NCHRP 9-47A UpdateOctober 13, 2010

Overview

• Acknowledgements

• Research Objectives

• Performance of Select WMA Field Projects

• Lab Results that cause concerns with WMA

• NCAT Test Track WMA sections

3

NCHRP 9-47A Project Objectives Establish relationships between engineering properties

of WMA to field performance

Compare WMA to HMA

Performance

Construction practices

Emissions and fuel usage

Cost

4

NCHRP 9-47A Sites

Dry Freeze

Wet Freeze

Wet No FreezeDry No Freeze

5

9-47A ProjectsLocation WMA Technologies Date

ConstructedSt. Louis, MO, Hall Street Evotherm ET, Sasobit, Aspha-min Sep-2006Iron Mountain, MI, M95 Sasobit Sep-2006Silverthorne, CO, I-70 Advera, Sasobit, and Evotherm DAT Aug-2007Franklin, TN, SR45 Astec DBG, Advera, Evotherm DAT, & Sasobit Oct-2007Graham, TX Astec DBG Jun-2008George, WA , I-90 Sasobit Jun-2008Walla Walla, WA Maxam Aquablack Apr-2010Centerville, VA, I-66 Astec DBG Jun-2010Escanaba MI Evotherm 3G, and Advera Jun-2010Baker, MT Evotherm DAT Aug-2010Griffith, IN Evotherm, Gencor foam, & Heritage wax Sep-2010Jefferson Co., FL, SR 30 Terex foaming system Oct-2010NYC, NY, Little Neck Pkwy Cecabase, Sonneborn, & Hydorgreen Oct-2010

6

Engineering PropertiesPlant mix samples Other tests Dynamic Modulus

Flow Number

S-VECD (push-pull) fatigue

IDT Creep Compliance & Strength

Hamburg WTD

Tensile Strength Ratio

Mix moisture contents

Volumetric properties

Infrared Temperature Bar

In-place density

Recovered binder properties

7

Construction Documentation

Measured at three multi-technology sites

HMA production run of same mix for comparison

Bob Frank is coordinating testing and conducting analyses

Production Energy Audit & Stack Emissions

8

Construction Documentation

Heritage Research to conduct IH testing at Indiana and New York City projects

Workspace and respiration monitoring using NIOSH standards:

Operator

Screed person

Raker

Site background blank

Industrial Hygiene

9

St. Louis, MO

WMA Technologies: Evotherm ET, Sasobit, Aspha-min

Date Constructed: May 2006

Climate: Wet, Freeze

Roadway description: industrial traffic

Performance: No bumps in WMA sections, No rutting, Very minor reflection cracking

HMAWMA

ReflectiveBumps

10

Iron Mountain, MI

Technologies: Sasobit & control HMA

Date Constructed: September, 2006

Climate: Wet, Freeze

Roadway description: rural highway with logging traffic

11

Iron Mountain, MI

Performance @ 2 yrs:

Less than 3 mm of Rutting for Sasobit and HMA

No cracking in WMA or HMA

12

Iron Mountain, MI

Mix LocationAir Voids

(%)

TensileStrength

(psi)

Sasobit Wheelpath 5.5 95

HMA Wheelpath 2.8 93

Sasobit Between Wheel Paths 4.1 79

HMA Between Wheel Paths 2.5 81

Tensile Strength of Cores at 2 years

13

Silverthorne, CO

WMA Technologies: Advera, Sasobit, Evotherm DAT, plus HMA control

Date Constructed: July-Aug, 2007

Climate: Dry, Freeze

Roadway description: I-70, uphill grade through Rocky Mtns.

14

Silverthorne, CO

Performance @ 3 years

Less cracking in WMA sections compared to control HMA

Rutting and raveling are comparable

15

Franklin, Tennessee

WMA Technologies: Evotherm DAT, Advera, Sasobit, Astec Double Barrel Green, and control HMA

Date Constructed: Oct. 2007

Climate: Wet, No Freeze

Roadway description: country road

16

Franklin, Tennessee

Performance:

No rutting

A little raveling

Small spots of asphalt in control and Advera sections

17

Graham, TX

WMA Technology: Astec DBG

Date Constructed: June 2008

Climate: Dry, No Freeze

Roadway description:

Performance: no distresses

18

NCAT Test Track

Performance:

No rutting

No cracking

No raveling

>11.5 MESALs

19

NCAT Test Track

Technologies: Evotherm emulsion

Date Constructed: October 2005

Roadway description: Very heavy traffic

Climate: Wet, No Freeze

WMA was stored in silo for 17 hrs due to problems with paving equipment

No issues during WMA production or section construction

20

Summary of U.S. WMA Field Trails Ages: up to 5 years old

Most popular WMA Technologies: Evotherm, Sasobit, and Astec Double Barrel Green

Traffic ranges: low to very heavy

Climates: hot to very cold

Common Issues: Tuning the burner

In-Place Densities: same or better than HMA

Performance: Very good overall

21

Tensile Strength Ratio

0

0.2

0.4

0.6

0.8

1

1.2

200

225

230

230

240

250

250

250

250

265

Compaction Temperature (F)

Tens

ile S

treng

th R

atio HMA

WMA

22

TSR Preliminary Analyses < 240 F: TSR of WMA is significantly different (less) than

HMA > 240 F: TSR of WMA is not significantly different than

HMA

23

Hamburg Testing AASHTO T 324 No additional aging of

plant mix Twin molds 50 C water bath 10,000 cycles or to

failure Stripping inflection

point, rut depth, and rutting rate

24

Hamburg Analysis

0.002.004.006.008.00

10.0012.0014.0016.0018.00

0 2000 4000 6000 8000 10000

Cycles

Defo

rmat

ion

(mm

)

Stripping Inflection

Point

Rutting Rate

25

Hamburg : Stripping Inflection Point

0

2000

4000

6000

8000

10000

12000

225

225

225

225

230

230

230

230

240

245

245

250

250

250

250

250

250

260

260

Compaction Temperature (F)

Strip

ping I

nflec

tion P

oint (

cycle

s)

HMAWMA

26

Hamburg Preliminary Analyses Most WMA mixes meet Hamburg SIP criteria even though

the test was not required for mix approval Differences between WMA and HMA are not statistically

significant Compaction temperature does not have a statistical effect

on Hamburg results

27

APA AASHTO TP 63

6 cylindrical specimens

Specimens compacted to 7 1% air voids

Tested at high PG

Air chamber

Rut depth (manual and automated)

28

APA Rut Depths

0.01.02.03.04.05.06.07.08.0

200

225

230

230

240

245

250

250

250

250

260

Compaction Temperature (F)

Rut D

epth

(mm

)

HMAWMA

29

APA Preliminary Analyses Most WMA met a 5.5 mm rut depth criterion WMA often has a greater rut depth than the HMA

< 240 F: WMA rut depths are significantly different (greater) than HMA rut depths

> 240 F: Rut depths of WMA and HMA are not significantly different

APA is known to be sensitive to binder stiffness

30

Recovered High PG

0

10

20

30

40

50

60

70

80

90

100

250 250 250 250 250 250 265 265 265 275 275 275 275 275 275

Hig

h Tr

ue G

rade

(C)

Mixing Temperature (F)

HMA WMA

31

Recovered Low PG

-35

-30

-25

-20

-15

-10

-5

0250 250 250 250 250 250 265 265 265 275 275 275 275 275 275

Low

Tru

e G

rade

(C)

Mixing Temperature (F)

HMA WMA

Current WMA Research on the NCAT Test Track

• New full-depth sections– MeadWestvaco Evotherm DAT WMA

– Astec Foamed Asphalt WMA

– Control HMA

– 50% RAP+WMA

– Thiopave (Sulfur + WMA additive)

•32

33•33

34•34

35•35

Lab Testing

36

NCAT Test Track Evaluation Accelerated loading to evaluate rutting and fatigue

performance over two years

Instrumented to monitor strains for determining if sections respond differently

Known materials properties, environmental conditions and traffic, and performance to compare to MEPDG predictions

Currently over 5.3 million ESALs – no distresses

Strain Instrumentation and Wireless Data Acquisition

Right Gauge

-300

-200

-100

0

100

200

300

400

500

0.5 0.7 0.9 1.1 1.3 1.5 1.7 1.9 2.1 2.3 2.5

Time, sec

Long

tidin

al M

icro

stra

in

38

N8 and N9 – Strain vs. Temperature

N8 Strain = 21.487e0.0335*Temperature

R2 = 0.96

N9 Strain = 11.496e0.0298*Temperature

R2 = 0.9217

0

200

400

600

800

1000

1200

1400

0 20 40 60 80 100 120 140Mid-Depth Temperature, F

Tens

ile M

icro

stra

in

N8 N9

The NCAT Test Track The 4th Cycle

2009 Group Experiment

Group Experiment – Warm Mix (S10 & S11)

Foamed WMA Section

Control HMA Section

Additive WMA Section

Group Experiment – High RAP (N10 & N11)

Control HMA Section

50% RAP Section

50% RAP WMA Section

www.pavetrack.com

Thank Youwww.NCAT.us