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Asphalt Paving Workmanship - Lessons to Learn
Transcript of Asphalt Paving Workmanship - Lessons to Learn
Too Lean? The road to perfection is bumpy
so what can we do to smooth
it out? Any suggestions? Problem 3 - Longitudinal Joints Q: How do we construct long-life pavement?
A: Improve workmanship. Last Humour Break Problems, Solutions and Tips Asphalt Paving Workmanship Thickness to be no less than 2.5 times the nominal aggregate size (50mm HL8, 30mm HL3) Roller Types 8hr = 960t 8hr = 1080t 8hr = 1200t 8hr = 1600t 8hr = 1760t HUMOUR BREAK TRUNK MONKEY Causes Insufficient compaction of the joint Environmental Reasons
traffic Workmanship Reasons
poor paving technique (screed elevation)
poor raking technique
poor rolling technique Environmental Factors Base Course: 2 Degrees Celsius and Rising Surface Course: 7 Degrees Celsius and Rising Traffic Humour Break We can rarely close the road to traffic Traffic may need to be flipped onto the live lane right after paving Temperature Limits Traffic Longitudinal Cracking - Other Factors Subgrade related
Alligator cracking Static Rubber Vibratory Constructing Good Joints
1.0 Compaction of the first lane Which is correct?? INCORRECT Correct In order to construct a durable longitudinal joint, it is necessary to compact the unsupported edge of the
first lane correctly. This is accomplished by extending the drum of a steel wheel roller over the
unsupported edge of the lane by approximately 150 mm.
If this is done, the asphalt concrete mix will not
move transversely and a crack will not form in the mix at the edge of the steel drum due to shear loading
at the edge of the drum. This lack of movement will allow the second lane to be properly placed and
compacted against the edge of lane 1. Constructing Good Joints
2.0 Lane Two - Overlap 2.1 - Thickness of Overlap - 6mm per 25mm final thickness. (Ultimately even once compacted)
2.2 - Width of Overlap - 25mm to 40mm - No raking needed 25 - 40mm 12mm Constructing Good Joints
3.0 Raking the Joint 3.1 If paved properly, joints do not need raking!!
3.2 Keep joints 6mm thick per 25mm final thickness.
Too low and it will result in voids (reduced compaction).
Too high and the roller will rest on the ridge and not compact laterally against the first lift. (50mm lift) What happened here?
Any guesses? Constructing Good Joints
4.0 Compacting the Joint The best place to position the roller, either a steel wheel roller or a pneumatic tire roller, is a short distance over the top of the joint from the hot side of the joint. For a rubber tire roller, the center of the outside tire of the roller, at the end of the roller with an even number of tires, is placed directly over the top of the longitudinal joint, as shown. Placing the roller in this position permits proper compaction of the mix at the joint as well as compaction of the hot mix on lane 2. This is an efficient way to compact both the mix at the joint and the mix in the mainline pavement. Constructing Good Joints
5.0 Other Considerations 5.1 Echelon Paving
5.2 Warm Mix
5.3 Joint Heaters
5.4 Wedge Joints
5.5 Joint Cutters WRONG RIGHT The first pass was on the left lane. During the 2nd pass (right lane), the screed was off and excessive raking was required. During 2nd pass rolling, the roller rested on the compacted 1st pass and did not compact the raked material. A Recipe for Raveling Low Density Area in Cold-Joint