NCHRP 9-47A Update October 13, 2010

Transcription

1 NCHRP 9-47A Update October 13, 2010

2 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 3

4 NCHRP 9-47A Sites Dry Freeze Wet Freeze Dry No Freeze Wet No Freeze 4

5 9-47A Projects Location WMA Technologies Date Constructed St. Louis, MO, Hall Street Evotherm ET, Sasobit, Aspha-min Sep-2006 Iron Mountain, MI, M95 Sasobit Sep-2006 Silverthorne, CO, I-70 Advera, Sasobit, and Evotherm DAT Aug-2007 Franklin, TN, SR45 Astec DBG, Advera, Evotherm DAT, & Sasobit Oct-2007 Graham, TX Astec DBG Jun-2008 George, WA, I-90 Sasobit Jun-2008 Walla Walla, WA Maxam Aquablack Apr-2010 Centerville, VA, I-66 Astec DBG Jun-2010 Escanaba MI Evotherm 3G, and Advera Jun-2010 Baker, MT Evotherm DAT Aug-2010 Griffith, IN Evotherm, Gencor foam, & Heritage wax Sep-2010 Jefferson Co., FL, SR 30 Terex foaming system Oct-2010 NYC, NY, Little Neck Pkwy Cecabase, Sonneborn, & Hydorgreen Oct

6 Engineering Properties Plant mix samples Dynamic Modulus Flow Number S-VECD (push-pull) fatigue IDT Creep Compliance & Strength Hamburg WTD Tensile Strength Ratio Other tests Mix moisture contents Volumetric properties Infrared Temperature Bar In-place density Recovered binder properties 6

7 Construction Documentation Production Energy Audit & Stack Emissions Measured at three multi-technology sites HMA production run of same mix for comparison Bob Frank is coordinating testing and conducting analyses 7

8 Construction Documentation Industrial Hygiene 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 8

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 9 HMA WMA Reflective Bumps

10 Iron Mountain, MI Technologies: Sasobit & control HMA Date Constructed: September, 2006 Climate: Wet, Freeze Roadway description: rural highway with logging traffic 10

11 Iron Mountain, MI 2 yrs: Less than 3 mm of Rutting for Sasobit and HMA No cracking in WMA or HMA 11

12 Iron Mountain, MI Mix Tensile Strength of Cores at 2 years Location Air Voids (%) Tensile Strength (psi) Sasobit Wheelpath HMA Wheelpath Sasobit Between Wheel Paths HMA Between Wheel Paths

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. 13

14 Silverthorne, CO 3 years Less cracking in WMA sections compared to control HMA Rutting and raveling are comparable 14

15 Franklin, Tennessee WMA Technologies: Evotherm DAT, Advera, Sasobit, Astec Double Barrel Green, and control HMA Date Constructed: Oct Climate: Wet, No Freeze Roadway description: country road 15

16 Franklin, Tennessee Performance: No rutting A little raveling Small spots of asphalt in control and Advera sections 16

17 Graham, TX WMA Technology: Astec DBG Date Constructed: June 2008 Climate: Dry, No Freeze Roadway description: Performance: no distresses 17

18 NCAT Test Track Performance: No rutting No cracking No raveling >11.5 MESALs 18

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 19

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 20

21 Tensile Strength Ratio Tensile Strength Ratio HMA WMA Compaction Temperature (F) 21

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 22

23 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 Hamburg Testing 23

24 Hamburg Analysis Deformation (mm) Rutting Rate Cycles Stripping Inflection Point 24

25 Hamburg : Stripping Inflection Point Stripping Inflection Point (cycles) HMA WMA Compaction Temperature (F) 25

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 26

27 AASHTO TP 63 6 cylindrical specimens Specimens compacted to 7 1% air voids Tested at high PG Air chamber Rut depth (manual and automated) APA 27

28 APA Rut Depths Rut Depth (mm) HMA WMA Compaction Temperature (F) 28

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 29

30 Recovered High PG HMA WMA 80 High True Grade (C) Mixing Temperature (F) 30

31 Recovered Low PG Low True Grade (C) HMA WMA -35 Mixing Temperature (F) 31

32 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

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35 Lab Testing 35 35

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 36

37 Strain Instrumentation and Wireless Data Acquisition Right Gauge Longtidinal Microstrain Time, sec

38 N8 and N9 Strain vs. Temperature Tensile Microstrain N8 Strain = e *Temperature R 2 = 0.96 N9 Strain = e *Temperature R 2 = N8 N Mid-Depth Temperature, F 38

39 The NCAT Test Track The 4 th Cycle

40 2009 Group Experiment

41 Group Experiment Warm Mix (S10 & S11) Foamed WMA Section Control HMA Section Additive WMA Section

42 Group Experiment High RAP (N10 & N11) Control HMA Section 50% RAP Section 50% RAP WMA Section

43

44 Thank You