TRANSPORTATION RESEARCH BOARD. Long-term Field Performance of WMA Pavements. Wednesday, October 25, :00-2:30PM ET

Transcription

1 TRANSPORTATION RESEARCH BOARD Long-term Field Performance of WMA Pavements Wednesday, October 25, :00-2:30PM ET

2 The Transportation Research Board has met the standards and requirements of the Registered Continuing Education Providers Program. Credit earned on completion of this program will be reported to RCEP. A certificate of completion will be issued to participants that have registered and attended the entire session. As such, it does not include content that may be deemed or construed to be an approval or endorsement by RCEP.

3 Purpose Discuss NCHRP Research Report 843. Learning Objectives At the end of this webinar, you will be able to: Compare field performance of WMA with control HMA pavements in transverse cracking, longitudinal cracking, rutting, and moisture susceptibility Identify significant material property determinants that have both engineering and statistical impacts on the long-term field performance of HMA and WMA pavements Identify laboratory tests that can be integrated into mix design and evaluation to improve the long term performance of asphalt pavements Describe the critical roles of other facts, such as pavement structure and climate, on long term performance of asphalt pavements

4 NCHRP Research Report 843: Long-Term Field Performance of Warm Mix Asphalt Technologies NCHRP Project 09-49A

5 NCHRP is a State-Driven Program Sponsored by individual state DOTs who Suggest research of national interest Serve on oversight panels that guide the research. Administered by TRB in cooperation with the Federal Highway Administration.

6 Practical, ready-to-use results Applied research aimed at state DOT practitioners Often become AASHTO standards, specifications, guides, syntheses Can be applied in planning, design, construction, operations, maintenance, safety, environment

7 Today s Speakers Shihui Shen, Pennsylvania State University Shenghua Wu, University of South Alabama Weiguang Zhang, Southeast University, China

8 TRB Webinar Long-Term Field Performance of Warm Mix Asphalt Pavements NCHRP 9-49A Project Research Team Washington State University Pennsylvania State University Louisiana State University, Louisiana Transportation Research Institute October 25, 2017

9 Long-term Field Performance Comparison between HMA and WMA Shihui Shen Ph.D., Associate Professor Department of Engineering Pennsylvania State University, Altoona Phone: (814)

10 Outline Introduction & Objectives Project Scope and Research Approach Results of Field Performances Volumetrics Transverse Cracking Wheel-path Longitudinal Cracking Rutting & Moisture Susceptibility 2

11 Introduction Rapid growth in the use of WMA Limited research on long-term performance of WMA How WMA compares with HMA in terms of specific performance What are the critical material properties that could have significant impact on the long-term performance of WMA Better understanding of WMA technologies for full implementation Long-term Performance 3

12 Research Objectives Investigate the long-term field performance of WMA: - Transverse cracking - Wheel-path longitudinal cracking - Rutting and moisture damage Identify the material and engineering properties of WMA pavements that are significant determinants of their longterm field performance 4

13 Outline Introduction & Objectives Project Scope & Research Approach Results Volumetrics Transverse Cracking Wheel-path Longitudinal Cracking Rutting & Moisture Susceptibility 5

14 Project Scope 28 pavement projects o 22 in-service projects +1 HVS = 40 HMA-WMA pairs 4-9 years pavement age o 5 newly constructed in 2011/2012 = 8 HMA-WMA pairs Climate Zone In-serv. New Total D/F D/N F W/F W/N F

15 Scope: Project Distribution No. of Projects WMA Type Organic Chemical Foaming Dry Freeze Wet Freeze Dry No-Freeze Wet No-Freeze Climate Zone No. of Projects Pavement Age Pavement Type No. of Projects No. of Projects (4,5) (5,7) (7, 9) 0 Flexible PCC or Cement Stabilized Base

16 Scope: Project Distribution Traffic (ESALs) Use of Anti-stripping No. of Projects < 3 million > = 3 million No. of Projects Yes No N/A Use of RAP No. of Projects Yes No N/A

17 Research Approach Selection of WMA Candidate Projects Field Characterization (Field cores, plant mix) Distress Survey: Transverse and longitudinal cracking, rutting FWD test Laboratory Characterization (cores, recovered binders) Volumetrics: aggregate gradation, AC, Gmm, Gmb Material properties: binder PG, MSCR, IDT, Hamburg, etc. 9

18 Mixture Test Testing Conditions Material Properties References /Standards Material Characterization: Mixture IDT Dynamic Modulus/Creep Compliance Temp.: 4, 14, 32, 50, 68, 86ºF; Frequency: 20, 10, 5, 1, 0.1, 0.01 Hz Duration: 100 seconds Dynamic modulus; Creep compliance Fatigue- IDT Fracture at Room Temp Temp.: 68ºF Loading rate: 2 in./min IDT strength; Fracture work density; Vertical failure deformation Horizontal failure strain Thermal Cracking- IDT Fracture at Low Temp Temp.: 14ºF Loading rate: 0.1 in./min IDT strength; Fracture work density; Vertical failure deformation; Horizontal failure strain Rutting /Moisture Hamburg Temp.: 122ºF Wet condition Rut depth; Stripping inflection point (SIP); Cycles Wen et al AASHTO T322 Wen 2012 AASHTO T324 Volumetric property check: Gradation AC content Gmm and Gmb Air voids VMA, VFA Film thickness 10

19 Material Characterization: Asphalt Binder Binder Test Testing Conditions Material Properties References/Stan dards PGs Different temp depending on the test (DSR, BBR) PG; BBR stiffness; m-value AASHTO MP1/T240/T313 Rutting: MSCR Stress: 0.1, 3.2kPa Temp.: 98% Reliability from LTPP Bind Jnr 0.1, Jnr 3.2 ; R 0.1, R 3.2 Fatigue: Monotonic at Room Temp Temp.: 68ºF Shear strain rate: 0.3 s -1 Maximum stress; Fracture energy; Failure strain Thermal Cracking: Monotonic at Low Temp Temp.: 41ºF Shear strain rate: 0.01s -1 Maximum stress; Fracture energy; Failure strain AASHTO T350 Wen et al Wen

20 Research Approach Field Test Results Lab Test Results 12

21 Field Characterization: Two-Rounds of Distress Survey Transverse Cracking Reflective Surface-initiated 13

22 Field Characterization: Two-Rounds of Distress Survey Wheel-path Longitudinal Cracking Observation: 2 to 4 feet away from the shoulder or centerline. Field cores indicate top-down fatigue cracks. 14

23 Field Characterization: Two-Rounds of Distress Survey Rut Depth 15

24 Other Data Collection Activities Pre-construction o mix design, existing pavement structure, location, existing pavement distress, etc. Construction information o plant modification, mix/compaction temp., inplace density, raw materials. Post-construction o QA/QC data, procurement of cores, FWD, etc. 16

25 Outline Introduction & Objectives Project Scope and Research Approach Results Volumetrics Transverse Cracking Wheel-path Longitudinal Cracking Rutting & Moisture Susceptibility 17

26 In-place Volumetric Properties HMA vs. WMA Asphalt content: almost identical Air voids of field cores: WMA > HMA 18

27 Outline Introduction & Objectives Project Scope and Research Approach Results Volumetrics Transverse Cracking Wheel-path Longitudinal Cracking Rutting & Moisture Susceptibility 19

28 Field Transverse Cracking HMA vs. WMA, 2014/2015 (4-9 years) 20

29 Field Transverse Cracking HMA vs. WMA, Y2014/2015 (4-9 years) No. of Pairs H > W H = W H < W 21

30 Effect of Aging on Transverse Cracking 22

31 Outline Introduction & Objectives Project Scope and Research Approach Results Volumetrics Transverse Cracking Wheel-path Longitudinal Cracking Rutting & Moisture Susceptibility 23

32 Field Wheel-path Longitudinal Cracking Y2013/2015 (4-9 years) 24

33 Field Wheel-path Longitudinal Cracking HMA vs. WMA, Y2014/2015 (4-9 years) H > W H = W H < W 25

34 Wheel-path Longitudinal Cracking Effect of Pavement Age Wheel-path Longitudinal Crack Length, ft/200ft HMA WMA Pavement Age, years 26

35 Outline Introduction & Objectives Project Scope and Research Aproach Results Volumetrics Transverse Cracking Wheel-path Longitudinal Cracking Rutting & Moisture Susceptibility 27

36 Field Rutting Performance Y2014/2015 (4-9 years) 28

37 Field Rutting Performance HMA vs. WMA, Y2014/2015 (4-9 years) 1/16, as a practical criterion to determine if any significant difference between the HMA and WMA pavements. No. of Pairs H > W H = W H < W 29

38 Field Rut Depth Effect of Pavement Age Second-Round Rut Depth, in TN SR 125 WA SR 12 HMA WMA Pavement Age, years 30

39 Moisture Susceptibility Moisture damage was not observed Both WMA and HMA pavements Consistent with NCHRP 9-49 findings Use SIP to evaluate field cores 31

40 Moisture Susceptibility Lab Hamburg Wheel Track Test Results Projects Red : No anti-strip agent Black : W/ anti-strip agent Green : Info not available 32

41 Relationship between Rutting and Cracking Performance Dry Freeze Climatic Zone Rutting Dominates 33

42 Relationship between Rutting and Cracking Performance Dry Non-Freeze Climatic Zone Not Conclusive 34

43 Relationship between Rutting and Cracking Performance Wet Freeze Climatic Zone Cracking Dominates 35

44 Relationship between Rutting and Cracking Performance Wet Non-freeze Climatic Zone Cracking & Rutting 36

45 Significant Determinants of Longterm Field Performance Shenghua Wu Ph.D., Assistant Professor Dept. of Civil, Coastal, and Environmental Engineering University of South Alabama, Mobile, AL Phone: (251)

46 Objectives Identify the material and engineering properties of WMA pavements that are significant determinants of their longterm field performance - Paired ranking method - Statistical Partial Least Square (PLS) Method - Binary Logistic (BL) Regression 38

47 Methodology: Statistics Based Methods Paired Ranking o Ranking of variables and field performance; o Comparison between variable and performance ranking, find significant determinants. Partial Least Square (PLS) o Solve collinearity issue; o Works well for small sample size; o Crack propagation model, significant determinants. Binary Logistic (BL) o Probabilistic-based; o Analyzing data with two categorical responses; o Crack initiation model, significant determinants. 39

48 Significant Determinants for Transverse Crack: Potential Variables Considered Material Climate Structure Traffic Predictor Variables Unit Range IDT strength, 14 F Mpa Creep compliance (D 1 ), -4 F 1/Gpa Creep compliance (D 2 ), 14 F 1/Gpa Creep compliance (D 3 ), 32 F 1/Gpa m-value, creep compliance N/A Fracture work density, 14 F Mpa Air voids % Binder low PG C -6.5 to Binder stiffness, BBR Pa m-value, BBR, -6 C N/A Asphalt content % Effective binder content % Percent Passing # 4 Sieve % Percent Passing # 8 Sieve % Percentage Passing #200 sieve % NMAS mm Pavement age year 2-7 Low temperature hour hour HMA thickness inch Overlay thickness inch AADTT N/A

49 Significant Determinants for Transverse Cracking (Based on 2 nd Round Results) No. of Pairs Mix E* (14 F) Mix work density (14 F) BBR m-value (10.4 F) 10 5 Mix horizontal failure strain (68 F) 0 Positive Negative 41

50 Transverse Crack Propagation Model Y = e X X X X X X 6 Y = transverse crack length, ft/200 ft; e = base of natural logarithm; X 1 = fracture work density (14 F), Mpa; X 2 = creep compliance (32 F), 1/GPa; X 3 = average yearly low-temperature hour, hr (from AASHTOWare Pavement ME Design); X 4 = percentage passing No. 200 sieve, %; X 5 = overlay thickness, in.; X 6 = AADTT. (a) Predicted vs. Measured (b) Model Validation 42

51 Transverse Crack Initiation Model PP yy ii = 1 = 1 1+ee X X8+1.52X X10 where PP = probability of initiation of transverse crack, %; y i = ith pavement section; e = base of natural logarithm; X 7 = average yearly low-temperature hour, hr (from AASHTOWare Pavement ME Design); X 8 = percentage passing No. 200 sieve, %; X 9 = IDT strength (14 F), MPa; and X 10 = pavement age, year. (a) Predicted vs. Measured (b) Model Validation 43

52 Significant Determinants for Transverse Cracking 1 st Round Ranking Mix Fracture Work Density, 14 F, (-) Mix E*, 14 F, (+) Mix IDT Strength, 68 F, (+) Binder BBR Stiffness, 14 F, (+) Mix Vertical Failure Deformation, 68 F, (-) Mix Horizontal Failure Strain, 68 F, (-) 2 nd Round Ranking Mix Fracture Work Density, 14 F, (-) Mix E*, 14 F, (+) Binder BBR m-value, 14 F, (-) Mix Vertical Failure Deformation, 68 F, (-) Statistical PLS Model, Crack Propagation Creep Compliance, 32 F, (-) Average Yearly Low-temperature Hour, (+) AADTT, (+) Overlay Thickness, in., (-) Percentage Passing No. 200 Sieve, %, (-) Mix Fracture Work Density, 14 F, (-) Statistical PLS Model, Crack Initiation Pavement Age, (+) IDT Strength, 14 F, (+) Average Yearly Low-temperature Hour, (+) Percentage Passing No. 200 Sieve, (-) 44

53 Significant Determinants for Longitudinal Cracking: Potential Variables Considered Material Structure Traffic Predictor Variables Unit Range IDT strength, 68 F MPa Work density, 68 F MPa Dynamic Modulus, 70 F, 1Hz MPa Mixture Fracture Energy, 68 C MPa Air Voids % Percent Passing # 4 Sieve % Percent Passing # 8 Sieve % Percent Passing #200 Sieve % NMAS mm G*sin(phase angle) kpa Binder Fracture Energy MPa Effective Binder Content % Total Pavement Thickness mm Overlay Thickness mm AADTT N/A Pavement age year

54 Significant Determinants for Longitudinal Cracking (Based on 2 nd Round Results) 24 No. of Pairs Mix IDT strength(68 F) Mix creep compliance (68 F) Mix horizontal failure strain (68 F) Mix vertical failure deformation (68 F) 0 Positive Negative 46

55 Longitudinal Crack Propagation Model Y = ee ( XX XX XX XX XX 5 ) where Y = field longitudinal crack, ft/200 ft; e = base of natural logarithm; X 1 = total pavement thickness, mm; X 2 = IDT strength (68 o F), MPa; X 3 = in-place air voids, %; X 4 = AADTT; and X 5 = percentage passing No. 200 sieve, %. (a) Predicted vs. Measured (b) Model Validation 47

56 Longitudinal Crack Initiation Model PP yy ii = 11 = where ee ( XX XX XX XX XX10) P = probability of initiation of top-down crack, %; X 6 = pavement age, year; X 7 = percentage passing No. 200 sieve, %; X 8 = overlay thickness, mm; X 9 = fracture work density (68 F), MPa; X 10 = binder fracture energy (68 F), MPa; and y i = i th pavement section. (a) Predicted vs. Measured (b) Model Validation 48

57 Significant Determinants for Longitudinal Cracking 1 st Round Ranking Mix Horizontal Failure Strain, 68 F, (-) Mix Vertical Failure Deformation, 68 F, (-) Mix IDT Strength, 68 F, (+) Mix Creep Compliance, 14 F, (-) 2 nd Round Ranking Mix Horizontal Failure Strain, 68 F, (-) Mix Vertical Failure Deformation, 68 F, (-) Mix IDT Strength, 68 F, (+) Mix Creep Compliance, 14 F, (-) Statistical PLS Model, Crack Propagation Total Pavement Thickness, (+) Percentage Passing No. 200 Sieve, (-) In-place Air Voids, (+) Mix IDT Strength, 68 F, (+) AADTT, (+) Statistical PLS Model, Crack Initiation Pavement Age, (+) Binder Fracture Energy, 68 F, (+) Overlay Thickness, (-) Mix Fracture Work Density, 68 F, (-) Percentage Passing No. 200 Sieve, (-) 49

58 Material Climate Structure Traffic Significant Determinants for Rut Depth: Potential Variables Considered Variable Unit Range RRI NA In-place air voids % Asphalt film thickness μm Effective binder content % High temperature performance grade (PG) C MSCR J nr0.1 kpa MSCR J nr3.2 kpa MSCR J nrdiff % MSCR R 0.1 % MSCR R 3.2 % Mixture dynamic modulus, 30 C, 0.1Hz MPa Percent Passing # 4 Sieve % Percent Passing # 8 Sieve % Percentage Passing # 200 sieve % NMAS mm Pavement age month AADTT NA Overlay thickness mm Total HMA thickness mm Mixing temperature C Accumulated hour of air temperature>25 C hour

59 Significant Determinants for Rut Depth (Based on 2 nd Round Results) Jnr0.1 No. of Pairs Jnr3.2 Hamburg Rutting Resistance Index Binder high temp PG 5 0 Positive Negative Mix E* (86 F) 51

60 Rutting Resistance Index (RRI) Hamburg Wheel-Tracking Test AASHTO T324 (50 C) RRI = N (1 - RD) N = number of passes at completion of test RD = rut depth at completion of test, inch. RRI

61 Rut Depth Predictive Model Y = ln X ln (X 2 ) ln (X 3 ) ln (X 4 ) ln (X 5 ) Where, Y = field-measured rut depth, inch; X 1 = pavement age, month; X 2 = RRI; X 3 = AADTT; X 4 = total HMA thickness, mm; and X 5 = overlay thickness, mm. (a) Predicted vs. Measured (b) Model Validation 53

62 Significant Determinants for Rut Depth 2 nd Round Ranking Mix Rutting Resistance Index, (-) Binder High PG, (-) J nr0.1, J nr3.2, (+) Mix E*, (-) Mix Creep Compliance, (+) Statistical Model Mix Rutting Resistance Index, (-) Pavement Age, (+) AADTT, (+) Total HMA Thickness, (+) Overlay HMA Thickness, (+) 54

63 Summary and Findings Weiguang Zhang Ph.D., Associate Professor School of Transportation Southeast University, Nanjing, China Phone: (86)

64 Findings: Transverse Cracking Transverse cracks were found to initiate from the top surface of the pavement, but often overlapped with transverse cracks in existing asphalt layer Transverse cracking could be a combination of thermal and reflective cracking. Transverse cracking performance between HMA and WMA Comparable for the majority of HMA and WMA pavements Mostly seen in pavements with four or more years of age 56

65 Findings: Transverse Cracking Mixture s fracture work density obtained from IDT testing at 14 F is recommended as a significant determinant; The Higher fracture work density, the less transverse cracking. Other indicators: mix E* (14 F), mix IDT strength (68 F), mix creep compliance (32 F) and mix vertical failure deformation (68 F) values. 57

66 Findings: Wheel-path Longitudinal Cracking Cracks were found to initiate from surface of pavement May be indicative of top-down fatigue cracking. Performance comparison between HMA and WMA Comparable for the majority of HMA and WMA pavements Cracks start to develop mostly at age of 4 years; more cracking is seen with 6+ years. 58

67 Findings: Wheel-path Longitudinal Cracking The mixture s IDT strength at 68 F is recommended as the significant determinant. The relatively lower IDT strength, the less longitudinal cracking. Other indicators: the mix vertical failure deformation (68 F) and horizontal failure strain (68 F) from IDT test, and mix creep compliance (14 F) values. 59

68 Findings: Rutting & Moisture Susceptibility Rutting performance between HMA and WMA pavements is mainly comparable. Field rut depth starts to build up as early as 3 years; and becomes more differentiable (more than 0.1 ) with 6 or more years service. Based on field investigation, no moisture-related distress was found in both HMA and WMA pavements. Based on laboratory HWT test results, most of mixes without an anti-stripping agent exhibited SIPs The use of anti-stripping agent may be beneficial overall for both HMA and WMA mixtures. 60

69 Findings: Rutting & Moisture Susceptibility RRI value from Hamburg wheel tracking test is recommended as significant determinant for rutting performance. Higher RRI, lower rut depth in the field. Other indicators: mix E* (86 F), mix creep compliance (86 F), binder PG, and percent recovery. 61

70 Reduced production temperature of WMA can have an influence on field density. The in-place density of WMA is generally lower than HMA pavements Distress distribution appears to be climatic related. Within dry zones (freeze or non-freeze), rutting appears to be the major type of distress, regardless of HMA or WMA Within wet freeze zones, cracking is the dominant distress type Within wet non-freeze zones, cracking and rutting can both happen. U Findings: Overall Effect of moisture on cracking!!. 62

71 Acknowledgements NCHRP 9-49A project Dr. Ed Harrigan and panel members Field work partners, Braun Intertec. Inc & Bloom Companies, LLC Statisticians from PSU and WSU FHWA mobile lab, State DOTs and local agencies Past NCHRP WMA project teams, universities, graduate students, 63

72 Thank You! Any questions? 64

73 Today s Participants Ed Harrigan, Transportation Research Board, eharriga@nas.edu Shihui Shen, Pennsylvania State University, szs20@psu.edu Shengua Wu, University of South Alabama, shenghuawu@southalabama.edu Weiguang Zhang, Southeast University, China, wgzhang@seu.edu.cn

74 Get Involved with TRB Getting involved is free! Join a Standing Committee ( Become a Friend of a Committee ( Networking opportunities May provide a path to become a Standing Committee member For more information: Create your account Update your profile 97 th TRB Annual Meeting: January 7-11, 2018

75 Get involved with NCHRP Suggest NCHRP research topics Volunteer to serve on NCHRP panels Lead pilot projects and other implementation efforts at your agency For more information:

76 Take Part in the Careers in Motion Networking Fair