Extending Performance with
Proper Asphalt Compaction
Ken Walschlager
Milestone Contractors
Compaction is 90% rolling –
the other half is preparation…
Compaction is the process of reducing
the volume of a mass of material –
making it more dense.
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Design
Proper production
Sub-base/drainage
Good paving practices
Lift thickness
Compaction is key…
Better Compaction results in…
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Extended pavement’s life of service
Greater strength to support heavier loads
Increased resistance to rutting
Reduced permeability of water and air
Overall durability
Proper HMA Design
Different designs for different
applications
Special mix designs
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OG
Porous
SMA
4.75 Thin Lift
What about Warm Mix?
Proper Depth
Back to design…
Nominal Mix Design
Max Partical Size
Minimum Depth
Maximum Depth
Recommended Depth
Wedge/Level Max
9.5mm
12.5mm
1"
2"
1.5"
3"
12.5mm 19mm 25mm
19mm 25mm 37.5mm
1.5" 2" 3"
3"
4" 6"
2"
3" 4.5"
4.5" 6" 9"
4.75mm
9.5/12.5mm
.55"
1 1/8"
1"
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Proper Production
Stockpiles built correctly and tested?
Loader using correct methods?
Plant calibrated?
Right blend entered?
Proper loading of haul trucks?
Trucks equipped with tarps?
Proper Laydown
Surface properly prepared/tacked?
Mix dumped properly into buggy/paver?
Hopper not run empty?
Flow gates/auger speed set correctly?
Proper head of material?
Auger height correct/constant motion?
Paver operated at constant speed?
Depth as uniform as possible?
Proper Depth – it’s important
Deep enough for aggregate structure
Nominal Mix Design
Max Partical Size
Minimum Depth
Maximum Depth
Recommended Depth
Wedge/Level Max
9.5mm
12.5mm
1"
2"
1.5"
3"
12.5mm
19mm
1.5"
3"
2"
4.5"
19mm
25mm
2"
4"
3"
6"
25mm
37.5mm
3"
6"
4.5"
9"
4.75mm
9.5/12.5mm
.55"
1 1/8"
1"
????
Before rolling operations begin
Proper maintenance – read operators
manual
Operator Safety – get familiar with
roller
Check water system
Release agent?
Confirm frequencies
Rollers
Static
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Double drum
3 Wheeled
Pneumatic Tire
Vibratory
Oscillatory
Combination Rollers
Static Rollers
Variables
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Weight, speed, rolling pattern
When? OG, Porous, SMA, 4.75mm*
Vibratory Rollers
Variables
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Amplitude
Frequency
Speed (impact spacing)
Amplitude
Lower Amplitude
Variable
Higher Amplitude
Thinner <2"
Lift Thickness
Thicker >2"
Lower Grade
PG Grade/Viscosity
Higher Grade
Rounded/Gravel
Aggragates
Angular/Crushed
More open
Gradation
Dense
High
Ambient/Mix Temp
Low
Frequency
Impact Spacing
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Check owners manual.
Frequency (VPM)
2600
2800
3000
3200
3400
3600
3800
4000
1800
Impacts per foot
8
10
Feet/min
mph
Feet/min
mph
325
3.7
260
3.0
350
4.0
280
3.2
375
4.3
300
3.4
400
4.5
320
3.6
425
4.8
340
3.9
450
5.1
360
4.1
475
5.4
380
4.3
500
5.7
400
4.5
225
2.6
180
feet / min=VPM
VPM
impacts/ft
2.0
12
Feet/min
mph
217
2.5
233
2.7
250
2.8
267
3.0
283
3.2
300
3.4
317
3.6
333
3.8
150
1.7
Frequency
Correct impact spacing
Roller Speed
Paver = Plant = Trucking
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# of Passes of breakdown roller
Frequency setting
Tender Zone?
Roller width/paving width
Paver/Roller Speed
Do not out run your rollers.
3.5 mph roller
300ft/min – 3 wide to cover X 4 passes
300/12=25ft/min
85% rolling = 21 ft/min paver speed
(140tph)
300ft/min – 2 wide to cover X 4 passes
300/8=37.5
85% rolling = 32 ft/min paver speed
(211tph)
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Rolling
Turn towards the shoulder(away from traffic)
stopping at an angle.
Make sure vibration is turned off before
stopping.
Be sure not to turn wheel while stopped.
Break down when asphalt is at its hottest.
Cover entire mat with one pass before
starting 2nd.
Rolling cont.
Take previous stop marks out with next pass.
As paver moved forward, roll up to paver with
each pass to seal in heat.
Roll handwork as soon as possible.
Proper longitudinal joint construction.
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Stay on hot mat
Know when to “pinch the joint”
Cross-roll transverse joints.
Porous/OG
Static only
Strength through design with aggregate
structure and modified AC
Vibration can cause over compaction
Stone Matrix Asphalt
Static roll only
Roll as hot as possible
Typically no tender zone
Roll until cool – little concern of overrolling
Warm Mix
Easier to compact
Higher densities reported
Open to traffic sooner
Use same good rolling procedures as
HMA
Summary
Good design
Proper production
Proper paving practices
Good rolling techniques
Stay watchful – things change…
Thanks
Questions?