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1

Determining the Limitations of

Warm Mix Asphalt by Water

Injection in Mix Design,

Quality Control and Placement

Ala R. Abbas, Ph.D.

Ayman Ali, Ph.D.

Ahmad Alhasan, M.S.

Munir Nazzal, Ph.D., P.E.

Shad Sargand, Ph.D.

Arjun Roy, M.S.

2

Acknowledgements

Mr. David Powers (Materials Management)

Mr. Craig Landefeld (Construction

Administration)

Mr. Eric Biehl (Materials Management)

Ms. Cynthia Gerst (Research Section)

Ms. Vicky Fout (Research Section)

Ms. Jill Martindale (Research Section)

Ms. Kelly Nye (Research Section)

3

Outline

Background

Study Objectives

Research Methodology

Material Information

Results and Discussion

Conclusions

Recommendations for Implementation

Questions

Background

4

5

Background

Traditional asphalt mixtures are produced at

temperatures ranging between 300oF to 325oF

(150oC to 165oC). These mixtures are

commonly referred to as hot mix asphalt (HMA).

In recent years, there has been an increased

interest in using a new type of asphalt mixtures

called warm mix asphalt (WMA).

6

Background (Cont.)

Several WMA technologies are available:

Chemical and organic additives

Foamed asphalt binders

Foamed WMA produced by water injection

has received increased interest and use in

Ohio since it requires a one-time plant

modification and does not require the use of

costly additives.

7

Background (Cont.)

Over the last five years, the amount of foamed

WMA used in Ohio has increased to more than

50% of the total amount of asphalt mixtures

used in the state.

Key benefits of foamed WMA include:

Reduced emissions during production

Improved field compaction

Improved working conditions

Ability to use higher RAP contents

8

Background (Cont.)

Despite the previous advantages, there are

several concerns regarding the long-term

performance of foamed WMA

Main concerns:

Increased rutting due to reduced binder aging

Increased moisture-damage due to insufficient

aggregate drying

Insufficient aggregate coating

Applicability of HMA mix design to foamed WMA

9

Background (Cont.)

Therefore, research is needed to evaluate the

performance of foamed WMA and determine

the factors that affect its long-term durability.

In addition, current mix design methods and

specifications used by ODOT for foamed WMA

mixtures shall be validated or revised to ensure

satisfactory long-term performance.

Study Objectives

10

11

Study Objectives

Evaluate the factors that affect the volumetric

properties, performance, and durability of

foamed WMA mixtures.

Determine the limitations of foamed WMA

mixtures.

Identify changes to current mix design and

evaluation procedures, if any, that will be

required for foamed WMA mixtures.

12

Study Objectives (Cont.)

Evaluate current ODOT quality control and

placement procedures to determine applicability

to foamed WMA mixtures.

Identify changes to current ODOT specifications

for foamed WMA mixtures to ensure

satisfactory long-term performance.


13

14


Part 1: Performance Evaluation of Foamed WMA and HMA in the Laboratory

Part 2: Workability and Compactability of Foamed WMA and HMA

Part 3: Effect of Mix Preparation Procedure on Foamed WMA

Part 4: Performance Evaluation of Foamed WMA and HMA in the APLF

Part 5: Performance Evaluation of Foamed WMA and HMA using the MEPDG

Part 1:

Laboratory Performance

of Foamed WMA and HMA

15


16


Material Combinations

Limestone Crushed Gravel

Intermediate

PG 70-22

Surface Surface

PG 70-22 PG 64-28 PG 70-22

18

Production of Foamed WMA

Foaming

Nozzle

Binder

Tank

Air

Tank

Water

Tank

Control

Panel

Laboratory Testing Plan

19

20

Laboratory Testing Plan

Laboratory

Testing Program

Fatigue CrackingDurabilityRutting

FN

APA

E*

Low Temp. Cracking

DCSE ITS

Wet APA

Mod. Lottman

Cond. E*

21

Asphalt Pavement Analyzer (APA)

Test method: AASHTO TP 63-07

and ODOT Supplement 1057

Specimen dimensions:

2.95” height x 6” diameter

Air voids: 7 ± 1%

Testing temperature: 120°F

Hose pressure: 100 psi

Wheel load: 115 lbf

Rut depth: 5, 500, 1000,

and 8000 passes

22

Dynamic Modulus |E*| (Cont.)

22

𝐸∗ = 𝜎𝑜

𝜀𝑜 ϕ =

𝑇𝑖

𝑇𝑝 × 360𝑜

Dynamic Modulus Phase Angle

23

Dynamic Modulus |E*| (Cont.)

24

Dynamic Modulus |E*|

Test method: AASHTO TP 62-03 and NCHRP 513

Specimen dimensions: 6” height x 4” diameter

Air voids: 7 ± 0.5%

Conditioning:

Age loose mixture for 4 hours at 275oF

(short-term AASHTO R30)

Loading magnitude: 75 to 125 micro-strain

Loading frequencies: 25, 10, 5, 1, 0.5, and 0.1 Hz

Testing temperature: 40, 70, 100, and 130oF

NCHRP 513 {Annex B}

Temperature: 54.4°C

Haversine compressive

stress

Stress level: 30 psi

Loading: 0.1 sec

Rest period: 0.9 sec

FN

Tertiary failure

10,000 cycles Flow

Number

25

Flow Number (FN)

26

Modified Lottman (AASHTO T 283)

Test method: AASHTO T 283 and ODOT Supplement 1051

Specimen dimensions: 3.75” height x 6” diameter

Air voids: 7 ± 0.5%

Conditioning:

Age loose mixture for 4 hours at 275oF

Soak compacted samples in water for about 4 hours

Partially saturate to 80 to 90%

Apply one freeze and thaw cycle

Loading rate: 2 inch/min

Testing temperature: 77°F

Protocol: Roque et al. (2002)

Temperature: 10°C

Specimen: 150 mm x 50 mm

Two tests:

Resilient Modulus (MR)

[NCHRP-285]

ITS [AASHTO T 322-03]

)(2

10

ftSFEDCSE

EEFEDCSE

27

Dissipated Creep Strain Energy (DCSE)

Test method: AASHTO

T 322

Temperature: -10°C

MTS 810

Specimen: 150 mm x 50 mm

Loading: 12.5 mm/min

28

Indirect Tensile Strength (ITS)

Test Results

29

Permanent Deformation

(Rutting)

30

31

Asphalt Pavement Analyzer

0.00

0.05

0.10

0.15

0.20

0.25

0.30

1 2 3 4

Per

man

ent

Def

orm

atio

n, R

utt

ing

(in

.)

HMA Foamed WMA

12.5 mm NMAS

Limestone

PG 70-22

19.0 mm NMAS

Limestone

PG 70-22

19.0 mm NMAS

Limestone

PG 64-28

12.5 mm NMAS

Gravel

PG 70-22

32

Asphalt Pavement Analyzer

Analysis Data Statistical Factors F-value Prob.

19.0 mm, Limestone, PG 64-28

&


Mix Type 0.088 0.775

Binder Type 67.108 0.000

Binder Type × Mix Type 0.427 0.532

12.5 mm, Gravel, PG 70-22

&


Mix Type 0.219 0.653

Agg. Type 0.017 0.900

Agg. Type × Mix Type 2.700 0.139


&


Mix Type 0.136 0.722

Agg. Size 0.096 0.764

Agg. Size × Mix Type 0.868 0.379

ANOVA Results Obtained for APA Test Results

33

Dynamic Modulus, |E*|

10000

100000

1000000

10000000

1E-05 0.001 0.1 10 1000 100000

Dy

nam

ic M

odulu

s, |E

*| (

PS

I)

Reduced Frequency, f (Hz)

19.0 mm NMAS Limestone & PG 70-22 (HMA)


19.0 mm NMAS Limestone & PG 70-22 (WMA)


34

Flow Number

0

1000

2000

3000

4000

5000

6000

7000

1 2 3 4

Flo

w N

um

ber

, F

N

HMA Foamed WMA

12.5 mm NMAS

Limestone

PG 70-22

19.0 mm NMAS

Limestone

PG 70-22

19.0 mm NMAS

Limestone

PG 64-28

12.5 mm NMAS

Gravel

PG 70-22

35

Flow Number



&


Mix Type 8.220 0.046




&


Mix Type 6.170 0.056

Agg. Type 77.336 0.000



&


Mix Type 10.979 0.030

Agg. Size 43.086 0.003


ANOVA Results Obtained for FN Test Results

Moisture-Induced Damage

36

37

AASHTO T 283

0

50

100

150

200

250

300

1 2 3 4

Indir

ect T

ensi

le S

tren

gth

, IT

S (

PS

I)

HMA Conditioned HMA

Foamed WMA Conditioned Foamed WMA

12.5 mm NMAS

Limestone

PG 70-22

19.0 mm NMAS

Limestone

PG 70-22

19.0 mm NMAS

Limestone

PG 64-28

12.5 mm NMAS

Gravel

PG 70-22

38

AASHTO T 283

20%

30%

40%

50%

60%

70%

80%

90%

100%

1 2 3 4

Ten

sile

Str

ength

Rat

io, T

SR

HMA Foamed WMA

12.5 mm NMAS

Limestone

PG 70-22

19.0 mm NMAS

Limestone

PG 70-22

19.0 mm NMAS

Limestone

PG 64-28

12.5 mm NMAS

Gravel

PG 70-22

TSR = 80%

39

AASHTO T 283



&


Mix Type 3.150 0.094

Test Cond. 72.618 0.000


Mix Type × Test Cond. 0.104 0.751

Mix Type × Binder Type 3.337 0.085

Test Cond. × Binder Type 16.770 0.001


&


Mix Type 0.338 0.569

Test Cond. 15.759 0.001

Agg. Type 0.121 0.732


Mix Type × Agg. Type 3.094 0.097

Test Cond. × Agg. Type 0.229 0.639


&


Mix Type 1.175 0.294

Test Cond. 32.344 0.000

Agg. Size 0.078 0.783


Mix Type × Agg. Size 1.240 0.281

Test Cond. × Agg. Size 2.284 0.149

40

Conditioned Dynamic Modulus

10000

100000

1000000

10000000

1E-05 0.001 0.1 10 1000 100000

Dy

nam

ic M

odulu

s, |E

*| (

PS

I)

Reduced Frequency, f (Hz)


12.5 mm NMAS Limestone & PG 70-22 (HMA/Conditioned)


12.5 mm NMAS Limestone & PG 70-22 (WMA/Conditioned)

12.5 mm Limestone and PG 70-22

41

Wet Asphalt Pavement Analyzer

0

0.05

0.1

0.15

0.2

0.25

0.3

1 2 3 4

Ru

t D

epth

(in

ch)

HMA (Dry APA) HMA (Wet APA)

Foamed WMA (Dry APA) Foamed WMA (Wet APA)

12.5 mm NMAS

Limestone

PG 70-22

19.0 mm NMAS

Limestone

PG 70-22

19.0 mm NMAS

Limestone

PG 64-28

12.5 mm NMAS

Crushed Gravel

PG 70-22

42

Wet Asphalt Pavement Analyzer



&


Mix Type 0.889 0.359

Test Cond. 4.164 0.057



Mix Type × Binder Type 0.830 0.375

Test Cond. × Binder Type 0.590 0.453


&


Mix Type 0.011 0.919

Test Cond. 3.633 0.074

Agg. Type 0.158 0.696


Mix Type × Agg. Type 1.977 0.178

Test Cond. × Agg. Type 0.386 0.543


&


Mix Type 0.558 0.465

Test Cond. 2.210 0.155

Agg. Size 0.047 0.831


Mix Type × Agg. Size 0.495 0.491

Test Cond. × Agg. Size 0.063 0.804

Fatigue Cracking

43

44

Dissipated Creep Strain Energy

0.00

1.00

2.00

3.00

4.00

5.00

6.00

1 2 3 4

Dis

sipat

ed C

reep

Str

ain E

ner

gy,

DC

SE

(kJ/

m3) HMA Foamed WMA

12.5 mm NMAS

Limestone

PG 70-22

19.0 mm NMAS

Limestone

PG 70-22

19.0 mm NMAS

Limestone

PG 64-28

12.5 mm NMAS

Gravel

PG 70-22

DCSE = 0.75 kJ/m3

45

Dissipated Creep Strain Energy

ANOVA Results Obtained for DCSE Test Results



&


Mix Type 0.787 0.404




&


Mix Type 6.992 0.057

Agg. Type 2.381 0.198



&


Mix Type 0.006 0.941

Agg. Size 13.521 0.014


Low-Temperature Cracking

46

47

Low-Temp. Indirect Tensile Strength

0

100

200

300

400

500

600

700

800

1 2 3 4

Indir

ect T

ensi

le S

tren

gth

@ 1

4oF,

ITS

(P

SI)

HMA Foamed WMA

12.5 mm NMAS

Limestone

PG 70-22

19.0 mm NMAS

Limestone

PG 70-22

19.0 mm NMAS

Limestone

PG 64-28

12.5 mm NMAS

Gravel

PG 70-22

48

Low-Temp. Indirect Tensile Strength

ANOVA Results Obtained for Low-Temp ITS Test Results



&


Mix Type 27.887 0.001




&


Mix Type 0.776 0.404

Agg. Type 131.681 0.000



&


Mix Type 13.093 0.007

Agg. Size 25.440 0.001


Conclusions

49

50

Permanent Deformation

Foamed WMA mixtures exhibited slightly higher rut

depth values in the unconditioned and conditioned

APA tests, slightly lower dynamic moduli, and slightly

lower flow number values than the traditional HMA

mixtures.

However, the difference was found to be statistically

insignificant. Therefore, the rutting potential of foamed

WMA mixtures is expected to be comparable to that of

the HMA mixtures.

51


Foamed WMA mixtures exhibited slightly lower

unconditioned and conditioned ITS values and

comparable TSR ratios to the HMA mixtures in the

AASHTO T 283 test. In addition, foamed WMA

mixtures exhibited slightly higher unconditioned and

conditioned rut depth values in the APA test.

However, the effect of the mix type was found to be

statistically insignificant on the unconditioned and

conditioned ITS values as well as the unconditioned and

conditioned APA rut depths.

52


By comparing the unconditioned and conditioned APA

rut depths, it was observed that the effect of sample

conditioning was more pronounced on the HMA

mixtures than the foamed WMA mixtures. This trend

was also observed in the unconditioned and

conditioned dynamic modulus tests for some of the

mixtures.

53

Fatigue Cracking

The foamed WMA mixtures exhibited slightly lower DCSE

values than the HMA mixtures. However, the difference was

found to be statistically insignificant.

In addition, the DCSE values for all foamed WMA and HMA

mixtures were greater than 0.75 kJ/m3, which has been

suggested by Roque et al. (2007) as a minimum DCSE

threshold value to ensure satisfactory resistance to fatigue

cracking.

This indicates that both foamed WMA and HMA mixtures are

expected to have adequate resistance to fatigue cracking.

54

Low-Temperature Cracking

Foamed WMA mixtures exhibited slightly lower ITS

values at 14oF (-10oC) and comparable or slightly higher

failure strain values than the corresponding HMA mixtures.

The effect of the mix type was found to be statistically

significant on the low temperature ITS values, but not on the

failure strains.

Since the HMA mixtures had higher ITS values and similar

failure strain values to the foamed WMA mixtures, the HMA

mixtures are expected to have better resistance to thermal

cracking.

Part 2:

Workability and Compactability

of Foamed WMA & HMA

55

Testing Program

56

57

Testing Program

Workability and Compactability

Testing Plan

Workability

UA Workability Device

Compactability

SGC Data

58

Workability Device

Safety Cage

Mixing Paddle

Rotating Bucket

Motor and

Gear-Reduction

Unit

Sensors Cage

Emergency

Stop Button

Electric Box

59

Workability Device (Cont.)

Test Results

60

61

Workability

Torque = 4,160 e -0.025 Temperature

R² = 0.94

Torque = 4,385 e -0.032 Temperature

R² = 0.91

0

100

200

300

400

500

600

80 90 100 110 120 130 140 150 160

Torq

ue

(in

-lb)

Temperature (oC)

HMA (12.5 mm Limestone + PG 70-22)

WMA (12.5 mm Limestone + PG 70-22)

62

Workability

Mix

Type

Aggregate

Type

Aggregate

NMAS

(mm)

Binder

Grade

Workability

Model R2

HMA

Limestone 12.5 PG 70-22 Torque = 4,160 e-0.025 Temp 0.94


Limestone 19.0 PG 64-28 Torque = 742 e-0.012 Temp 0.79

Gravel 12.5 PG 70-22 Torque = 1,611 e-0.019 Temp 0.95

WMA



Limestone 19.0 PG 64-28 Torque = 964 e-0.018 Temp 0.75

Gravel 12.5 PG 70-22 Torque = 3,426 e-0.028 Temp 0.94

Workability Exponential Models

63

Workability

98

170

123

93

36

81

65

51

0

20

40

60

80

100

120

140

160

180

200

12.5 mm NMAS

Limestone

PG 70-22

19.0 mm NMAS

Limestone

PG 70-22

19.0 mm NMAS

Limestone

PG 64-28

12.5 mm NMAS

Gravel

PG 70-22

Torq

ue

(in

-lb)

HMA

WMA

(a)

Workability at 150oC

64

Workability

342

398

223241

179

242

159

208

0

50

100

150

200

250

300

350

400

450

500

12.5 mm NMAS

Limestone

PG 70-22

19.0 mm NMAS

Limestone

PG 70-22

19.0 mm NMAS

Limestone

PG 64-28

12.5 mm NMAS

Gravel

PG 70-22

Torq

ue

(in

-lb)

HMA

WMA

(b)

Workability at 100oC

65

Compactability

Average No. of Gyrations

Mix Agg.

Type

Agg.

Size

Binder

Type APA T283 E* ITS/DCSE

HMA Limestone 12.5 mm PG 70-22 38 36 29 41



HMA Gravel 12.5 mm PG 70-22 15 15 12 14

WMA Limestone 12.5 mm PG 70-22 43 28 29 38



WMA Gravel 12.5 mm PG 70-22 16 12 9 14

Conclusions

66

67

Workability

The foamed WMA mixtures exhibited better workability

than the traditional HMA mixtures. This was attributed

to the lower asphalt binder absorption observed for the

foamed WMA mixtures.

Another factor that might have contributed to the

improvement in workability for foamed WMA mixtures

is the presence of vapor pockets entrapped within the

foamed asphalt binder that serve to keep the binder

slightly expanded and reduce its viscosity.

68

Compactability

By comparing the compaction data obtained using the

Superpave gyratory compactor during the preparation of

the laboratory specimens, it was observed that the

number of gyrations needed to achieve the target air

void levels for the foamed WMA specimens was

relatively close to that of the HMA specimens.

This indicates that the compactability of the foamed

WMA mixtures is comparable to that of the

corresponding HMA mixtures.

Part 3:

Limitations of Foamed WMA

69

70

Test Factorial

Material Combination

WMA

Effect of Temperature Reduction

0% Agg. w(%), 1.8% Foaming w(%), 30oF Temp. Red.



Effect of Foaming Water Content:




Effect of Aggregate Moisture Content:


1.5% Agg. w(%), 1.8% Foaming w(%), 30oF Temp. Red.

3.0% Agg. w(%), 1.8% Foaming w(%), 30oF Temp. Red.

HMA

0% Agg. w(%)

APA ITS AASHTO T 283

APA ITS AASHTO T 283

Test Results

71

72

Effect of Temp. Red.

0

0.05

0.1

0.15

0.2

0.25

0.3

12.5 mm NMAS

Limestone

PG 70-22

19.0 mm NMAS

Limestone

PG 70-22

19.0 mm NMAS

Limestone

PG 64-28

12.5 mm NMAS

Crushed Gravel

PG 70-22

Ru

t D

epth

(in

ch)

HMA

WMA 30F Temp. Red.

WMA 50F Temp. Red.

WMA 70F Temp. Red.

0

50

100

150

200

250

300

350

12.5 mm NMAS

Limestone

PG 70-22

19.0 mm NMAS

Limestone

PG 70-22

19.0 mm NMAS

Limestone

PG 64-28

12.5 mm NMAS

Gravel

PG 70-22

Dry

IT

S (

psi

)

HMA

WMA 30F Temp. Red.

WMA 50F Temp. Red.

WMA 70F Temp. Red.

0

50

100

150

200

250

300

350

12.5 mm NMAS

Limestone

PG 70-22

19.0 mm NMAS

Limestone

PG 70-22

19.0 mm NMAS

Limestone

PG 64-28

12.5 mm NMAS

Gravel

PG 70-22

Wet

IT

S (

psi

)

HMA

WMA 30F Temp. Red.

WMA 50F Temp. Red.

WMA 70F Temp. Red.

0%

20%

40%

60%

80%

100%

12.5 mm NMAS

Limestone

PG 70-22

19.0 mm NMAS

Limestone

PG 70-22

19.0 mm NMAS

Limestone

PG 64-28

12.5 mm NMAS

Gravel

PG 70-22

TS

R (

%)

HMA WMA 30F Temp. Red.

WMA 50F Temp. Red. WMA 70F Temp. Red.

(a) (b)

(c) (d)

73


Performance Test

APA Rut Depth Dry ITS Wet ITS

Analysis Data Statistical Factors F-value Prob. F-value Prob. F-value Prob.

WMA, 19.0 mm, Limestone, PG 64-28

&


Binder Type 136.4 0.00 97.5 0.00 31.4 0.00

Prod. Temp. 5.5 0.02 22.8 0.00 10.0 0.00

Binder Type × Prod. Temp. 1.4 0.29 7.3 0.01 1.6 0.25

WMA, 12.5 mm, Gravel, PG 70-22

&


Agg. Type 55.3 0.00 18.8 0.00 0.0 0.91

Prod. Temp. 53.3 0.00 40.7 0.00 30.6 0.00

Agg. Type × Prod. Temp. 4.7 0.03 0.5 0.64 1.5 0.26


&


Agg. Size 4.4 0.06 3.3 0.10 4.5 0.06

Prod. Temp. 20.7 0.00 24.4 0.00 10.5 0.00

Agg. Size × Prod. Temp. 0.6 0.54 2.8 0.10 0.4 0.71

74

Effect of Foaming Wtr. Cont.

0

0.05

0.1

0.15

0.2

0.25

0.3

12.5 mm NMAS

Limestone

PG 70-22

19.0 mm NMAS

Limestone

PG 70-22

19.0 mm NMAS

Limestone

PG 64-28

12.5 mm NMAS

Crushed Gravel

PG 70-22

Ru

t D

epth

(in

ch)

HMA

WMA 1.8% Foaming w(%)



0

50

100

150

200

250

300

350

12.5 mm NMAS

Limestone

PG 70-22

19.0 mm NMAS

Limestone

PG 70-22

19.0 mm NMAS

Limestone

PG 64-28

12.5 mm NMAS

Gravel

PG 70-22

Dry

IT

S (

psi

)

HMA




0

50

100

150

200

250

300

350

12.5 mm NMAS

Limestone

PG 70-22

19.0 mm NMAS

Limestone

PG 70-22

19.0 mm NMAS

Limestone

PG 64-28

12.5 mm NMAS

Gravel

PG 70-22

Wet

IT

S (

psi

)

HMA




0%

20%

40%

60%

80%

100%

12.5 mm NMAS

Limestone

PG 70-22

19.0 mm NMAS

Limestone

PG 70-22

19.0 mm NMAS

Limestone

PG 64-28

12.5 mm NMAS

Gravel

PG 70-22

TS

R (

%)

HMA WMA 1.8% Foaming w(%)

WMA 2.2% Foaming w(%) WMA 2.6% Foaming w(%)

(a) (b)

(c) (d)

75


Performance Test




&


Binder Type 138.5 0.00 43.0 0.00 42.9 0.00

Foaming Wtr. Cont. 5.4 0.02 1.2 0.29 4.3 0.06



&


Agg. Type 16.6 0.00 7.4 0.03 1.9 0.19

Foaming Wtr. Cont. 4.7 0.03 0.5 0.50 0.6 0.47



&


Agg. Size 1.8 0.20 3.7 0.08 6.0 0.03

Foaming Wtr. Cont. 14.2 0.00 3.0 0.11 0.5 0.48


76

Effect of Agg. Moist. Cont.

0

0.05

0.1

0.15

0.2

0.25

0.3

12.5 mm NMAS

Limestone

PG 70-22

19.0 mm NMAS

Limestone

PG 70-22

19.0 mm NMAS

Limestone

PG 64-28

12.5 mm NMAS

Crushed Gravel

PG 70-22

Ru

t D

epth

(in

ch)

HMA

WMA 0% Aggregate w(%)

WMA 1.5% Aggregate w(%)


0

50

100

150

200

250

300

350

12.5 mm NMAS

Limestone

PG 70-22

19.0 mm NMAS

Limestone

PG 70-22

19.0 mm NMAS

Limestone

PG 64-28

12.5 mm NMAS

Gravel

PG 70-22

Dry

IT

S (

psi

)

HMA




0

50

100

150

200

250

300

350

12.5 mm NMAS

Limestone

PG 70-22

19.0 mm NMAS

Limestone

PG 70-22

19.0 mm NMAS

Limestone

PG 64-28

12.5 mm NMAS

Gravel

PG 70-22

Wet

IT

S (

psi

)

HMA




0%

20%

40%

60%

80%

100%

12.5 mm NMAS

Limestone

PG 70-22

19.0 mm NMAS

Limestone

PG 70-22

19.0 mm NMAS

Limestone

PG 64-28

12.5 mm NMAS

Gravel

PG 70-22

TS

R (

%)

HMA WMA 0% Aggregate w(%)

WMA 1.5% Aggregate w(%) WMA 3.0% Aggregate w(%)

(a) (b)

(c) (d)

77


Performance Test




&


Binder Type 67.5 0.00 331.8 0.00 58.5 0.00

Agg. Moist. Cont. 0.1 0.94 25.0 0.00 5.4 0.02



&


Agg. Type 0.0 0.96 0.1 0.74 8.6 0.01

Agg. Moist. Cont. 2.7 0.11 6.8 0.01 6.9 0.01



&


Agg. Size 3.3 0.09 4.2 0.06 9.3 0.01

Agg. Moist. Cont. 15.0 0.00 1.6 0.24 2.6 0.12


Conclusions

78

79


Reducing the production temperature of foamed WMA

resulted in increased susceptibility to permanent

deformation (or rutting) and moisture-induced damage.

Therefore, it is recommended that a maximum reduction

temperature of 30oF (16.7oC) be specified for the

production of foamed WMA.

80


Increasing the foaming water content (up to 2.6% of the

weight of the asphalt binder) during production of

foamed WMA did not seem to have a negative effect on

the rutting performance or moisture sensitivity of foamed

WMA.

Therefore, a higher foaming water content can be

specified for the production of foamed WMA in Ohio.

81


Producing foamed WMA using moist aggregates

resulted in inadequate aggregate coating leading to

concerns with regard to moisture-induced damage and

long-term durability.

Therefore, it is critical to use fully dried aggregates in the

production of foamed WMA to ensure satisfactory mix

performance. Given that foamed WMA is typically

produced using lower production temperatures than

conventional HMA, the aggregates may need to be

dried for a longer period of time.

Part 4:

Performance of Foamed WMA

and HMA in the APLF

82

83

Field Performance of WMA vs. HMA

Testing Location: Accelerated Pavement

Loading Facility (APLF) at Ohio University (OU)

in Lancaster, OH

Material Combinations:

HMA Superpave 19.0 mm (Intermediate)

WMA Superpave 19.0 mm (Intermediate)

HMA Superpave 12.5 mm (Surface)

WMA Superpave 12.5 mm (Surface)

Asphalt Contractor: The Shelly Company

HMA

3” 19 mm 64-28

WMA

3” 19 mm 64-28

HMA

1.5” 12.5 mm 70-22

1.5” 12.5 mm 70-22

WMA

1.5” 12.5 mm 70-22

1.5” 12.5 mm 70-22

1

4 3 2

45 ft

22.5 ft

22.5 ft

8 ft 8 ft 8 ft

Loading

Direction

84

APLF Testing

85

APLF Testing

1 ¼ inch Surface Course

3 inch Intermediate Course

7 ¾ inch AC Base Course

4 inch Fatigue Resistant AC Layer

6 inch Dense Graded Aggregate Base

Silty Clay Subgrade

Mill and Pave

Top 3 inches

86

APLF Testing

87

APLF Testing

88

APLF Testing

89

APLF Testing

90

APLF Testing

91

APLF Testing

92

APLF Testing

93

APLF Testing

94

APLF Testing

95

APLF Testing

96

APLF Testing

97

APLF Testing

98

APLF Testing

99

APLF Testing

100

APLF Testing

101

APLF Testing

Test conditions and procedure:

Testing Temperature: 104oF

Load Level: 9000 lbs

Wheel Speed: 5 mph

No. of Passes: 10,000

Rutting measurement: lane profiler (two locations per

section)

102

APLF Testing

103

APLF Testing

104

Rutting (19 mm – Intermediate HMA)

4

4.1

4.2

4.3

4.4

4.5

4.6

4.7

4.8

4.9

5

0 20 40 60 80 100 120

Su

rfa

ce E

leva

tion

(in

ch)

Transverse Distance (inch)

0

300

1,000

3,000

10,000

105

Field Testing Plan

Rutting Performance

Laboratory

APA Test

Laboratory-Produced

Laboratory-Compacted

Plant-Produced

Laboratory-Compacted

Plant-Produced

Field-Compacted (Cores)

APLF

Rolling Wheel Test

Plant-Produced

Field-Compacted (Sections)

106

Field and Laboratory Results

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

HMA 12.5 mm LS &

PG 70-22M

Foamed WMA 12.5

mm LS & PG 70-22M

HMA 19.0 mm LS &

PG 64-28

Foamed WMA 19.0

mm LS & PG 64-28

Rut

Dep

th (

inch

)

Laboratory-Produced Laboratory-Compacted

Plant-Produced Laboratory-Compacted

Plant-Produced Field-Compacted (Field Cores)

Plant-Produced Field-Compacted (APLF Sections)

HMA

12.5 mm NMAS

Limestone

PG 70-22

Foamed WMA

12.5 mm NMAS

Limestone

PG 70-22

HMA

19.0 mm NMAS

Limestone

PG 64-28

Foamed WMA

19.0 mm NMAS

Limestone

PG 64-28

107

Field and Laboratory Results

Effect F-value Prob.

Preparation Method 45.92 <.0001

Mix Type 0.77 0.3874

Preparation Method × Mix Type 1.31 0.2853

Method Estimate Standard Error Ranking

Laboratory-Produced Laboratory-Compacted 0.1275 0.008440 A

Plant-Produced Laboratory-Compacted 0.1324 0.008440 A

Plant-Produced Field-Compacted (Field Cores) 0.2512 0.008440 B

Multi-Factor ANOVA Results for APA Rut Depths.

Results of Post ANOVA analyses on APA Rutting Values.

Conclusions

108

109

Conclusions

The APLF and APA rut depth values obtained

for the foamed WMA and HMA mixtures were

comparable for both surface and intermediate

mixtures.

This suggests that the foamed WMA mixtures

have similar rutting resistance to the HMA

mixtures.

110

Conclusions

The plant-produced laboratory-compacted and

laboratory-produced laboratory-compacted

specimens had comparable APA rut depth

values for both foamed WMA and HMA

mixtures.

This indicates that the laboratory mix

preparation procedure used in this study

resulted in comparable foamed WMA and HMA

mixtures to those produced in the field.

Recommendations for

Implementation

111

112


Reducing the production temperature of foamed

WMA led to increased susceptibility to

permanent deformation (rutting) and moisture-

induced damage. Therefore, it is recommended

to continue to use a reduction temperature of

30oF (16.7oC) for the production of foamed

WMA.

113


Increasing the foaming water content (up to

2.6% of the weight of the asphalt binder) during

production of foamed WMA did not seem to

have a negative effect on the rutting

performance or moisture sensitivity of foamed

WMA. Therefore, a higher foaming water

content can be specified for the production of

foamed WMA in Ohio.

114


Producing foamed WMA using moist

aggregates resulted in inadequate aggregate

coating leading to concerns with regard to

moisture-induced damage and long-term

durability. Therefore, it is critical to use fully

dried aggregates in the production of foamed

WMA to ensure satisfactory mix performance.

115


There is no need to compact the foamed WMA

mixtures to a higher density level that

commonly used for HMA mixtures.

Since the performance of the foamed WMA

was comparable to that of the HMA, no

modifications are needed to the current mix

design process used by ODOT for foamed

WMA mixtures.

116

Questions?