Designed with the Paving Professional in Mind Achieving Quality Joint Construction Nova Scotia Asphalt User Producer Association 6th Annual Meeting Larry Spring LB Performance Paving Division of VT Leeboy Designed with the Paving Professional in Mind

THE HEAD OF MATERIAL IS THE MASS OF PAVING MATERIAL THAT LIES DIRECTLY IN FRONT OF AND SPANS THE ENTIRE WIDTH OF THE SCREED. NINETY-FIVE TO NINETY-EIGHT PERCENT OF ALL MAT FLAWS ORIGINATE FROM PAVING WITH AN IMPROPER HEAD OF MATERIAL. Slide 2

Correct Head of Material Required Depth Required Density Increased Depth Decreased Density Head of Material Too High Decreased Depth Increased Density Head of Material Too Low

Segregation

Use of Auger Tunnels to Control Material Flow to the Outer Edges of the Screed MATERIAL FLOWING FORWARD MATERIAL CONTROLED BY TUNNEL

Auger/Conveyor Overview Hopper at Least 1/3 Full Augers Built to Suit Width of Screed - Material Level with Auger Shaft Conveyors Kept Filled Slide 6

Indication of end of load. Lack of Material at Augers Slide 7

Joint Construction TRANSVERSE JOINT CONSTRUCTION

Possible Fretting Here Transverse or Overnight Joints Alternative Construction Possible Fretting Here Direction of Travel End of 1st Mat Start of New Mat Wedge Transverse Joint Wood Ramp (Hand Shaped)

Constructing a Transverse Joint Clear & Square Constructing a Transverse Joint Add Joint Paper Form the Wedge Roll the Joint

Preparation of end of pass joint 4 3 2 1 Preparation of end of pass joint

Clean & Tack Coat Vertical Edge Resuming Paving at a Transverse Joint Wedge Removed Compacted Mat Clean & Tack Coat Vertical Edge Ref: Joints pg. 6

Setting the Screed for work Support the screed throughout it’s width using wood starting blocks or lathes. Center tow point cylinders. Screeds should be set up correctly before moving off and starting to lay material. Explain ‘Nulling’ the screed and setting the A of A A nulled screed simply means that there is some rotary movement in the depth crank when the screed is relaxed on the reference. Null the screed by turning the depth cranks CW until the screed rests on the blocks and the cranks become loose. Turn cranks CCW approximately two turns to raise the front of the screed and set the angle of attack ready for laying.

Starting Blocks Blocks are placed at each side of screed to assure equal depth across screed

End Gate Adjustments Keep end gate flush & level When matching a joint Adjust Spring Loaded end gates down to sub base to get a crisp edge

Clean and Trim Joint as Paver Moves Off Pull off Large Stones Form Joint with Fine Material Do not Broadcast Large Stones on to Mat

Avoid Broadcasting Larger Stones Across Mat Bumping Back the Joint Bumped Material Increases Material Quantity Here Which May Increase Density When Rolled 1st Mat 2nd Mat Avoid Broadcasting Larger Stones Across Mat

Double Check for Parallel Mat and Compaction Factor Checking the Mat No Dip Here Check for Parallel Straight Edge 1st Mat (Cold) New Mat (Hot) Direction of Travel Double Check for Parallel Mat and Compaction Factor Ref: Joints pg. 6

MAKING GOOD TRANSVERSE JOINTS 1. Maintain full depth & slope at shutdown 2. Good wedge formation 3. Good wedge removal & joint preparation 4. Align paver & screed with previously laid mat 5. Heat screed properly 6. Use lathes under screed to allow for roll-down 7. Null out the screed 8. Fill auger box with correct head of material & set sensors 9. Begin paving at normal paving speed 10. Check & if necessary correct grade & slope Always:

Joint Construction LONGITUDINAL JOINTS

Most surfaces are laid between 12-14 ft wide Today, most roads must be kept open to traffic Roads are better laid in one pass (Paving in echelon) Wide screeds can be 40 to 50 ft wide

Joint Deterioration To This How do we get…... From This Slide 22

Types of Longitudinal Joints Notched Wedge Joint Wedge Joint Cut Back Joint Standard or Tapered Joint

Use of Disc Cutter to Form a Clean Edge Cut Back Joint Use of Disc Cutter to Form a Clean Edge

Cut Away Edge to be Discarded The Cut Back Joint 1st Mat Cutting Disc Attached to Edge Compactor on Roller Cut Away Edge to be Discarded 1st Mat 1st Mat 2nd Mat Ref: Joints pg. 8

Notched Wedge Joint

Contractor Designed Notched Tapered Joint Maker

Notched Wedge Joint Maker and Roller

Always Check Joint Roll Down Behind Rollers for Guidance Correct Overlap 1/2 - 1 1/2 inches (13 - 35mm) Minimum Required Overlap for Compaction is 1/2 inch 13mm Always Check Joint Roll Down Behind Rollers for Guidance

Causes Bridging Here with Less Compaction Screed Supported by 1st Mat Screed 1st Mat 2nd Mat Limited Density Achieved Excessive Overlap Onto 1st Mat

Avoid Broadcasting Larger Stones Across Mat Bumping Back the Joint Bumped Material Increases Material Quantity Here Which May Increase Density When Rolled 1st Mat 2nd Mat Avoid Broadcasting Larger Stones Across Mat

Controlled Steering is a Must Longitudinal Joints Need a Good Edge to Follow

“Hot” Joint Construction Keep roller off edge of previous pass 6” to 8” Set end gate flush with screed extension & completely flat spray end gate frequently Overlap previous pass ¾” to1” Max Adjust up or down with manual or electric screw Use Automatic Joint Matcher

Always: 1. Steer a straight line 2. Adjust screed for proper overlap MAKING GOOD LONGITUDINAL JOINTS Always: 1. Steer a straight line 2. Adjust screed for proper overlap 3. Lay correct depth to allow for compaction 4. Strive to minimize segregation at joint edge 5. Prepare the joint well for rolling 6. Do not broadcast loose stones onto fresh surface mat 7. Use best rolling procedures

Use a lift thickness that is at least 4 times the NMAS for coarse gradations and 3 times the NMAS for fine gradations. Consider use of the notch wedge joint (versus butt) for lift thicknesses equal to or between 1 and 3 inches. Consider the use of infrared joint heaters, especially in cold weather paving. Use the smallest NMAS mix that is appropriate for the application. This will aid in obtaining the necessary density and also a more impermeable surface. Smaller size mixes are less permeable at a given in-place air void level.

Infrared Asphalt Joint Heater Paver Mounted

Infrared Joint Heater trailer Mounted

Joint Compaction

Compaction Goals Maintain the Grade, Slope & Profile left by the Paver Apply the fewest passes of the rollers necessary to get compaction Apply the lowest amount of compactive effort to get the job done Understanding the Compaction Curve Slide 42

Edge Rolling Unconfined Edge Confined Edge Min 6” Roller Drum

Alternative Unconfined Edge Edge Rolling Min 6” Alternative Unconfined Edge Roller Drum First Pass Rolling Technique to obtain density at Unconfined Edge

Rolling a Longitudinal Joint... First Alternative

Rolling the Longitudinal Joint Roller Drum Overlap Joint 6 inches “Vibration On” Cold Side 1st Lane Hot Side 2nd Lane

Rolling a Longitudinal Joint… Second Alternative

Rolling a Longitudinal Joint Roller Drum Vibration On 4 - 6 inches COLD HOT Note: Requires two vibratory passes.

Overlap 2nd Pass Roller Drum 6 ” Min. Overlap 2nd Pass 1st Pass

Rolling a Crown Overlap drum 3 - 6 inches over the crown. Roller Drum Note: Roll from the low to high side of the crown Never roll directly on top of the crown

It’s All Up to You! Quality Paving Joints Must be Your Goal! Slide 51