best practices : paving and rolling · 09/03/2019 · paving by the numbers step 2 •adjust tow...

BEST PRACTICES : PAVING AND ROLLING

PAVING PRODUCTS

Understanding the Paver

Keep the paver in good

condition

• Scheduled inspection &

maintenance

• Follow maintenance

guidelines

PAVING PRODUCTS


Basic Paver Functions

• Self-leveling

• Material feed

PAVING PRODUCTS


Tractor Self-Leveling

• Screed is free to rise & fall

• Constant line of pull when

set up properly

• Smooth surface over

irregular grade

PAVING PRODUCTS


Free-Floating Screed

• Screed position determines

mat thickness

• Screed position is constant as

long as all factors remain

constant

PAVING PRODUCTS


Factors Affecting

the Screed

• Paving speed

• Head of material

• Screed adjustments

• Mix design

• Mix temperature

• Air temperature

• Grade temperature

PAVING PRODUCTS

Factors Affecting Screed

Constant Speed

• Shear factor is constant

• Depth remains constant

PAVING PRODUCTS


Increased Speed

• Shear factor decreases

• Depth decreases

PAVING PRODUCTS


Decreased Speed

• Shear factor increases

• Depth increases

• Amount of depth change varies

with amount of speed change

• Mix design also affects shear

factor

PAVING PRODUCTS


Real World Paving

• Do not panic

• Stay with the plan

• Get rid of trucks in an

orderly fashion

• Establish a uniform trucking

pattern

PAVING PRODUCTS


Correct Head of Material

• Half auger level

• Constant resistance

• Constant depth

PAVING PRODUCTS


Head of Material Decreased

• Resistance decreased

• Depth decreases

PAVING PRODUCTS


Head of Material Increased

• Resistance increased

• Depth increases

PAVING PRODUCTS


Paving Speed

• Paving speed constant

• Feeder system set to match

paving speed

• Changes in paving speed may

require feeder system

adjustments

PAVING PRODUCTS


Adjustable Augers

• Adjustable height augers

help mat texture

• Help prevent segregation

PAVING PRODUCTS


• Start at 50 mm (2") above

level of mat prior to

compaction

• Adjust up or down

depending on mix type

and appearance of mat

200mm (8”)

50mm (2”)

50mm (2”) 304mm (12”)

PAVING PRODUCTS


Auger Speed

• Auger speed uniform

• 20-40 rpm

• Auger speed too high or

too low can cause stripes

in the mat

CONSISTENCY!!!!CONSISTENCY!!!!CONSISTENCY!!!!CONSISTENCY!!!!CONSISTENCY!!!!

CONSISTENT SPEED!CONSISTENT HEAD OF MATERIAL!

= CONSISTENT RESULTSCONSISTENCY!!!!CONSISTENCY!!!!

Paving by the Numbers

STEP 1

• Heat the screed

✓Electric element

✓Diesel Fired

✓Liquid propane

• Prevents asphalt

sticking to screed


STEP 2• Adjust Tow Point

Cylinders

✓ Adjust both tow points to “0” then raise the tow point the thickness of the mat to be laid.

✓ Each mark is 20 mm. Example: If the mat being laid is 50 mm (2 in), adjust the tow point to 50 mm (2 in) above “0”


STEP 3•Set Paving Width

✓Set the extenders width according to job specs

✓Use scales on extenders

✓Equal extender width on both sides whenever possible.

Rear

Mounted

Extensions

Front

Mounted

Extensions


STEP 4•Set Main Screed

Crown

✓Set screed crown to job specs

✓Scale location changes depending on screed


STEP 5•Set Extender

Height✓Rear mounted

extenders 6 mm (1/4 in) above zero

✓Front mounted extenders 6 mm (1/4 in) below zero

✓Switch located in each screed control box

Front

Mounted

Extenders

Rear

Mounted

Extenders


STEP 6•Set the Extender

Slope

✓Set extender slope to job specs

✓Scale location changes depending on screed

Rear

Mounted

Extenders

Front

Mounted

Extenders


STEP 7•Lower the Screed ✓Lower the screed

onto the starting reference

✓Select a starting reference that is the proper thickness

✓Support main screed and extender screed

✓Reference length 0.9 - 1.2 m (3-4')

Paving by the NumbersSTEP 7• Lower the Screed

✓Move the machine forward to remove the slack from the tow point


STEP 8•Null The Screed

✓Turn one thickness screw until no resistance is felt

✓Repeat for the other depth crank

✓Check the first side again

✓Null one side at a time


STEP 8•Null The Screed

✓Turn depth crank in direction of increase until tension is felt

✓Set other depth crank the same way

❖NOTE: Optional thickness screws allow clockwise or counter-clockwise increase


STEP 9•Position End Gates

✓Lower end gates to contact grade

✓Raise or lower guide tubes to create float space

✓75 mm (3 in) gap between ski and guide tube

75 mm (3 in)


STEP 10• Set Auger Height

• Auger height affects mat texture

✓Auger height 50 mm (2 in) above mat is right for most mixes

✓Fine tune according to mix


STEP 11• Position Feeder

Sensors

• Sonic feeder sensors

✓Perpendicular to the live material flow.

✓460 mm (18 in) - 760 mm (30 in) away from the material

✓Target moving material


STEP 12• Manually Fill Auger

Chamber

✓With the machine at low idle

✓Use conveyor manual override switches on the operator’s console

✓Convey material out until material just touches auger shaft



Chamber

✓With the machine at low idle

✓Manually auger material across screed face

✓Auger material out to establish 1/2 level

✓Do not overfill



Chamber

✓Using a shovel, hand fill area between last auger and end gate

❖NOTE: Do not fill in area in front of screed extender on rear-mounted extender screeds

No Fill

Area


STEP 13• Set Feeder Controls

✓Place conveyor switches in Auto (up)

✓Place auger switches in Auto (up)



✓Adjust conveyor ratio control dials to 10 o'clock position



✓Adjust mix height dials to 10 o'clock position


STEP 15• Pull Off Starting

Reference

✓Speed control dial at zero

✓PAVE mode, high idle, brakes released, and propel lever full forward.

✓Turn speed dial up until calculated paving speed is reached



Reference

• As paving begins

✓Operator checks center area of auger chamber.

✓Adjust conveyor ratio controls if necessary to maintain material level at 1/2 auger



Reference

• As paving stabilizes

✓Check auger speed

✓Keep auger speed in 20-40 RPM range

✓Avoid ON / OFF operation

Paving by the NumbersSTEP 15

• Pull Off Starting Reference

• Screed personnel

✓Check for transition marks

✓Mat should be uniform

No Separation Marks In Mat

(Rear Mounted Extenders)

No Separation Marks In Mat

(Front Mounted Extenders)



• Extender too low, mark in line with inner edge of extension

✓Raise extender until transition line disappears

Extender Screeds Too Low


Extender Screeds Too Low




• Extender too high, mark in line with outer edge of main screed

✓Lower extender until transition line disappears

Extender Screeds Too High


Extender Screeds Too High



✓Keep speed constant

✓Speed changes cause bumps or dips

✓Adjust feeder system if speed must be changed.

Paving Products

How Compaction Affects

Smoothness • Transverse Joints

• Patterns

• Stops

Paving Products

Joint Compaction -- Team Effort

• Start with good paving

and minimal hand

work

• Mat depth must allow

for rate of compaction

• Rule of thumb: 1/4” of

compaction for each

1” mat depth

Paving Products

Transverse Joint Compaction

• Whenever possible

roll from the side in

static mode

• Pinches joint

• Rolling straight --drum

tends to bump over

joint

Paving Products


Hot Cold

Joint

12”

#1

Paving Products


Hot Cold

Joint

30”

#1 #2

Paving Products

Hot Cold

Joint

30”

#1 #2

60”

#3


Paving Products


Paver

Hot Cold

Joint

Paving Products


• Straight edge tells

the story

• Too high -- more

rolling may help

• Too low -- hand work

needed to fill in

Paving Products

Bends, Tight Radius Compaction

• Street project paving

12- feet wide

• 66” drum width

breakdown roller

• Operator followed

radius in continuous

pass

Paving Products


• Outside edge of drum

is shoving hot mix

• Mat distortred and

cracked

Paving Products


• Roller operator trained

to roll straight into

radius

• Pattern takes more

passes but leaves

smooth tight mat

Paving Products

Bends or Junctions


Paving Products

Roller Reverse Marks

• 84-inch drum on 12-foot mat yields small reversing angle

• Deep mark left by outside drum edge during turn

• Reversing close to paver on hot, tender mix accentuates mark left by drum edge

• Marks may not clean up during successive passes

Paving Products

Roller Reverse on Adjacent Cold Mat

• Paving westbound lane

breakdown roller could

reverse on cold eastbound

mat

• Less marking on hot mat

• Profilograph showed less

deviation on westbound lane

due to fewer roller marks

Paving Products

Roller Reverse on Shoulder

• 12-foot driving lane and 6-

foot shoulder with 18”

slough

• All compactors stop /

reverse on shoulder

• No stop marks in driving

lanes

• Project earned 100% of

available ride bonus

Paving Products

What We’re Trying to Avoid

• Breakdown roller pattern

• Stops too close together

• Hard to erase completely

with finish rolling

Paving Products

Compactor Stopped during Paver Stop

• Breakdown roller caught up to paver during stop

• Parked on mat 100’ behind paver

• Drums dented mat

Six minute roller

stop

Paving Products

Thermal Effect of Roller Stop

• Drums act as heat sink on mat

• Two cold dents created

• P2 and P3 150o F

• Dents will not be removed by next roller passes

Paving Products

Effect of Roller Stop on Smoothness

• Dents left by drums are easily identified -- two sets of bumps and dips about 8 feet apart

• 0.18 added to score in 8 feet of paving

• Proves that finish roller could not clean up these marks

Paving Products

Stopping for Water

• Always try to find a place

to park off the driving lane

• Shoulders, turn-outs,

driveways

Paving Products

Breakdown Roller Stopped for Water

• Compactor stopped 10

minutes on mat for water

• Mat cooled to 150 o F under

the drums

• Drums created depression

and bump

• Sometimes this is

unavoidable -- right?

Paving Products

Thermal Image of Roller Stop

• Drums act as heat sink

• Rapid loss of heat in

mat under drums

• Intermediate and finish

passes will not remove

bumps

Label Emissivity Background

Average

P1 0.94 84.94 124.36

P2 0.94 84.94 151.37

P3 0.94 84.94 162.85

P4 0.94 84.94 152.44

Paving Products

Intersection Tie-ins

• Note: small roller

working on tie-in to

intersection

Paving Products

Rolling onto Mainline Mat

• Intersection roller

stopped/reversed

on hot mainline mat

• Operator given

instructions to roll

parallel to joint

Paving Products

How Compaction Affects

Smoothness • Plan your work to match

the application

• Ask questions if you’re not

sure

• Stop rolling when you see

a problem

• Consult the supervisor or

QC person

best practices : paving and rolling · 09/03/2019 · paving by the numbers step 2 •adjust tow...

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