Agenda: Paver Operations - apa-mi.org

1 1. Principles of the Free Floating Screed1. Principles of the Free Floating Screed Forces Acting on the ScreedForces Acting on the Screed Issues Affecting the Forces that Impacts Smoothness & DensityIssues Affecting the Forces that Impacts Smoothness & Density2. Screed Adjustments Impacting Angle of Attack2. Screed Adjustments Impacting Angle of Attack Extension screed, Strikeoff, tow point positionExtension screed, Strikeoff, tow point position Pulling off The JointPulling off The Joint33. Segregation. Segregation Typical Locations, Causes & SolutionsTypical Locations, Causes & SolutionsMichigan 56th Annual Asphalt Paving ConferenceMichigan 56th Annual Asphalt Paving ConferenceAgenda: Paver OperationsAgenda: Paver OperationsWhat does it take to pave durable, longWhat does it take to pave durable, long--lasting, smooth , smooth Main ScreedScreedMat ThicknessMat ThicknessExtrusion Compaction Extrusion Compaction -- Due to Bull NoseDue to Bull NoseScreed Vibration CompactionScreed Vibration CompactionGradient CompactionGradient Compaction-- Due to Angle of attackDue to Angle of attackConventional Screed Compaction:Conventional Screed Compaction:1.

2 Extrusion Compaction 1. Extrusion Compaction -- Due to Bull nose on screed plateDue to Bull nose on screed plate2. Gradient Compaction 2. Gradient Compaction -- Due to screed angle of attack Due to screed angle of attack 3. Vibration Compaction 3. Vibration Compaction -- Due to screed vibration systemDue to screed vibration systemMax Compaction at Max Compaction at trailing edgetrailing edge0 Compaction at Leading Edge0 Compaction at Leading EdgePrinciples of the Free Floating ScreedPrinciples of the Free Floating ScreedOccurs at the Bull NoseOccurs at the Bull NoseInfluence by:Influence by:1. Main Strikeoff Adjustment1. Main Strikeoff AdjustmentOccurs along the flat of the plateOccurs along the flat of the plateDue to Angle of attackDue to Angle of attackInfluenced by the following:Influenced by the following:1.

3 Screed weight 1. Screed weight By design By design 2. Head of material2. Head of material3. Tow point position3. Tow point position4. Extension screed Angle of attack4. Extension screed Angle of attack5. Extension screed Match Height5. Extension screed Match HeightVibration CompactionVibration CompactionInfluenced by the following:Influenced by the following:1. Frequency1. Frequency2. Amplitude 2. Amplitude By design By design ExtrusionExtrusionCompactionCompactionGr adientGradientCompactionCompactionVibrat ionVibrationCompactionCompactionConventi onal Screed Compaction Conventional Screed Compaction For a given Mix design:For a given Mix design:Principles of the Free Floating ScreedPrinciples of the Free Floating ScreedCCTTMMFSFSR eview of Key Components of the Paver / Paving:Review of Key Components of the Paver / Paving:Principles of the Free Floating ScreedPrinciples of the Free Floating ScreedReview of Key Components of the Paver :Review of Key Components of the Paver .

4 Tow ArmTow Arm(Leveling Arm)(Leveling Arm)Tow PointTow Point(Pull Point)(Pull Point)TractorTractorMat DepthMat DepthThickness Thickness control Screwcontrol ScrewEquilibriumEquilibriumAngle of AttackAngle of Attack(5 Forces in Balance)(5 Forces in Balance)Pivot PointPivot PointTow PointTow PointCylinderCylinderScreedScreedScreed ArmScreed ArmPrinciples of the Free Floating ScreedPrinciples of the Free Floating ScreedIncrease or Decrease Mat Depth At Balance / EquilibriumIncrease or Decrease Mat Depth At Balance / EquilibriumMat Depth is Increase or Decrease by Changing the Screed Angle Mat Depth is Increase or Decrease by Changing the Screed Angle -- (Angle of Attack)(Angle of Attack)1. Manually By using the Thickness Control Screw1.

5 Manually By using the Thickness Control Screw2. Manually By using the Tow Point Jog Switch2. Manually By using the Tow Point Jog Switch3. Or Automatically using Grade & Slope Control Systems3. Or Automatically using Grade & Slope Control SystemsDecrease Angle Decrease Angle -- Decrease Mat DepthDecrease Mat DepthIncrease Angle Increase Angle -- Increase Mat DepthIncrease Mat DepthPrinciples of the Free Floating ScreedPrinciples of the Free Floating Screed5 tow arm length for 100% reaction to a change in angle of Attac5 tow arm length for 100% reaction to a change in angle of Attackk1 1 stst. Tow arm length . Tow arm length Approx 65%Approx 65%2 2 ndnd1st1st3 rd3 rd4 4 thth5 5 thth65 %65 %85 %85 %100 %100 %Principles of the Free Floating ScreedPrinciples of the Free Floating ScreedMake a change and wait for the screed to respondMake a change and wait for the screed to respondFor quick response For quick response Over correct and monitorOver correct and monitorPrinciples of the Free Floating ScreedPrinciples of the Free Floating ScreedAllow the screed to react before checking Mat DepthAllow the screed to react before checking Mat DepthPrinciples of the Free Floating ScreedPrinciples of the Free Floating ScreedFree Floating ScreedFree Floating ScreedPrinciples of the Free Floating

6 ScreedPrinciples of the Free Floating ScreedAveraging Ski: Mechanical Drag BeamAveraging Ski: Mechanical Drag BeamSingle Sensor referencing off a Drag BeamSingle Sensor referencing off a Drag Beam3030 to 40to 40 Beam flexes to average the Grade ContourBeam flexes to average the Grade ContourPrinciples of the Free Floating ScreedPrinciples of the Free Floating ScreedAveraging Ski: Non Contact BeamAveraging Ski: Non Contact Beam3 to 4 Sensor referencing off the Grade / Contour3 to 4 Sensor referencing off the Grade / Contour3030 --5050 Beam availableBeam availableAt EquilibriumAt Equilibrium::All Forces are in BalanceAll Forces are in BalanceConstant Mat Depth is MaintainedConstant Mat Depth is MaintainedThe screed is free floating with an The screed is free floating with an Equilibrium Angle (Angle of Attack)Equilibrium Angle (Angle of Attack)

7 Change in any of the 5 Force cause the Change in any of the 5 Force cause the screed to Rise or Fallscreed to Rise or Fall5 Forces acting on the screed to Hold Mat Depth5 Forces acting on the screed to Hold Mat Depth-- For a Given Tow Point Position & Screed AdjustmentFor a Given Tow Point Position & Screed Adjustment-- NOT by any Mechanical or Hydraulic DeviseNOT by any Mechanical or Hydraulic DevisePrinciples of the Free Floating ScreedPrinciples of the Free Floating ScreedIssues Affecting the Forces:Issues Affecting the Forces:a) Pull Force (P) a) Pull Force (P) Maintain a constant Speed as PossibleMaintain a constant Speed as Possible Speeding up & Slowing Down Speeding up & Slowing Down --Disrupt the Equilibrium of ForcesDisrupt the Equilibrium of Forces Changes Resistance of the screed against the head of MaterialChanges Resistance of the screed against the head of Material Resulting in Change in mat thickness / Rough RideResulting in Change in mat thickness / Rough RideSpeed Speed Dial & DisplayDial & DisplayPrinciples of the Free Floating ScreedPrinciples of the Free Floating ScreedIssues Affecting the Forces:Issues Affecting the Forces.

8 A) Pull Force (P)a) Pull Force (P)Maintain a Constant Paving Speed as possibleMaintain a Constant Paving Speed as possible Plan the JobPlan the Job Paving Speed should be based on:Paving Speed should be based on: Material delivery Material delivery Rolling CapabilitiesRolling Capabilities Tonnage delivered = Tonnage Laid Tonnage delivered = Tonnage Laid Tonnage Laid = Paving Speed X Mat Width X Mat Thickness Tonnage Laid = Paving Speed X Mat Width X Mat Thickness Several charts available to assist in Calculation Several charts available to assist in Calculation Principles of the Free Floating ScreedPrinciples of the Free Floating ScreedIssues Affecting the Forces:Issues Affecting the Forces:Effect of Stopping and StartingEffect of Stopping and StartingSettling Dents & HumpsSettling Dents & HumpsAlso be impacted by:Also be impacted by:1.

9 Automation Engaged When Stopped1. Automation Engaged When Stopped2. Vibration Engaged when Stopped2. Vibration Engaged when Stopped3. Material cooling3. Material coolingPrinciples of the Free Floating ScreedPrinciples of the Free Floating ScreedIssues Affecting the Forces:Issues Affecting the Forces:Reducing Settling & HumpsReducing Settling & Humps-- Use Screed Hold & Freeze when Available to Reduce Settling & HUse Screed Hold & Freeze when Available to Reduce Settling & Humpsumps-- Operators Operators -- Disengage Neutral Lock and Start Moving Instantly Disengage Neutral Lock and Start Moving Instantly Principles of the Free Floating ScreedPrinciples of the Free Floating ScreedIssues Affecting the Forces:Issues Affecting the Forces.

10 Effect of Stopping and StartingEffect of Stopping and StartingSettling Dents & Humps Significantly impact SmoothnessSettling Dents & Humps Significantly impact SmoothnessIRI IRI -- International Ride Index (Inches / Mile)International Ride Index (Inches / Mile)Principles of the Free Floating ScreedPrinciples of the Free Floating ScreedMTV MTV Non Contact Continuous PavingNon Contact Continuous PavingPrinciples of the Free Floating ScreedPrinciples of the Free Floating ScreedIssues Affecting the Forces:Issues Affecting the Forces:a) Pull Force (P)a) Pull Force (P)Always ensure straight steering & smooth turnsAlways ensure straight steering & smooth turnsEnsures the screed is maintaining Consistent gradeEnsures the screed is maintaining Consistent gradeUse steering guides or Auto Turning Radius if AvailableUse steering guides or Auto Turning Radius if AvailableAutomatic Automatic Turning / Turning / RadiusRadiusPrinciples of the Free Floating ScreedPrinciples of the Free Floating ScreedIssues Affecting the Forces:Issues Affecting the Forces.