Block 20 Types of Rollers 13
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Transcript of Block 20 Types of Rollers 13
Construction Compaction Equipment 1
HMA Compaction
Types of Rollers & the Compaction Process
Senior/GraduateHMA Course
Construction Compaction Equipment 2
What you will learn….
• The different types of compactors• How compactors compact• Variables associated with compaction• How density is controlled in the field
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Types of Rollers
• Static Steel Wheel • Pneumatic – Rubber Tired• Vibratory
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How Do Rollers Compact?
By applying their load
over a given area!
(Contact Pressure)
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Static Steel Wheel Roller
• Contact Pressure • Operation
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Pounds per Linear Inch (PLI)
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Pounds Per Linear Inch (PLI)
• Example:– A 8 ton roller with two, 50 inch wide drums.– In this case, 60% of the mass is on the
drive drum and 40% is on the guide drum.– Calculate the PLI for each roll and for the
roller in total.
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Pounds Per Linear Inch (PLI)
• 8 tons x 2000 lbs/ton = 16,000 lbs.• For each drum
60% x 16,000 lbs. / 50 inches = 192 PLI
40% x 16,000 lbs. / 50 inches = 128 PLI • For total roller
16,000 lbs. / (50 +50) = 160 PLI
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Speed of Roller
• Speed kills compaction forces• Dwell time• Pressure, impact, manipulation
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Travel
Frictional force turns trailing drum
Non-Non-powered powered
drumdrumPowered
Drum
WW R
R
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Pneumatic Tired Rollers
• Wheel load• Tire design • Inflation pressure• Contact area
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Vibratory Rollers
• Amplitude • Frequency• Impact Spacing • Operation
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01-00 6 - 47
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Frequency, f = the number of hertz (cycles/s)--a single cycle is one full rotation of the eccentric weight. Frequency = 1/T
Amplitude, A = the maximum deviation from position at rest -- one-half the total movement.
Amplitude(A)
Time
U pD
ow
n
Time (T) For Full Cycle
Mo
vem
ent
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AMPLITUDE
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DIRECTION OF TRAVEL
FREQUENCY
Impact Spacing
High FrequencyLow Frequency
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Typical Compaction Process
Compactive Force PressureVibration
PressureManipulation
Pressure
TemperatureZones
300° - 240°F 240° - 190°F 170 - 150°F
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Compaction Variables
• Roller Speed • Number of Coverages• Rolling Zone • Rolling Pattern
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Typical Range of Roller Speeds(miles per hour)
Type of Roller Breakdown Intermediate Finish
Static Steel Wheel 2 to 3.5 2.5 to 4 3 to 5
Pneumatic 2 to 3.5 2.5 to 4 4 to 7
Vibratory 2 to 3.5 2.5 to 3.5 3 to 51
1 1 Operated in static modeOperated in static mode
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One Coverage
How many passes of the roller are How many passes of the roller are needed to cover the width of the mat needed to cover the width of the mat one time ?one time ?
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Pass & Coverage DefinedW
idth
of m
at Pass1
Pass 2Make up Pass 5
Pass 3
Pass 4
This is a 5 pass pattern that provides 2 complete coverages.
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75 m
15 m
Typical Rolling Zone
Paver
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Test Strip Construction
• Simulating Actual Conditions • Establishing Roller Patterns • Calculating Effective Roller Speed
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1
4
2
3
5
6
CROWN2-lanes
One Roller Coverage
Drum Width = 72 inches
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How Many Repeat Coverages to Assure Density?
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Density
High
Low
DensityPassing
1 2 43 5 6
Roller Passes
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Balancing Production
Trucking Compaction
PavingHMA Facility
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Questions?