principles of paving
Download
Skip this Video
Download Presentation
Principles of Paving

Loading in 2 Seconds...

play fullscreen
1 / 44

Principles of Paving - PowerPoint PPT Presentation


  • 486 Views
  • Uploaded on

Principles of Paving. Paver System Five. Grade Control Systems Tremendous benefits to the paving contractor: Increase efficiency and productivity Control Material Quantities Improve smoothness and rideability Increase jobsite safety. Control Sensors. Slope Control. Laser Control.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' Principles of Paving' - israel


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
paver system five
Paver System Five
  • Grade Control Systems
  • Tremendous benefits to the paving contractor:
  • Increase efficiency and productivity
  • Control Material Quantities
  • Improve smoothness and rideability
  • Increase jobsite safety

Control Sensors

Slope Control

Laser Control

= Theanswer for perfect, smooth paving?

Sonic Control

Smoothtrac

Sonic Averaging System

paver system five1
Paver System Five

Good Paving Practice

Grade Control

Decent paving

Control Sensors

Control Sensors

Control Sensors

=

+

Fair paving

=

+

Great paving!

=

+

principles of paving1
Principles of Paving
  • Good principles of paving must come BEFORE Grade Control
  • Paving is a TEAM project
  • Grade control is a great tool to help the paving team:
    • be more efficient
    • control material quantities
    • provide a smoother surface

Train the entire TEAM!

paver components
Paver Components
  • Asphalt Paver
  • The paver has two primary components:
  • Tractor
  • Screed
paver tractor
Paver Tractor
  • Tractor has two primary functions
  • Material Handling
  • Forward Movement
paver tractor1
Paver Tractor
  • Asphalt distribution
  • The paver typically receives the asphalt:
  • directly from a truck
  • by a pickup machine (windrow elevator)
paver tractor2
Paver Tractor
  • Asphalt distribution
  • The asphalt is received into the paver’s hopper
  • Hopper is a holding station for the asphalt
  • The operator tilts the hopper to deliver material into the feeder conveyor
paver tractor3
Paver Tractor
  • Asphalt distribution
  • Feeder conveyors distribute the asphalt to the augers
  • The augers spread the asphalt in front of the screed
  • End gates contain the material at the outer edge of the screed
screed components
Screed Components
  • Paver Screed
  • Function of the screed is mat laydown
  • Screed has several components
screed concept
Screed concept
  • The screed floats on the asphalt as it passes under the screed plate
  • The screed will “self-level” and maintain a thickness based on the forces acting on the screed.

Floating, Self-Leveling Screed

screed concept1
Screed Concept
  • The desired thickness is controlled by the screed angle of attack
  • As the angle of attack is increased or decreased, the screed will float up or down changing the thickness

Screed angle of attack…

…controls mat thickness

changing angle of attack
Changing Angle of Attack
  • The angle of attack can be changed by:
  • The manual crank
  • The hydraulic cylinder at the tow point
screed concept2
Screed Concept

If the angle of attack is…

increased,

decreased,

Mat thickness decreases

Mat thickness increases

floating self leveling screed
Floating, Self-Leveling Screed
  • The paver tractor, and therefore the screed tow point, travel over the existing “rough” surface
  • The floating screed doesn’t react immediately to the variations in the tow point path
  • The floating screed seeks it’s own level, smoothing out small humps and bumps.
floating self leveling screed1
Floating, self-leveling screed
  • The floating screed naturally cuts off high spots and fill in low spots.

Cuts off high spots

Fills in low spots

screed reaction
Screed Reaction
  • Tow point “step disturbance” and screed reaction
  • Two point is changed by a unit of one (1)
  • Net effect = the angle of attack has been changed
screed reaction1
Screed Reaction
  • Example of tow point “step disturbance” and screed reaction
  • Two point is changed by a unit of one (1)
screed reaction2
Screed Reaction

Example of change in angle of attach by turning manual crank and screed reaction.

checking mat depth
Checking Mat Depth
  • Goal is to “average” a particular paving thickness
  • Always check several places, horizontally and laterally
adjusting mat depth
Adjusting Mat Depth
  • Once an adjustment is made – GIVE THE SCREED TIME TO REACT!
adjusting mat depth1
Adjusting Mat Depth

Goal – Provide smoothness and compaction, while hitting target tonnage for entire project!

  • Determine average depth by measuring tons/mile
  • Make small adjustments based on calculation
floating self leveling screed2
Floating, Self-Leveling Screed

Left alone, the screed will self-level and assume a thickness based on forces that are acting on the screed.

  • What are these forces?
forces acting on the screed
Forces Acting on the Screed

There are four major forces acting on the screed

forces acting on the screed1
Forces Acting on the Screed
  • If any one of these forces change, the mat thickness will change.
  • But in “real life” job applications, these forces cannot always remain constant.
tow point force
Tow Point Force

If the forward speed…

increases;

mat thickness will decrease

decreases;

mat thickness will increase

Goal - Non-stop, continuous paving!

tow point force1
Tow Point Force

Goal - Non-stop, continuous paving!

  • Determine paving speed based on plant supply in tons/hour
  • Regulate trucks to the paving supply and operation, not the paving operation to the trucks

Plant supply = 210 tons/hour

Paving speed = 25’/minute

tow point force2
Tow Point Force

Maintain smooth truck exchange!

Bump in matat every truck exchange

(probably “caused by faulty grade control!”)

in motion switches
In Motion Switches
  • While stopped waiting for trucks, the screed will settle slightly
  • Screed goes down, the tracker will also go down slightly
in motion switches1
In Motion Switches
  • Grade control would want to drive the tow cylinder up to compensate
  • The paver’s In-Motion switch stops the valve electrical signal
  • A timer initiates the electrical signal after the paver is in-motion

X

head of material force
Head of Material Force

Maintain a CONSISTANT head of material

head of material force1
Head of Material Force

Maintain a CONSISTANT head of material

head of material force2
Head of Material Force

Maintain a CONSISTANT head of material

reaction of material force
Reaction of Material Force
  • Mix Characteristics
  • Gradation
  • Segregation
  • Mix Temperature
weight of the screed force
Weight of the Screed Force

Compaction Force = Pounds per square inch

weight of the screed force1
Weight of the Screed Force
  • Compaction Force = Pounds per square inch
  • How can the weight force change? (lbs per square inch)
  • People climbing on and off the screed can have a small effect on overall screed weight
weight of the screed force2
Weight of the Screed Force
  • Screed extension
  • Changing screed width changes the compaction force - Lbs per square inch
roller compaction
Roller Compaction
  • Good rolling practice is critical to the quality of the mat
roller compaction1
Roller Compaction
  • A freshly laid, smooth mat will reflect some of the original surface after rolling
  • Quality of the base being paved affects smoothness
  • Multiple lifts help to minimize these effects
mechanical condition of the paver
Mechanical condition of the Paver
  • The paving machine itself needs to be in good shape and adjusted correctly
  • Feeder system
    • Hopper, flight chain operation and adjustment, augers, etc.
    • Operation and adjustment of feeder controls
  • No excessive wear on screed components
    • Screed plates
    • Thickness control screws, bearings, and bushings
    • Screed pivot point bushings
  • Screed adjustment
    • Strike off plates
    • Screed flatness
    • Screed extensions adjusted properly, elevation and slope
paver system five2
Paver System Five

Good Paving Practice

Grade Control

Decent paving

Control Sensors

Control Sensors

Control Sensors

=

+

Fair paving

=

+

Great paving!

=

+

paver system five3
Paver System Five
  • Tow point is smoothly controlled to a desired path:
  • Curb
  • Stringline
  • SAS smoothing out existing surface

Then let the floating, self-leveling screed do it’s job!

best paving practices
Best Paving Practices
  • Good mechanical condition of the paver
  • Minimize changes in the natural forces on the screed
  • Non-stop, continuous paving
  • Good, smooth truck exchange
  • Constant paving speed
  • Constant head of material
  • Consistent mix characteristics
  • Good rolling techniques
  • Good quality of sub-base
  • Understand proper setup and operation of Grade Control
ad