

37

24

47

51 52

36

40

26

49

29

32

22

0

10

20

30

40

50

60

70

Frictio

n (FN40)

Delaware(1996)

California(2000)

550 Mix

900 Mix

Michigan(1993)

Wisconsin(1997) Iowa 

(1994)

Kansas(1992) Arizona

(1993)

R      R            R    S      R    S       R     S      R    S            R     S     R     S            R     R            R    S     R    S              R    S     R     S   

R = Ribbed Test TireS = Smooth Test Tire

Longitudinally Tined

550 psi Mixes Always Exhibited Higher Smooth Tire FN40

Work Will Continue with New Test Section Construction Planned for 2013