Utilization of Cementitious High Carbon Fly Ash to Stabilize Reclaimed Asphalt Pavement as Base Course

Transcription

1 Utilization of Cementitious High Carbon Fly Ash to Stabilize Reclaimed Asphalt Pavement as Base Course Phase II Update April 16, 2008

2 High Carbon Fly Ash Study Sponsor: U.S. DOE Research Team: University of Wisconsin at Madison and Bloom Companies Partner: Minnesota DOT 2

3 Team DOE Project Manager: Robert Patton PI: Haifang Wen (UW) Team: Tuncer Edil and Craig Benson (UW), and Swapna Danda (Bloom) MnDOT: Maureen Jensen, Ben Worel, Tim Cylne, Roger Olson, Ed Johnson, Bob Edstrom, Leonard Palek, John Siekmeier 3

4 Phases of Study Phase I Laboratory Feasibility Study: Aug Mar Phase II Field Demonstration: Aug Dec

5 Phase II Study Full-scale Test Road: MnROAD Well-controlled Well-instrumented Real life application Live truck 5

6 Phase II Study MnROAD Facility 6

7 Phase II Study Pavement Structures at MnROAD 7

8 Phase II Study Using Riverside 8 Fly Ash from Xcel Energy 14.6% LOI (Carbon) 22% CaO 14% Application Rate 8

9 Phase II Study MPCA considers Riverside 8 Fly Ash a noncompliant materials An agreement was made on June 20, 2007 in which MPCA permitted the use of Riverside 8 MPCA requested continuous monitoring 9

10 Phase II Construction MnDOT let the project on June 8, 2007 Midwest Asphalt won the bid. Construction started on July 23 rd,

11 Recycle Asphalt 11

12 RPM Base Course Placement 12

13 Crushed Aggregate 13

14 High Carbon Fly Ash Placement 14

15 RPM/Fly Ash Mixing 15

16 RPM/Fly Ash Mixing 16

17 Instrumentation Pressure Cell, Strain Gauges, Deformation in Base, Temperature, Moisture (MnDOT) Lysimeters for leaching (UW) 17

18 Instrumentation 18

19 Infrastructure Construction 19

20 Instrumentation Strain Gauge 20

21 Lysimeter 21

22 Plan View of Lysimeter 22

23 Installation of Lysimeter 23

24 Pipe to Tank 24

25 Collecting Tank 25

26 Collecting Tank 26

27 HMA Paving 27

28 Too wet for paving 28

29 Finally.. 29

30 Open to traffic, Nov

31 Field Tests Subgrade: Dynamic Cone Penetrometer (DCP), Lightweight Deflectometer (LWD) Base Course: DCP, LWD, Falling Weight Deflectometer (FWD), Soil Stiffness Gauge (SSG) HMA: FWD 31

32 Dynamic Cone Penetrometer Calculate DCP Penetration Index and Estimate Modulus DPI i Re adingi 5 Re adingi 5 log( E i ) log( DPI i ) 32

33 Soil Stiffness Gauge Automatically read the material modulus 33

34 Lightweight Deflectometer 2P 2 E (1 ). R. a. D o A P=Peak load A=Contact area R=Plate radius =Rigidity factor D 0 =Center Deflection *Dynatest,

35 Falling Weight Deflectometer Backcalculate the modulus of layers 35

36 Modulus from LWD, MPa Field Tests Modulus LWD, 7days DCP, 7days DCP 21days FWD, 21 days SSG, 21days RPM Crushed Aggregate RPM+FA Base Courses Materials 36

37 CBR Lab Tests CBR RPM Crushed Aggregate RPM+14FA, 7d Base Course Materials 37

38 Resilient Modulus, MPa Lab Tests Resilient Modulus RPM Crushed Aggregate RPM+14FA, 7d Base Course Materials 38

39 Permanent Deformation, mm Lab Tests Permanent Strain after Mr Tests RPM Crushed Aggregate RPM+14FA, 7d Base Course Materials 39

40 Phase II Study Test Results Permanent Deformation Deformation /Strain r2 r1 p1 p2 Cycles 40

41 Phase II Study Test Results Anticipated pavement field performance, based on lab test results: Fatigue (from best to worst): RPM/Fly Ash RPM Crushed Aggregate Rutting (from best to worst): RPM/Fly Ash Crushed Aggregate RPM Long-term implication: Deterioration of fly ash base course? Moisture effects on other base course? 41

42 Instrumentation Temperature 42

43 Instrumentation Moisture Content 43

44 Instrumentation Stress at the bottom of base RPM Crushed Aggregate RPM+FA 44

45 Construction Cost Construction Costs Initial Construction Cost of Base Courses $30,000 $25,000 $20,000 $15,000 $10,000 $5,000 Before Force Account After Force Account $0 RPM Crushed Aggregate Base Course Materials RPM+FA 45

46 Energy [MJ] Energy Consumption Comparison of Initial Energy Consumption 200,000 Initial Energy Consumption [MJ] 180, , , ,000 Force Account Processes (Equipment) Materials Transportation Materials Production 100,000 80,000 60,000 40,000 20,000 0 RPM Crushed Aggregate RPM+FA 46

47 CO2 [Mg] Greenhouse Gas Emission Comparison of Initial CO 2 Emission Initial CO2 Emissions [Mg] and Global Warming Potential Force Account Processes (Equipment) Materials Transportation Materials Production RPM Crushed Aggregate RPM+FA 47

48 Leachate Collection 48

49 Leachate Samples 49

50 Rotator 50

51 Inductively Coupled Plasma (ICP) 51

52 Leaching Results Leaching Results 52

53 Leaching Results Leaching Results 53

54 Column Leaching Test 54

55 Column Leaching Test 55

56 Column Leaching Test 56

57 Phase II Study Findings Field and lab tests confirmed that high carbon fly ash significantly increased the modulus of RPM Field and lab tests confirmed untreated RPM has higher modulus than crushed aggregate These observed pattern are supported by the various tests utilized, although there are quantitative differences between different tests Instrumentation results indicates that adding fly ash reduces the stress level on the top of subgrade, which could reduce the rutting in subgrade 57

58 Phase II Study Findings Using high carbon fly ash improved the bearing capacity of base course for construction In this field demonstration, using high carbon fly ash saved initial construction costs Leaching water contains heavy metals from all three different base course materials, including natural granite The leaching levels reduces as time passes High carbon fly ash section has lowest initial energy consumption and greenhouse gas emission 58

59 Further Study Continuously environmental monitoring Performance testing and monitoring Life cycle cost analysis Life cycle energy consumption Life cycle emission 59

60 Thank You 60