The Right Fit - Joint Construction. Presented by: Todd Mansell, Sakai America, Inc.

Transcription

1 The Right Fit - Joint Construction Presented by: Todd Mansell, Sakai America, Inc.

2 Why joints? The weakest link in a pavement structure Raveling along longitudinal joints Ride quality on transverse joints

3 Erosion of mix at a longitudinal joint Photo courtesy of J.A. Scherocman

4 Erosion of mix along the joint E. Ray Brown

5 Three main objectives: 1. To get density 2. To build a smooth transition 3. To get density as quickly as possible

6 How do we get there? Pavement design Paver setup Best Practices for compaction

7 Pavement design Lift thickness to maximum aggregate size This is a specification problem, but it can also be a QC problem

8 Lift thickness to max agg. size

9 Lift thickness to max agg. size

10 Paver set up Starting out at the transverse joint Finishing for the day Tying into bridge decks & approaches Setting up for the longitudinal joint Automatic grade control Augers, end gates, extensions

11 Best Practices for compaction Different rolling patterns can be used on longitudinal joints Transverse joints are longitudinal joints turned sideways we roll them the same way whenever possible (cross-rolling)

12 Alternatives for compaction Roll from the hot side? Roll from the cold side? Pinch the joint? Leave the joint on the first pass?

13 Longitudinal Joint Construction

14 Why is it tough to get density? Mix temps are lower at edge of mat Getting non-segregated mix to the edge of the screed Getting enough mix to the edge Roll down and bridging of roller drums

15 What does it take to get density? Temperature Temperature Temperature

16 Temperature at outside edges

17 Auger extension and tunnel

18 More auger needed

19 More auger needed

20

21 Low density not enough mix Invert

22 Inverted joints collect water

23 Paving in echelon hot joints

24 Key factors for the construction of a durable longitudinal joint 1. Placing and compacting the unsupported edge 2. Placing and compacting the supported edge

25 1. Placing and Compacting the unsupported edges

26 Keep end gates on the paver down

27 Compaction of the unsupported edge The drum should be extended over the unsupported edge of the lane by approx. 6.

28 Overhanging the unsupported edge

29 Unsupported edges

30 Do not run the steel drum inside the unsupported edge

31 Do not run the roller inside the unsupported edge

32 Do not run the roller inside the unsupported edge

33 Do not run the steel drum directly on the unsupported edge

34 Movement of the mix at the unsupported edge James A. Scherocman

35 Do not run the rubber tire roller directly on the unsupported edge

36 Stay about 12 in from the unsupported edge with the rubber tire roller

37 Keep rubber tire inside edges

38 NEVER run any roller directly on the unsupported edge Steel Drum Rubber tires

39 2. Placing and Compacting the supported edges

40 Keep end gates on paver down

41 Overlap of mix from lane 2 to lane 1

42 Two different types of overlap Overlap 1: The thickness of the uncompacted mix Overlap 2: The amount of overlap of the mix from lane 2 over the top of lane 1.

43 Fluff Factor ¼ 1¼ 1 after compaction

44 Fluff factor cheat sheet

45 Overlap 2 The amount of overlap is in the range of ½ to 1½ With proper overlap, no raking ½ to 1½ Recommended Not Recommended

46 Too much overlap

47 Proper amount of overlap

48 Proper overlap no raking Save a lute man s back Reduce roller passes Improve tons per hour Better density at the joint without raking Lower permeability

49 No raking

50 Rolling from cold side is very inefficient

51 Disadvantages of rolling from the cold side When rolling from the cold side, bumps that are picked up by the roller drum (ie. rocks) will be transferred across the mat since the steel drum is rigid Mat is losing temperature Can not vibrate Slower production or more rollers needed or lower quality

52 Rolling from the cold side

53 Roll from hot side with 6 overhang

54 No raking rolling from hot side

55 No raking

56 The results

57 Excessive raking

58 Which side was paved first?

59 Do not rake flat!

60 Bridging drum - low density

61 Bump the joint Lane 1 Lane 2

62 Bumping the joint

63 Bumping the joint E. Ray Brown

64 Pull excess material away

65 Steel drum rollers can crush aggregate along the joint

66 Pneumatics force mix to the joint

67 Straddle the joint

68 Barely see the joint

69 Pneumatic on left, steel on right

70 Efficiency costs nothing: Roll from the hot side A 7-pass pattern versus a 5-pass pattern costs 17-ft per minute of production. Put the end gates down on the paver, match the joint with the proper horizontal overlap and fluff factor

71 Other considerations Saw cutting the longitudinal joint Notched-wedge joint (tapered joint) Joint heaters Wheel cutters on rollers Rolling 12 inside the SUPPORTED edge

72 Trimming the joint Should tack the exposed joint

73 Notched-wedge joint

74 Longitudinal joint heaters

75 Roller mounted wheel cutters E. Ray Brown

76 Compacting the center strip

77 Review longitudinal joints 1. Put the end gates down on the paver 2. Use auger extensions and tunnels 3. Overhang the edge 6 with steel drums 4. Stay 6 to 12 inside the edge with pneumatic tire rollers 5. Roll from the hot side 6. No raking (bump the joint if necessary)

78

79 Transverse Joint Construction

80 Paver setup starter blocks

81 Roll the joint cross ways

82 Stop traffic & roll cross-ways

83 Roll head on, SLOWLY!

84 Finish up for the day

85 Straight edge the joint to cut it back Use string line and automatic grade control to tie into bridge approaches

86

87 Things to think about

88 Paving in echelon hot joints

89 Rolling in echelon

90 Pneumatics can improve joint density

91 Use a cut-off shoe

92 to get this

93 then this

94 to get this!

95 SUMMARY 1. Look at the lift thickness & max aggregate size of the mix 2. Paver setup 3. Best practices for compaction Overhang the unsupported edges by 6 Roll from the hot side 99% of the time Minimize or eliminate raking Never roll with drum or tires directly on the edge 4. Try different rolling patterns!

96 Nice, no raking

97 Look at the roll down great!

98 NAPA Publications

99 Thank you!

100 APAM & NAPA Invest in your future