Daba S. Gedafa, Ph.D., P.E.University of North Dakota

Perpetual pavements limit strains at the bottom of the asphalt concrete layer

Surface deflection testing is widely used for pavement structural evaluation

Deflection testing at the network level can: identify the beginning and end of management sectionsgroup pavement sections with similar structural capacities

to make “families”

E17: ASTM International Symposium 2011 2

Falling weight deflectometer (FWD) is the most popular device for project-level deflection testing

Network-level FWD testing is unsafe, time consuming, and expensive

Rolling wheel deflectometer (RWD) measures surface deflections at highway speed

E17: ASTM International Symposium 2011 3

RWDARA RWD and Close-up of Laser D

E17: ASTM International Symposium 2011 4

Spatially Coincident Profiles

E17: ASTM International Symposium 2011 5

Compare FWD and RWD center deflections and corresponding effective structural numbers (SNeff)

Establish the relationship between FWD and RWD center deflections and corresponding SNeff

E17: ASTM International Symposium 2011 6

E17: ASTM International Symposium 2011 7

Section 1 2 3 4

Acronym KAPA

(Standard)

KAPA

(High Reliability)

KAPA 2

(Modified)KDOT

Surface Course 40 mm, SM 9.5 A (PG70-28)

Binder Course 60 mm, SM 19 A (PG70-28)

Base Course225 mm, SM

19A (PG70-22)

187.5 mm, SM 19

A (PG64-22)

225 mm, SM 19

A (PG64-22)

300 mm, SM 19A

(PG64-22)

Stabilized

Subgrade150 mm, 6% hydrated lime mixed with natural soil

Natural

SubgradeHigh plasticity clay (A-7-6)

Deflection:FWDRWD

Pavement temperature

E17: ASTM International Symposium 2011 8

Pavement temperature

Deflection correction

Pavement structural capacity

Significant difference test

Linear regression

E17: ASTM International Symposium 2011 9

E17: ASTM International Symposium 2011 11

0

5

10

15

20

25

30

35

40

45

Wat

son

Lela

nd

BELL

S3

Mea

sure

d

Wat

son

Lela

nd

BELL

S3

Mea

sure

d

Wat

son

Lela

nd

BELL

S3

Mea

sure

d

Wat

son

Lela

nd

BELL

S3

Mea

sure

d

S1 S2 S3 S4

Ave

rage

Pav

emen

t Tem

pera

ture

(o C)

Section and Method

E17: ASTM International Symposium 2011 12

0.00

0.05

0.10

0.15

0.20

0.25

0.30

Avg Min Max Avg Min Max Avg Min Max Avg Min Max

S1 S2 S3 S4

Cen

ter

Def

lect

ion

(mm

)

Section

FWD RWD

E17: ASTM International Symposium 2011 13

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

Avg Min Max Avg Min Max Avg Min Max Avg Min Max

S1 S2 S3 S4

SNef

f

Section

FWD RWD

E17: ASTM International Symposium 2011 14

y = 0.8478x + 0.039R² = 0.5462

0.14

0.16

0.18

0.20

0.22

0.24

0.26

0.28

0.14 0.16 0.18 0.20 0.22 0.24 0.26 0.28

RW

D C

ente

r D

efle

ctio

n (m

m)

FWD Center Deflection (mm)

E17: ASTM International Symposium 2011 15

y = 0.1905x + 3.7392R² = 0.0315

4.0

4.2

4.4

4.6

4.8

5.0

5.2

5.4

4.0 4.2 4.4 4.6 4.8 5.0 5.2 5.4

RW

D S

Nef

f

FWD SNeff

BELLS3 equation gives a mid-depth pavement temperature close to the measured value

No significant differences between center deflections and corresponding effective structural numbers from RWD and FWD deflection data

There is:a linear relationship between FWD and RWD center

deflectionsno linear relationship between FWD and RWD SNeff

E17: ASTM International Symposium 2011 16

Federal Highway Administration

Kansas Department of Transportation (KDOT)

Applied Research Associates (ARA)

Mustaque Hossain, Ph.D., P.E., KSU

Richard Miller, P.E., KDOT

Douglas Steele, P.E., ARA

E17: ASTM International Symposium 2011 17

Contact:Daba S. Gedafa, Ph.D., P.E.University of North Dakota

E-mail: daba.gedafa@engr.und.eduOffice Phone: 701-777-3976

E17: ASTM International Symposium 2011 18