HMA Pavement Construction Issues.ppt

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