extending performance with proper asphalt compaction ken walschlager milestone contractors
TRANSCRIPT
Extending Performance with Proper Asphalt Compaction
Ken WalschlagerMilestone 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. Design Proper production Sub-base/drainage Good paving practices Lift thickness
Compaction is key…
Better Compaction results in… 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 applicationsSpecial mix designs OG Porous SMA 4.75 Thin Lift What about Warm Mix?
Proper Depth
Nominal Mix Design 9.5mm 12.5mm 19mm 25mm 4.75mmMax Partical Size 12.5mm 19mm 25mm 37.5mm 9.5/12.5mmMinimum Depth 1" 1.5" 2" 3" .55"Maximum Depth 2" 3" 4" 6" 1 1/8"Recommended Depth 1.5" 2" 3" 4.5" 1"Wedge/Level Max 3" 4.5" 6" 9" ????
Back to design…
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 9.5mm 12.5mm 19mm 25mm 4.75mmMax Partical Size 12.5mm 19mm 25mm 37.5mm 9.5/12.5mmMinimum Depth 1" 1.5" 2" 3" .55"Maximum Depth 2" 3" 4" 6" 1 1/8"Recommended Depth 1.5" 2" 3" 4.5" 1"Wedge/Level Max 3" 4.5" 6" 9" ????
Before rolling operations begin
Proper maintenance – read operators manualOperator Safety – get familiar with rollerCheck water system Release agent?Confirm frequencies
Rollers
Static Double drum 3 Wheeled Pneumatic Tire
VibratoryOscillatoryCombination Rollers
Static Rollers
Variables Weight, speed, rolling pattern When? OG, Porous, SMA, 4.75mm*
Vibratory Rollers
Variables 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 Check owners manual.
Impacts per foot
Frequency (VPM) Feet/min mph Feet/min mph Feet/min mph2600 325 3.7 260 3.0 217 2.52800 350 4.0 280 3.2 233 2.73000 375 4.3 300 3.4 250 2.83200 400 4.5 320 3.6 267 3.03400 425 4.8 340 3.9 283 3.23600 450 5.1 360 4.1 300 3.43800 475 5.4 380 4.3 317 3.64000 500 5.7 400 4.5 333 3.8
1800 225 2.6 180 2.0 150 1.7
feet / min=VPM VPM impacts/ft
8 10 12
Frequency
Correct impact spacing
Roller Speed
Paver = Plant = Trucking # 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 roller300ft/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 passes300/8=37.585% rolling = 32 ft/min paver speed(211tph)
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. Stay on hot mat Know when to “pinch the joint”
Cross-roll transverse joints.
Porous/OG
Static onlyStrength through design with aggregate structure and modified ACVibration can cause over compaction
Stone Matrix Asphalt
Static roll onlyRoll as hot as possibleTypically no tender zoneRoll until cool – little concern of over-rolling
Warm Mix
Easier to compactHigher densities reportedOpen to traffic soonerUse same good rolling procedures as HMA
Summary
Good designProper productionProper paving practicesGood rolling techniquesStay watchful – things change…
Thanks
Questions?