block 18 placement 13
TRANSCRIPT
Construction Placement 1
Placement of HMA Mixes
Senior/GraduateHMA Course
Construction Placement 2
Safety - First, Last and Always...
Don’t depend on drivers to avoid you. Play it safe.
Watch your back and your buddies.
Construction Placement 3
Push Rollers
Tractor
Hopper
Tow Point
Side ArmsConveyors
Screed
Depth Crank
Augers
Construction Placement 4
TRACTORTRACTOR
HOPPERHOPPER
PUSH ROLLERPUSH ROLLER
TOW POINTTOW POINT
SIDE ARMSIDE ARM
SCREEDSCREED
DEPTH CRANKDEPTH CRANK
AUGERAUGER
CONVEYORCONVEYOR
Construction Placement 5
Tractor Unit
Construction Placement 6
Construction Placement 7
Push Roller
Truck Hitch
Construction Placement 8
Truck hitch engaged
Construction Placement 9
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Construction Placement 17
Hopper Wings
Slat ConveyorsHopper GatesAugers
Screed Plate
ProportionalFeed Control
Material Flow
Construction Placement 18
Operational Principles of the Operational Principles of the ScreedScreed
• Self-leveling Concepts Self-leveling Concepts • Screed Response versus Distance Screed Response versus Distance • Forces Acting on a ScreedForces Acting on a Screed
Construction Placement 19
Self Leveling - Rubber Tired Paver
Rear Drive Tires Front Bogie Wheels
Line of Pull
Construction Placement 20
Detail of Screed PathDetail of Screed Path
Tow Point PathTow Point PathStep Amplitude = 100%Step Amplitude = 100%
L = Leveling Arm LengthL = Leveling Arm Length
Screed PathScreed PathDirection of PavingDirection of Paving
63%63% 87%87%
6L6L5L5L4L4L3L3L2L2L1L1L00
96%96% 98%98% 99%99%
L
Construction Placement 21
1 inch movement at Tow Point
1/8 inch movement at Leading Edge of Screed
Construction Placement 22
Main Forces Acting on Screed Main Forces Acting on Screed
1. Speed of Paver1. Speed of Paver
2. Head of Material2. Head of Material
- - Shear resistanceShear resistance
3. Angle of Attack 3. Angle of Attack
4. Other Forces 4. Other Forces – Pre-compaction Pre-compaction – Screed WeightScreed Weight
Construction Placement 23
Tow Point
Screed DepthCrank
Pivot Point
F1
F2
F3
Construction Placement 24
Constant Head of Material Volume
Head of Material Volume Too High
Head of Material Volume Too Low
Correct Depth ofMat Maintained
Screed Rises Due toExcess Material ForcedUnder Nose of Screed
Screed Settles Due toInadequate Supporting
Material
Construction Placement 25
Correct Correct ElevationElevation
Auger Auger OverloadedOverloaded
Auger Auger UnderloadeUnderloade
dd
Construction Placement 26
Travel
Angle of Attack
Construction Placement 27
Construction Placement 28
HOT STOP ConceptHOT STOP Concept
• If constant material flow cannot be If constant material flow cannot be maintained, before HMA mix drops in maintained, before HMA mix drops in hopper below gates...hopper below gates...
• ““Hot Stop” the paver as quickly as Hot Stop” the paver as quickly as possiblepossible
• Wait for next truckWait for next truck• Pick up truck on run and resume speed as Pick up truck on run and resume speed as
quickly as possible.quickly as possible.
Construction Placement 29
Screed Control SystemsScreed Control Systems
• Who’s Responsible for Changes Who’s Responsible for Changes • Sticking the Mat Sticking the Mat • Manual Controls Manual Controls • Automatic Controls Automatic Controls
Construction Placement 30
Construction Placement 31
Pavement ProfilePavement Profile
Direction of PavingDirection of Paving
Construction Placement 32
Detail of Screed PathDetail of Screed Path
Tow Point PathTow Point PathStep Amplitude = 100%Step Amplitude = 100%
L = Leveling Arm LengthL = Leveling Arm Length
Screed PathScreed PathDirection of PavingDirection of Paving
63%63% 87%87%
6L6L5L5L4L4L3L3L2L2L1L1L00
96%96% 98%98% 99%99%
L
Construction Placement 33
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Construction Placement 35
Types of Grade Reference Types of Grade Reference
• Stringline Stringline • Mobile referenceMobile reference• Joint matching shoe Joint matching shoe • Sonic sensorSonic sensor• LaserLaser
Construction Placement 36
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Construction Placement 42
Grade Sensor - Side Arm Mount
Construction Placement 43
Grade Sensor - Screed End Mount
Construction Placement 44
Construction Placement 45
Ultrasonic Grade SensorUltrasonic Grade Sensor
Construction Placement 46
Balancing ProductionBalancing Production
TruckingTrucking CompactionCompaction
PavingPavingHMA HMA FacilityFacility
Construction Placement 47
QUESTIONS ?