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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. • 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 applications • Special mix designs • OG • Porous • SMA • 4.75 Thin Lift • What about Warm Mix?
Proper Depth • 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
Before rolling operations begin • Proper maintenance – read operators manual • Operator Safety – get familiar with roller • Check water system • Release agent? • Confirm frequencies
Rollers • Static • Double drum • 3 Wheeled • Pneumatic Tire • Vibratory • Oscillatory • Combination Rollers
Static Rollers • Variables • Weight, speed, rolling pattern • When? OG, Porous, SMA, 4.75mm*
Vibratory Rollers • Variables • Amplitude • Frequency • Speed (impact spacing)
Frequency • Impact Spacing • Check owners manual.
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 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)
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 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 over-rolling
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?