Post on 14-Jan-2017
HMA Pavement Construction IssuesHMA Pavement Construction Issues
• Presented by:
Robert Sauber
Supervising EngineerEngineer
Bureau of Materials
Develop a Strategy
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Construction requirementsConstruction requirements
• Lane closure hours and environmentalLane closure hours and environmental regulations often limit treatment selection
• Select a buildable treatment that provides• Select a buildable treatment that provides the largest agency and user benefitC t ti t d i i htti• Constructing pavements during nighttime lane closures reduces quality
• Poor working conditions resulting in loss of talented workers
Considerations with Full Road Closure
• Not amendable to all construction situationssituations– The availability of adequate alternate routes
• A solid management plan• A solid management plan– Done on an accelerated schedule
Scheduled on a 24 hr work basis potential for• Scheduled on a 24-hr. work basis, potential for impacts to local residents are concerned.
• Ensure all the needs to be met throughout project g p jduration
– Balance the increased load on the network • Increased traffic densities on alternate routes must
be assessed, planned for, and managed.
Benefits of Full ClosureBenefits of Full Closure• Reduced project duration • Increased worker productivity• Increased worker productivity • Improved safety
I d d t lit• Improved product quality • Positive public sentiment • Increased workspace and flexibility • Reduced impact on construction p
travelers • Cost savingsg
Full Road Closure Time Savings
Milling and Profile MillingMilling and Profile Milling
• Milling is used to remove worn out surfaceMilling is used to remove worn out surface material and fix cross slope and profile– 2007 Specs eliminates 20+ milling itemsp g– Ranges now specified; 0-3”, >3”-6”, >6”– Plans should indicate grade control pointsg p
• Profile milling is used to remove ruts and corrugation and/or improve smoothnessg– Normally included for bridge undercuts where
lane closure time is limited, thick lifts placed
Paver Production Rates (approx )Paver Production Rates (approx.)
• Microsurfacing- up to 7 lane miles/shiftMicrosurfacing up to 7 lane miles/shift• Novachip- up to 5 lane miles/shift
HMA t 3 l il / hift• HMA- up to 3 lane miles/shift• Plant production outpaces paver placement• Number of haul trucks is critical• MTV helps to reduce the number of trucksMTV helps to reduce the number of trucks
Material Transfer VehicleMaterial Transfer Vehicle
• Helps to maintain consistent paver speedHelps to maintain consistent paver speed• Helps mixture and temperature
segregation by remixing the materialsegregation by remixing the material• Prevents haul trucks from bumping paver• Stores 1½ loads of material on site
But…
• Extremely heavy when loaded• Material loses 20oF in the processMaterial loses 20 F in the process
Weather LimitationsWeather Limitations
• Microsurfacing the most sensitive to coldMicrosurfacing the most sensitive to cold temperatures or heavy rain
• Open Graded Friction Course and• Open Graded Friction Course and Novachip sensitive to cold weather T k C t 64 22 ill t dh h• Tack Coat 64-22 will not adhere when surface is damp from rain or milling
• Thicker lifts of HMA should be placed in cool weather
Milling Machineg
Cutting DrumCutting Drum
Scabs after milling
Proper Tack Coat Coveragep g
Poor Tack Coat Coverage
Good/Bad Tack Coat Coverageg
Paver Augerg
Screed Extension
Paver HopperPaver Hopper
Hopper Insert for MTVHopper Insert for MTV
Paver Push Roller & Hitch
Paver Gearbox
Gear Box StreakGear Box Streak
Gearbox Streak
Echelon PavingEchelon Paving
Bad Longitudinal Joint
Notch Wedge Apparatus
Notch Wedge Joint
Ski used for grade controlg
MTV: Blaw Knox MC 30
MTV- Shuttlebuggyggy
Shuttlebuggy Auger
Steel Wheel Roller- Vibratoryy
Pneumatic tire roller
Pneumatic tires
Nuclear Density Gauge: QCy g
Fat Spots- Bleeding or FlushingFat Spots Bleeding or Flushing
Roller Marks
Poor Longitudinal JointPoor Longitudinal Joint
Patched Longitudinal Jointg
Poor Texture
Ravelingg
Freshly Placed HMAFreshly Placed HMA
Mat Temp at Transverse JointMat Temp. at Transverse Joint
Nuclear Density TestingNuclear Density Testing
Temperature SegregationTemperature Segregation
Temperature SegregationTemperature Segregation
MTV Dumping into PaverMTV Dumping into Paver