Booklet on Paving

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1 Design of a Road Paver 4 1.1 Components of a Road Paver. . . 6 2 Machinery / Applications 8 2.1 Differences in Construction Machinery‘s Methods of Profiling Surfaces . . . 10 2.2 The Floating Screed . . . 11 2.3 Theoretical Outline of the Floating Screed Principle without Control System . . . 12 2.4 Control of the Floating Screed . . . 13 2.5 Tracked Pavers and Wheeled Pavers . . . 14 2.5.1 Examples of Paver Applications . . . 16 2.6 Pavers and Performances . . . 18 2.6.1 Tracked Pavers . . . 18 2.6.2 Special Equipment . . . 22 2.6.3 Wheeled Pavers . . . 24 3 Material Feed and Material Handling 26 3.1 Feed of Paver with Mix. . . 28 3.2 Conveyance of Mix (Longitudinal Direction) . . . 30 3.3 Spreading of Mix (Transverse Direction) . . . 31 3.4 Distance Between Tractor Unit and Screed . . . 32 4 Screed 34 4.1 Function Fulfilled by the Screed . . . 36 4.2 Extending Screeds . . . 38 4.2.1 Compacting Systems Installed in Extending Screeds . . . 40 4.2.2 Extending Screeds and Bolt-on Extensions . . . 42 4.2.3 Set-Up of the Extending Screed . . . 44 4.3 Fixed-Width Screeds . . . 46 4.3.1 Options for Fixed-Width Screeds and Special Concrete Screed . . . 47 4.3.2 Compacting Systems Installed in Fixed-Width Screeds . . . 48 4.3.3 Fixed-Width Screeds and Bolt-on Extensions . . . 50 4.3.4 Building Up a Fixed-Width Screed with Bolt-on Extensions . . . 54 4.4 Screeds at a Glance . . . 56 4.5 Set-Up of Tamper . . . 58

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5.2 Paving Parameters. . . 67 5.3 Paver Set-Up . . . 67 5.4 Relationship Between Tamper Speed and Pave Speed . . . 70 5.5 Recommended Settings for the Compacting Systems . . . 71 5.6 Functions of the Hydraulic Rams for Raising / Lowering the Screed . . . 72 6 Recommendations for Paving / Points to Note 74 6.1 Basic Principles . . . 76 6.1.1 Setting the Layer Thickness . . . 78 6.1.2 Weather Conditions when Paving Asphalt . . . 80 6.1.3 Requirements Made on the Base and Sub-Base . . . 81 6.2 Augers and Limiting Plates for the Auger Tunnel on an Extending Screed . . . 84 6.3 Head of Mix in Front of the Screed. . . 86 6.4 Definition of the Route . . . 87 6.5 Correct Use of NIVELTRONIC® _{. . . 88} 6.5.1 Automated Grade and Slope Control . . . 88 6.5.2 Development from NIVELTRONIC®_{to NIVELTRONIC Plus}®_{. . . 89}

6.5.3 Quick Reference Guide for NIVELTRONIC®_{and NIVELTRONIC}®_/ V-TRONIC®_{. . . 90}

6.5.4 Quick Reference Guide for NIVELTRONIC Plus®_{. . . 93} 6.5.5 Components of NIVELTRONIC® _{. . . 96} 6.5.6 Use of Different Grade Sensors . . . 100 6.6 Position of Sensors for Control of the Floating Screed (Example: Referencing from Stringline) . . . 104 6.7 Position of the Grade Sensor in Transverse Direction . . . 105 6.8 Use of Screed Assist . . . 106 6.9 Joints between Lanes . . . 108 6.9.1 Paving “Hot to Cold” . . . 108 6.9.2 Paving “Hot to Hot” . . . 109 6.10 Joints in Asphalt Pavements . . . 110 6.11 Expansion Joints . . . 113 7 Imperfect Paving 114 7.1 Paving Problems / Paving Errors . . . 116 7.1.1 Irregularities when Passing Over Mix . . . 116 7.1.2 Pavement Irregularities due to Large Screed Planing Angle . . . 117 7.1.3 Buldge Formed when Resuming Paving . . . 118 7.1.4 Short Irregularities in Transverse Direction . . . 119 7.1.5 Periodic Irregularities in Longitudinal Direction . . . 120 7.2.3 Strips in the Lateral Areas of the Pavement . . . 126 7.2.4 Patches of Mix in the Surface Texture. . . 127 7.3 Imprints. . . 128 7.4 Longitudinal Step . . . 128 7.5 Non-Uniform Surface Structure due to Crushed Grains . . . 129 8 Basics for Calculation 130 8.1 Quantity of Mix. . . 132 8.2 Laydown Rate . . . 133 9 Paving Materials 134 9.1 General Pavement Structure . . . 136 9.2 Producing Asphalt Mix . . . 140 9.3 Types of Pavement Layers. . . 144 9.4 Bitumen Grades Used . . . 145 9.5 Asphalt Types and their Compositions . . . 146 9.5.1 Stone Mastic Asphalt . . . 146 9.5.2 Asphaltic Concrete (Paved Hot) . . . 148 9.5.3 Asphaltic Binder . . . 150 9.5.4 Asphalt Base . . . 152 9.6 Mix Temperatures in °C. . . 154 9.7 Causes of Poor Quality of Asphaltic Concrete Mixes for Hot Paving . . . 155 10 Preparations for Paving Hot Mix 156 10.1 Choosing the Right Paver . . . 158 10.2 Preparing the Base for Paving . . . 160 10.3 Subsequent Compaction by Rolling . . . 160 10.3.1 Density Measurement . . . 160 10.3.2 Rules for Rolling . . . 161 11 Index / Notes 162

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1.1 Components of a Road Paver

1. Traction

In VÖGELE road pavers, powerful engines are installed for a high tractive effort. VÖGELE pavers come in tracked or wheeled versions.

2. Material Hopper

Feed lorries dump the paving material into the material hopper at the front of the road paver.

3. Conveyors

Wide conveyors transfer the paving material from the material hopper through the conveyor tunnel inside the machine to the augers in front of the screed.

4. Augers

Augers fulfi l the task of evenly spreading the mix in front of the screed. Augers are

adjustable in width to match the width of the screed so that uniform compaction of the paving material is ensured at all times.

5. Screed

The screed is the core of the VÖGELE road paver. The screed acts upon the paving material by way of its own weight and the compactive effort of its compacting systems. This results in pre-compaction of the mix and profi ling of the placed layer.

6. Screed Heating

In order to prevent the asphalt mix from sticking to the screed plates and the compacting elements (tamper, vibrators, pressure bar(s)), electric heating is provided.

7. Adjustment of Screed Tow Points

VÖGELE pavers level out irregularities in the base by adjusting the screed tow points in height. This is done by way of hydraulic rams.

8. Screed Assist

Depending on the working conditions on site, pressure is applied to the hydraulic rams linked to the screed arms, or the hydraulic rams are relieved of pressure. This infl uences the weight of the screed (see pages 68, 72 and 73).

The Machines Made by VÖGELE

Road pavers place all kinds of bituminous materials. When the mix has been dumped into the paver’s material hopper by the feed lorry, conveyors transport the material in front of the screed. This is where the process of paving proper takes place. VÖGELE pavers stand out through their capability of producing high compaction, their excellent reliability as

well as service-friendliness and ease of maintenance.

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2.1 Differences in Construction Machinery‘s Methods of Profiling Surfaces . . . 10 2.2 The Floating Screed . . . 11 2.3 Theoretical Outline of the Floating Screed Principle without Control System. . . 12 2.4 Control of the Floating Screed . . . 13 2.5 Tracked Pavers and Wheeled Pavers . . . 14 - 15 2.5.1 Examples of Paver Applications. . . 16 - 17 2.6 Pavers and Performances . . . 18 2.6.1 Tracked Pavers . . . 18 - 22 2.6.2 Special Equipment . . . 22 - 23 2.6.3 Wheeled Pavers . . . 24 - 25

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2.2 The Floating Screed

The “floating“ working tool is the main difference distinguishing a road paver

from other construction machinery. In other words, the layer thickness only changes

as a result of changes in the screed‘s planing angle or changes in the height

of the screed tow points. This way, irregularities in the ground, when passed over,

are diminished without having to intervene through a control system.

Short irregularities in the base are levelled out through the self-levelling property of the Floating Screed.

When passing over long irregularities, the height of the screed tow points changes, thus leading to a change in the layer thickness.

Depending on the screed planing angle, more or less mix is packed under the screed as the paver advances, and the layer thickness gradually changes over a longer distance.

Bulldozer

The working tool (blade) is firmly linked to the chassis via hydraulic rams. When passing over irregularities in the ground, these are transmitted to the blade to a greater extent, unless counteracted.

Lift of Blade

2.1 Differences in Construction Machinery‘s Methods

of Profiling Surfaces

The response of the screed to such changes depends on:

- Pave speed

- Change in height of the screed tow points - Properties of the mix (compactability,

load bearing capacity).

Height of Screed Tow Point

Speed Properties of Mix

Grader

The working tool (blade) is firmly linked to the chassis via hydraulic rams. When passing over irregularities in the ground, these are transmitted to the blade to a lesser extent, unless counteracted.

Lift of Blade

Road Paver

The working tool is not firmly linked to the chassis. The screed is carried by the mix (principle of the Floating Screed) and changes its position only as a result of changes in the screed planing angle. The screed moves up and down to a lesser extent than the actual irregularity.

Change in Screed Planing Angle

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4

H b h

a

2.4 Control of the Floating Screed

As the layer thickness needs not necessarily be constant over the entire section

to be paved, the screed can be controlled while paving.

The following rule can be derived from the example of a paver passing over a short irregularity:

Taking into account different lengths (b) (extending over length of screed arm and depth of screed plate) for the different paver types, an average ratio of about 5 : 1 results as far as compensation of a short irregularity in the base is concerned.

Long irregularities in the base can only be levelled out by actively controlling the height of the screed tow points.

2.3 Theoretical Outline of the Floating Screed Principle

without Control System

Please Note

The evenness of the pavement must increase with every layer placed.

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6 h =

H x a

b

h = Height after compensation H = Height of irregularity a = Depth of screed plate b = Length of screed arm + depth of screed plate 7. Hydraulic Rams for Raising / Lowering the Screed

These hydraulic rams primarily serve to lift the screed. They move up and down freely in Screed Float mode. The rams can also be actively operated in special paving situations.

6. The Screed Operator‘s Console

The screed operator can adjust the position of the hydraulic rams for tow point control from his lateral console.

5. Scale for Layer Thickness

The scale indicates the current position of the screed tow points to the paver and screed operators.

2. Screed Arm

The screed arm serves as a lever for converting a vertical change (up or down) of the screed‘s tow points into a change in the screed’s planing angle. It also levels out irregularities in the base.

1. Screed Planing Angle

The layer thickness can be changed by changing the planing angle of the screed.

3. Screed Tow Points

While paving, the screed is controlled by adjusting the screed tow points up or down.

4. Hydraulic Rams for Tow Point Control

The hydraulic rams serve to adjust the height of the screed tow points.

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2.5 Tracked Pavers and Wheeled Pavers

VÖGELE pavers are available in tracked or wheeled versions. Each version offers

its particular advantages.

ADVANTAGES OF THE TRACKED PAVER ■ High tractive effort.

■ Universal application.

■ Handles large pave widths.

■ Easily pushes heavy feed lorries.

■ Use also on a soft base.

ADVANTAGES OF THE WHEELED PAVER ■ Travel from one job to another

under its own power. Travel speed up to 20km/h also on public roads.

■ Ideal when frequent and quick transfer is required.

■ Smooth running when paving asphalt wearing course.

■ Excellent manœuvrability.

■ Front wheels are in permanent contact with the ground thanks to oscillating axle.

Tracked Paver

Crawler tracks transmit the power delivered by the high-performance engine to the ground. In contrast to wheels, crawler tracks have a larger contact area with the base, allowing them to achieve a higher tractive effort. For the tracked pavers, the power is generated where it is needed: right at the sprocket. The powerful undercarriage is ideal for use of the paver also on diffi cult terrain and in large pave widths up to 16m.

For the two crawler tracks, separate electronic control is provided. This allows impeccable turning also of radii at a constant pave speed.

Wheeled Paver

Wheeled pavers display their strong points above all when it comes to frequent travels from one project to another. VÖGELE pavers travel at speeds up to 20km/h under their own power, so no trucking required for job sites in the near surroundings. The wheeled VÖGELE pavers feature excellent manoeuvrability thanks to a turning radius of just 6.5m.

For placing high-quality surface course, smooth running of the paver is a must. The wheeled VÖGELE pavers optimally achieve this goal thanks to the damping effect of their rear wheels.

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Classical Application

Placing all kinds of pavement layers for roadways and paths. Pavers are available in various performance classes and combine with a variety of screed options to handle these paving jobs. Layer thickness ranges from 2cm to 40cm.

2.5.1 Examples of Paver Applications

Paving on a Slope (Vertical)

Apart from construction of conventional roads with gradients (uphill or downhill), road pavers can also be used for special applications, such as paving on a slope for construction of dams, retaining walls, etc. In general, only slight conversion of the paver is required for handling this kind of jobs.

For application under extreme conditions (steep slope), a special Slope Paver can be used that has undergone modification.

Paving on a Slope (Horizontal)

As an alternative to paving in a vertical direction, pavers also work in a horizontal direction. In general, such applications, too, require no more than slight conversion of the paver. Paving work like this is also often found in the field of dam or canal construction.

Paving Asphalt Tracks or Special Profiles

Extending Screeds can be set up for paving a large variety of special profiles thanks to their systems for adjustment. Special slipforms are available for paving farm tracks. Furthermore, the screeds are suited to placing track beds for railway routes or building parabolic profiles for racing circuits, to mention just a few examples.

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Tracked Paver SUPER 600

Maximum Pave Width 2.7m

Maximum Laydown Rate 200 tonnes/h

Engine Output 45kW

Rpm (according to DIN) 2,300

Weight 5.3 tonnes

Fuel Tank 75 Iitres

Pave Speed 1 30m/min.

Material Hopper 5 tonnes

Tracked Paver SUPER 1100-2

Engine Output 58kW

Weight 8.5 tonnes

Fuel Tank 120 Iitres

Maximum Pave Speed 30m/min.

Maximum Travel Speed 3.6km/h

Engine Output 45kW

Weight 6.1 tonnes

Fuel Tank 75 Iitres

Tracked Paver SUPER 800

Maximum Pave Width 5m

Engine Output 74.9kW

Weight 9.5 tonnes

Tracked Paver SUPER 1300-2

2.6 Pavers and Performances

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Tracked Paver SUPER 1600-2

Engine Output 100kW

Weight (depending on screed) 18.4 tonnes

Tracked Paver SUPER 1800-2

Tracked Paver SUPER 1900-2

Engine Output 142kW

Maximum Laydown Rate 1,100 tonnes/h

Engine Output 182kW

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Tracked Paver SUPER 2500

Engine Output 273kW

Material Hopper 17.5 tonnes

2.6.2 Special Equipment

SUPER 2100-2 IP for Paving Binder Course

Engine Output 182kW

Weight* 26.6 tonnes

*without extra material hopper

Conveying Capacity 900 tonnes/h*

Feed Height (hopper bottom) 625mm

Engine Output 112kW

Weight

Mobile Feeder 16 tonnes

Weight

Receiving Hopper up to 2 tonnes

Maximum Operating Speed 16m/min.

*dependent on type of mix

MT 1000-1 Mobile Feeder

Weight* 20.8 tonnes

*with screed, SprayJet Module without emulsion

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2.6.3 Wheeled Pavers

Engine Output 58kW

Weight 8.6 tonnes

Maximum Travel Speed 20km/h

Wheeled Paver SUPER 1103-2

Weight 9.5 tonnes

Wheeled Paver SUPER 1303-2

Engine Output 100kW

Weight (depending on screed) 17 tonnes

Wheeled Paver SUPER 1603-2

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3.1 Feed of Paver with Mix . . . 28 - 29 3.2 Conveyance of Mix (Longitudinal Direction) . . . 30 3.3 Spreading of Mix (Transverse Direction) . . . 31 3.4 Distance Between Tractor Unit and Screed . . . 32 - 33

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3.1 Feed of Paver with Mix

The feed truck reverses up to the paver and stops a few centimetres in front of it. If it were to hit the paver‘s push-rollers, the screed’s trailing edge might leave a trace in the pavement.

As the paver approaches, its push-rollers touch the rear wheels of the truck, which is then pushed by the paver.

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3.2 Conveyance of Mix (Longitudinal Direction)

3.3 Spreading of Mix (Transverse Direction)

The mix is evenly spread in front of the screed by two separately controlled rotating augers located between tractor unit and screed. Extensions can be fitted to the auger shafts so that the spread width can be optimally adapted to the pave width. The rotational speed of the auger is controlled by sensors in proportion with the head of mix in front of the screed. This permits optimal adjustment to match the requirement for mix when turning a radius or when paving layers of varying thickness. In extreme cases, auger rotation can be reversed so that the mix is moved from the outside inwards.

Tip!

The auger shaft should reach up to 20cm within the end plate. This promotes a continuous flow of mix.

Spreading Direction

The truck reverses up to the paver and tips the mix into the paver‘s material hopper. From there, it is transported through the machine by two separately controlled conveyors, ascending slightly towards the rear. As a result of the higher dumping point, thicker pavement layers can be placed and the mix is delivered onto the augers instead of being pressed into them.

The conveyor speed is controlled in proportion with the level of mix in the auger tunnel. When moving the paver on site, mix can be returned to the material hopper by briefly reversing the conveyor movement.

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“Normal“ Screed Position

For all standard mixes and a layer thickness between 3cm and 25cm.

3.4 Distance Between Tractor Unit and Screed

In order to allow high-quality paving of most varied layer thicknesses and different

paving materials, the screed’s position can be varied.

Larger distance between augers and screed. This helps avoid any segregation of mix that might occur.

When laying a mix of poor bearing capacity in thick layers, the screed tow point rams may not be able to set the screed to the required screed planing angle.

In this case, the screed arm can be changed in position to permit a large planing angle even when paving thick layers.

This set-up is recommended when paving a mix of poor bearing capacity in thick layers. The larger auger tunnel prevents the auger drawing the mix away from under the screed.

Attention!

Higher tractive effort required when distance between augers and screed is larger.

Attention!

A higher tractive effort is required as a result of the larger head of mix in front of the screed.

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4.1 Function Fulfilled by the Screed . . . 36 - 37 4.2 Extending Screeds . . . 38 - 39 4.2.1 Compacting Systems Installed in Extending Screeds . . . 40 - 41 4.2.2 Extending Screeds and Bolt-on Extensions . . . 42 - 43 4.2.3 Set-Up of the Extending Screed . . . 44 - 45 4.3 Fixed-Width Screeds . . . 46 4.3.1 Options for Fixed-Width Screeds and Special Concrete Screed . . . 47 4.3.2 Compacting Systems Installed in Fixed-Width Screeds . . . 48 - 49 4.3.3 Fixed-Width Screeds and Bolt-on Extensions . . . 50 - 53 4.3.4 Building Up a Fixed-Width Screed with Bolt-on Extensions . . . 54 - 55 4.4 Screeds at a Glance . . . 56 - 57 4.5 Set-Up of Tamper . . . 58 4.6 Set-Up of Tamper Shield . . . 59 4.7 Set-Up of Pressure Bar(s). . . 60 4.8 Bevel Irons . . . 61 4.9 Function Check of Screed Heating. . . 62 - 63

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4.1 Function Fulfi lled by the Screed

The screed, the road paver‘s working tool, fulfi ls the function of uniformly compacting the paving material across the entire pave width and producing a close-textured and level surface. The screed‘s compacting systems shall pre-compact the mix to the greatest possible extent. This is to minimize the infl uence of layer thickness upon the amount of subsequent compaction by rolling when bringing about the pavement’s fi nal density. For pre-compaction, different compacting systems are available:

T = Tamper (an eccentric shaft causes the tamper bar to

move up and down)

V = Vibrators (vibrations are generated by an eccentric

shaft acting on the screed plates at right angles to the direction of motion)

P = Pressure Bar(s) (the pressure bar(s) are hydraulically

pressed onto the mix at a frequency of 68 Hz (approx.) and a maximum pressure of 130 bar)

P1 = Screed equipped with 1 Pressure Bar P2 = Screed equipped with 2 Pressure Bars Screed Technology

The screed is the true heart of the VÖGELE paving system. It accommodates the compacting systems which provide high density

and durable results. VÖGELE screeds are available in two versions: as Fixed-Width Screeds (SB) or Extending Screeds (AB).

Hydraulic Ram for Screed Width Control Sliding Restraint System Single-Tube Telescoping System Tamper with Heating Rod Pressure Bars with Heating Rods Screed Plate with Heating Element Screed’s Hydraulically Extending Unit Screed Body Design of the VÖGELE Extending Screed

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4.2 Extending Screeds

Screed Versions V, TV

Basic Width 1.1m

Larger Widths V/TV: 35cm to 2.7m

with Bolt-on Extensions TV: 60cm to 3.2m

Reduction in Width

Infinitely Variable Range 0.5m to 1m

Crown Adjustment (Mechanical) -2% to +4% Weights V: 600 kg (Basic Screed) TV: 720 kg

AB 200 Extending Screed

AB 340 Extending Screed

AB 500-2 Extending Screed

AB 600-2 Extending Screed

AB 200 V (with vibrators) has been specially designed for use with SUPER 600. AB 200 TV (with tamper and vibrators) combines with SUPER 800.

Screed Versions V, TV

Basic Width 1.8m

Larger Widths V/TV: 40cm to 4.2m

with Bolt-on Extensions TV: 55cm to 4.5m _{TV: 80cm to 5m} Reduction in Width

with Cut-Off Shoes 52.5cm

Crown Adjustment

(Mechanical) -2.5% to +4.5%

Weights V: 1.3 tonnes

(Basic Screed) TV: 1.4 tonnes

The AB 340 Extending Screed is the perfect match for the compact pavers in the SUPER 1100 and SUPER 1300 classes. Like all VÖGELE screeds, it comes with a powerful screed heating system.

Screed Versions TV, TP1, TP2

Basic Width 2.55m

Maximum Pave Width 8.5m*

Larger Widths 25cm, 75cm,

with Bolt-on Extensions 125cm

Reduction in Width

Crown Adjustment

(Mechanical1₎ -2.5% to +5%*

Weights TV: 3.2 tonnes

(Basic Screed) TP1: 3.45 tonnes _{TP2: 3.8 tonnes}

*dependent on type of tractor unit 1 _{hydraulic (option)}

AB 500-2 combines with all VÖGELE tractor units featuring a basic width of 2.5m. The screed extends hydraulically from 2.55m to 5m, so that pave widths within this range can be handled without a need to fit bolt-on extensions.

AB 600-2 is ideally suited for combination with VÖGELE pavers in the upper mid-range and also with SUPER 2500 (basic width 3m).

Screed Versions TV, TP1, TP2

Basic Width 3m

with Bolt-on Extensions 125cm

Reduction in Width

Crown Adjustment

(Mechanical1₎ -2.5% to +5%*

(Basic Screed) TP1: 3.95 tonnes _{TP2: 4.3 tonnes}

*dependent on type of tractor unit 1 _{hydraulic (Option)}

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4.2.1 Compacting Systems Installed in Extending Screeds

V = Vibrators Installed in: - AB 200 - AB 340 Recommended for:

- Materials which are easy to compact.

TV = Tamper and Vibrators Installed in: - AB 200 - AB 340 - AB 500-2 - AB 600-2 Recommended for: - All conventional mixes.

- Use with wheeled pavers due to the lower weight as compared to screeds in TP1 or TP2 versions. - Materials which are easy to compact.

TP1 = Tamper and 1 Pressure Bar

Installed in: - AB 500-2 - AB 600-2

Recommended for: - All conventional mixes.

- Pre-compaction by a screed in TP1 version is higher than by a TV screed, but lower than by a screed in TP2 version.

- Less extra compaction by rolling required.

TP2 = Tamper and 2 Pressure Bars

Installed in: - AB 500-2 - AB 600-2

- The screed in TP2 version achieves a high pre-compaction when placing thick layers. - Mixes which are difficult to compact on account

of their grain shapes and consistency. - Less extra compaction by rolling required. - Jobs which do not allow subsequent compaction

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4.2.2 Extending Screeds and Bolt-on Extensions

For all VÖGELE screeds, bolt-on extensions are available. The VÖGELE system of bolt-on extensions allows to easily and sturdily build up screeds to any pave width desired. Even when paving in large widths, VÖGELE screeds work with highest precision and achieve superb degrees of uniform density right up to the pavement edges. When fitting bolt-on extensions, care must be taken to ensure that the bottom edge of the screed plate is flush with the adjacent units, otherwise a step may be produced in the pavement or the screed planning angle may change. During the paving process, this can have a negative effect on pre-compaction, surface structure and floating behaviour of the screed.

AB 500-2 AB 600-2 1.225m 2.55m 1.225m 5m 2 x 0.25m 5.5m 2 x 0.75m 6.5m 2 x 0.75m + 2 x 0.25m 7m 2 x 1.25m 7.5m 4 x 0.75m 8m 4 x 0.75m + 2 x 0.25m 8.5m 1.5m 3m 6m 2 x 0.25m 6.5m 2 x 0.75m 7.5m 2 x 0.75m + 2 x 0.25m 8m 2 x 1.25m 8.5m 4 x 0.75m 9m 4 x 0.75m + 2 x 0.25m 9.5m 1.5m 3.4m 2 x 0.4m 4.2m 2 x 0.55m 4.5m 1.8m 0.8m 0.8m 2 x 0.8m 5m AB 200 AB 340 0.45m 1.1m 2m 2 x 0.35m 2.7m 2 x 0.6m 3.2m 0.45m

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4.2.3 Set-Up of the Extending Screed

1. Position both extending units in place so that the screed plate of the basic unit and the screed plates of the extending units are roughly level.

2. Slacken the chains connecting the spindles on the extending unit so that each spindle can be adjusted independently.

3. Carefully lower the screed onto the extending units. Timber should be placed under the middle of the two extending units.

4. Now adjust the screed planing angle via the tow point rams so that the screed plate rests on the timber. 5. Remove the locking screw from the

threaded bush on all spindles. 6. Adjust all threaded bushes. 7. Refit the locking screws.

8. Raise the screed and secure it so that it cannot sink.

9. Lay a ruler along the inner and outer spindle pairs and then adjust the height of the extending unit via the front and rear spindles with the aid of a special wrench, so that the screed plate of the basic unit is level with the trailing edge of the extending unit. Now adjust the planing angle of the extending unit via the front spindle.

10. Reconnect the spindle pairs with the chains.

11. Raise the frame of the extending unit by approx. 4mm so that it roughly corresponds to the planing angle of the screed.

12. During the first on-site job, the height of the extending units must be corrected until a longitudinal step is no longer visible.

Basic Unit 0.5mm Extending Unit Timber Spindles Basic Unit Extending Unit 0.5mm

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4.3 Fixed-Width Screeds

Screed Versions TV, TP1, TP2, TVP2

Basic Width 2.5m

with Bolt-on Extensions 100cm, 150cm

Reduction in Width

with Cut-Off Shoes 25cm, 50cm

Crown Adjustment

(Mechanical) -2% to +3%

(Basic Screed) TP1: 1.88 tonnes TP2: 2.02 tonnes TVP2: 2.1 tonnes

SB 250 Fixed-Width Screed

SB 300 Fixed-Width Screed

Hydraulic Bolt-on Extensions for SB 250 / SB 300 Fixed-Width Screeds

SB 250 B Concrete Screed

The SB 250 Fixed-Width Screed combines with a variety of VÖGELE tractor units. The screed allows tractor units with a basic width of 2.5m to make use of the advantages offered by VÖGELE Fixed-Width Screed Technology.

The SB 300 Fixed-Width Screed for SUPER 2500 covers a wide range of applications from a basic width of 3m through to a maximum width of 16m.

Fixed-Width Screeds are ideal for paving in larger widths. Their fields of applications are enhanced by VÖGELE Hydraulic Bolt-on Extensions.

For concrete paving, high compaction is a crucial issue. The SB 250 B Concrete Screed is ideally suited to PCC®_{paving on storage areas for}

containers, roads on factory grounds, industrial floors, etc.

Screed Version TVP2

Basic Width 2.5m

Crown Adjustment

(Mechanical) -2% to +3%*

* With SUPER 1900-2. Other pave widths or tractor units upon request.

Use of the SB 250 B Concrete Screed belongs to the field of special applications. Clients interested in this screed are requested to contact the VÖGELE Applications Technology Service.

4.3.1 Options for Fixed-Width Screeds and Special Concrete Screed

Screed Versions TV, TP1, TP2, TVP2

Basic Width 3m

Reduction in Width

with Cut-Off Shoes 25cm, 50cm

Crown Adjustment

(Mechanical) -2% to +3%

Weights TV: 2 tonnes

(Basic Screed) TP1: 2.26 tonnes TP2: 2.41 tonnes TVP2: 2.5 tonnes

Screed Versions T, TP1, TP2

Infinitely Variable Range, Each Side 75cm

Infinitely Variable Range, Total 1.5m

Weigths T: 1.55 tonnes

(1 Set) TP1: 1.7 tonnes _{TP2: 1.8 tonnes}

• To be mounted to 1m or 1.5m

fixed bolt-on extensions

• Basic screed needs to be

enlarged in width by at least 1.5m, left and right sides Mounting

(26)

4.3.2 Compacting Systems Installed in Fixed-Width Screeds

TP2 = Tamper and 2 Pressure Bars

Installed in:

- SB 250 (and Hydraulic Bolt-on Extensions) - SB 300 (and Hydraulic Bolt-on Extensions) Recommended for:

- All conventional mixes.

- A screed in TP2 version achieves a high pre-compaction even of thick pavement layers. - Mixes which are difficult to compact on account

of their grain shape and consistency. - Jobs where paving can be done in a largely

constant width. - Large radii.

- Less effort required for subsequent compaction by rolling. TVP2 = Tamper, Vibrators and 2 Pressure Bars Installed in: - SB 250 - SB 300 - SB 250 B Recommended for:

- Jobs where paving can be done in a largely constant pave width.

- Large radii.

- SB 250, SB 300: All conventional mixes.

- SB 250 B: For paving PCC®_{, as this type of job does}

not include subsequent compaction by rolling.

TV = Tamper and Vibrators

Installed in: - SB 250 - SB 300

- Materials which are easy to compact or thinner pavement layers.

- Jobs where paving can be done in a largely constant width.

- Large radii.

TP1 = Tamper and 1 Pressure Bar

Installed in:

- SB 250 (and Hydraulic Bolt-on Extensions) - SB 300 (and Hydraulic Bolt-on Extensions) Recommended for:

- All conventional mixes.

- Pre-compaction by a screed in TP1 version is higher than by a TV screed, but lower than by a screed in TP2 version.

- Jobs where paving can be done in a largely constant width.

- Large radii.

- Less effort required for subsequent compaction by rolling.

(27)

4

Top View Horizontal Bracing

4.3.3 Fixed-Width Screeds and Bolt-on Extensions

As a general rule, bolt-on extensions should be fitted symmetrically on both sides of the screed, wherever possible. The advantage of a Fixed-Width Screed is a deeper screed plate of 500mm compared to a screed plate of 250mm found on Extending Screeds. This has a positive effect upon the screed‘s floating behaviour.

Moreover, the leading edge of the Fixed-Width Screed forms a single line over the entire pave width and different planing angles do not leave marks in the pavement. Fixed-Width Screeds are capable of handling considerably larger pave widths than Extending Screeds, albeit with restrictions as regards the screed‘s variability. As a result, Fixed-Width Screeds are particularly suited to paving long sections with a large, unchanging pave width.

Hydraulic Bolt-on Extension for a variable pave width of Fixed Screeds.

Please Note

The Hydraulic Bolt-on Extensions can only be fitted to mechanical extensions of 1m or longer. The basic screed needs to be enlarged in width by at least 1.5m, left and right sides.

Basic Screed 3m 1.5m 1.5m 0.25m 1.5m 1.5m 0.25m 0.5m 0.5m 1.5m 1.5m 0.25m 1m 1m 1.5m 1.5m 1m 1.5m 0.5m 1.5m 1.5m 1m 1.5m 0.5m 0.25m 0.5m 1.5m 1.5m 1.5m 1m 0.25m 0.5m 1.5m 1.5m 1.5m 1.5m 1m 0.25m 1m 1.5m 0.5m 1.5m 1.5m 1.5m 1.5m 1.5m 0.25m 1.5m 1.5m 1.5m 1.5m 1.5m 1.5m 1.5m 1.5m 1.5m 0.25m 0.5m 1.5m 1.5m 1.5m 1.5m 1.5m 1.5m 1m 1m 0.25m 1.5m 1.5m 1.5m 1.5m 1.5m 1.5m 1.5m 1m 0.5m 1.5m 1.5m 1.5m 1.5m 1.5m 1.5m 0.25m 0.5m 0.5m 6m 6.5m 7m 7.5m 8m 8.5m 9m 9m 9.5m 10m 10m 11.5m 11.5m 12m 12m 12.5m 13m 13.5m 14m 14.5m 15m 15m 15.5m 16m

(28)

Rear View Vertical Bracing Basic Screed 3m 1.5m 0.25m 0.25m 0.5m 6m 6.5m 1.5m 1.5m 7m 7.5m 1.5m 0.5m 0.25m 1.5m 8m 8.5m 1.5m 1.5m 9m 9m 1.5m 0.5m 0.5m 0.5m 1.5m 9.5m 10m 1.5m 0.25m 1.5m 10.5m 11m 1.5m 0.75m 0.75m 0.75m 1.5m 0.75m 1.5m 0.5m 0.25m 0.75m 1.5m 1.5m Basic Screed 3m 1.5m 0.5m 0.25m 11.5m 12m 1.5m 1.5m 12m 12.5m 1.5m 0.25m 0.25m 1.5m 13m 13.5m 1.5m 1.5m 14m 14.5m 1.5m 1.5m 15m 15m 1.5m 1.5m 15.5m 16m 1.5m 0.75m 1.5m 1.5m 1.5m 1.5m 1.5m 0.75m 1.5m 0.75m 0.5m 1.5m 1.5m 1.5m 1.5m 0.5m 1.5m 1.5m 1.5m 1.5m 1.5m 1.5m 1.5m 0.25m 0.75m 0.75m 1.5m 1.5m 1.5m 0.5m 1.5m 1.5m 1.5m 1.5m 0.5m 0.25m 1.5m

(29)

!

4.3.4 Building Up a Fixed-Width Screed with Bolt-on Extensions

Bolt-on extensions are fitted to enlarge the screed’s width. The trailing edges of the screed plates shall be flush across the entire pave width. The leading edges of the screed plates should be set higher towards the outside by roughly 0.5mm.

Horizontal braces are to be fitted in such a way that the trailing edges of the screed plates are flush.

To compensate the uplift at the outer edges of the screed, there should be a light sag of the screed when raised. The magnitude of this sag depends on the pave width. The sag can be adjusted by way of the braces over the screed’s basic unit.

In order to prevent the bolt-on extensions from bending towards the rear as a result of the pressure exerted by the mix, horizontal braces must be fitted.

Recommendation

Pave Width Sag 16m 5.5cm (approx.) 12m 3.5cm (approx.) up to 10.5m 2cm (approx.) Rear View Top View +0mm +0.5mm+0.5mm +0mm Basic Screed 1.5m 1.5m 1.5m 1.5m 1.5m 1.5m Sag

Attention!

The values indicted in the table are approximate values for set-up of the screed. When paving, the transverse evenness of the pavement needs to be checked and the braces be re-adjusted, if necessary.

(30)

4.4 Screeds at a Glance

Paver Type SUPER 600 SUPER 800 SUPER 1100-2 SUPER 1103-2 SUPER 1300-2 SUPER 1303-2 SUPER 1600-2 SUPER 1603-2 SUPER 1800-2 SUPER 1803-2 SUPER 1900-2 SUPER 2100-2 Maximum Pave Widths Screed Type AB 200 V AB 200 TV AB 340 V AB 340 TV AB 500-2 AB 600-2 SB 250 SB 300 2.7m 3.2m 4.2m 4.2m 5m 4.5m 8m 8m 7m 8.5m 9m 10m 8m 8m 8.5m 9.5m 11m 8.5m 9.5m 13m Paver Type Screed Versions for Compaction Screed Type / Systems for Compaction AB 200 AB 340 AB 500-2 AB 600-2 SB 250 SB 300 SUPER 600 SUPER 800 SUPER 1100-2 SUPER 1103-2 SUPER 1300-2 SUPER 1303-2 SUPER 1600-2 SUPER 1603-2 SUPER 1800-2 SUPER 1803-2 SUPER 1900-2 SUPER 2100-2 V TV V TV TV TP1 TP2 TV TP1 TP2 TV TP1 TP2 TVP2 TV TP1 TP2 TVP2 X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X

(31)

!

4.5 Set-Up of Tamper

The tamper shall be set to an identical stroke length across the entire pave width. The setting can be changed by simply turning the eccentric bush on the shaft driving the tamper bar. The driving shaft is accessible from behind, so that this can easily be done between job site sections. Adjusting the lower reversal point of the tamper bar, however, takes more time. First, the tamper shields need demounting. Then remove the screws on all shaft brackets. After loosening the locking nut (2), the tamper bar can be adjusted via bolt (1). The height to be set depends on the tamper stroke selected.

Tamper Stroke 2mm

The tamper bar at the lower reversal point is flush with the bevelled edge of the screed plate.

Eccentric Shaft at Lower Reversal Point

4.6 Set-Up of Tamper Shield

The tamper (3) must be set so that it rests on the wear strip (1) across the full width. Then adjust the spring steel bar (2) on the tamper shield by means of screw (4) from the rear of the screed until a gap of 0.5 - 1mm is obtained between tamper bar and the spring steel bar. Release screws (6) and fit various small shims (5) to align the tamper shield. With the tamper shield correctly aligned, the spring steel bar (2) is at least parallel with the tamper or preferably inclined slightly to the front.

Check the clearance between tamper and spring steel bar and correct, if necessary.

0mm

Tip!

At a stroke length of 2mm, the tamper bar should be flush with the screed plate (check with your hand).

The tamper bar at the lower reversal point is 1mm lower (maximum) than the bevelled edge of the screed plate.

The tamper bar at the lower reversal point is 3.5mm lower than the bevelled edge of the screed plate. Screed Plate Tamper Stroke 2mm Bevelled Edge of Screed Plate 0mm Screed Plate Tamper Stroke 4mm Bevelled Edge of Screed Plate 1mm Screed Plate Tamper Stroke 7mm Bevelled Edge of Screed Plate 2.5mm Screed Plate Bevelled Edge of Screed Plate 1mm at Stroke Length of 4mm Tamper 0.5 − 1mm

1

2

6

5

4

3

1

2

(32)

4.7 Set-Up of Pressure Bar(s)

4.8 Bevel Irons

1. Unscrew the nut (2) with anti-twist device (3) on the hydraulic ram (1) for the pressure bar.

2. Turn the hydraulic ram (1) to adjust the height of the pressure bar. The clearance (7) between pressure bar and bottom edge of the screed plate should be at least 4mm. 3. Check that the hydraulic ram for the pressure bar makes contact with metal plate (5)

when retracted.

4. Set pre-tension of spring (6) to 5.5mm via nut (4) to yield a distance (8) of 59.5mm. 5. Resecure the hydraulic ram (3) for the pressure bar.

0.5 − 1mm

Bevel irons shape and compact the edges of the pavement.

They are available with a bevel edge of 45° and 60°. Their size depends on the thickness of the layer to be paved.

A heating rod can be installed as an option to improve the sliding properties of the bevel iron.

Screed Plate Pressure Bar 4mm 59.5mm 0.5 − 1mm Layer Thickness Angle 45° 60° 4 − 6cm 6 − 12cm 12 − 18cm

1

2

4

6

4

3

5

8

7

(33)

!

+

4.9 Function Check of Screed Heating

All screed components in contact with the hot mix should be heated to approx. 90 °C before starting work.

It is recommended to protect the screed against excessive loss of heat to the surroundings so that the heating power can be utilized effectively, for instance by putting down the screed, preferably on hot mix.

Asphalt may stick to the tamper bar, screed plates or pressure bar(s) if the screed temperature is too low. This can lead to the formation of strips and an irregular surface texture.

The floating behaviour of the screed may vary before it reaches its operating temperature, with the result that layer thickness may also vary and deviate from the desired one.

Tip!

Directly after switching on screed heating, correct operation of the heating rods can be checked by cautiously touching the tamper bar, screed plates and pressure bar(s).

For the “dash 2“ machines, a monitoring unit for screed heating is available as an optional extra. This feature monitors each single heating rod for proper function and indicates any fault without delay.

Should one of the green indicator lights extinguish over a prolonged period of time, then the reason may be:

n Poor insulation

n Asymmetrical power consumption

n Generator temperature too high

Advantage

A failure of heating rods is detected immediately. New parts can be procured without delay to promptly restore the screed‘s full functionality.

1 Engine 2 Control Desk 3 Control Box / Fuse Box 4 Distributor Box 5 Generator 6 Tamper with Heating Rod 7 Screed Plate with 2 Heating Rods

1

2

5

6

7

4

3

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5.1 Paving Material . . . 66 5.2 Paving Parameters . . . 67 5.3 Paver Set-Up . . . 67 - 69 5.4 Relationship Between Tamper Speed and Pave Speed . . . 70 5.5 Recommended Settings for the Compacting Systems . . . 71 5.6 Functions of the Hydraulic Rams for Raising / Lowering the Screed . . . 72 - 73

(35)

Mix Temperature - The mix temperature should be constant and high enough to prevent the mix from cooling before it is laid. - Paving material that has cooled is harder to compact. - The load bearing capacity of the mix, too, depends

on its temperature.

- Feed of the paver with mix shall be planned with a view to an optimal temperature for paving.

Grain Size - The maximum grain size should not exceed 1/3 of the

layer thickness.

Mix Composition - The composition of the mix should remain constant

throughout the paving job.

Properties of the Mix - Properties of the mix have an influence upon the screed’s

floating behaviour.

- Paving materials with a high bearing capacity confront the screed with a higher resistance than materials of poor bearing capacity.

- Conveying and compacting systems can be set up in an optimal manner to match the type of mix.

Layer Thickness - The larger the layer thickness, the larger the screed

planing angle.

Pave Width - The floating behaviour of the screed changes

in accordance with the pave width.

Paver Stop - The longer the paver stop, the greater the irregularity

to be expected in a longitudinal direction.

Ambient Conditions - Ambient conditions, such as temperature,

can influence the mix and change the floating behaviour of the screed.

5.1 Paving Material

5.2 Paving Parameters

5.3 Paver Set-Up

- If there is a too large head of mix in front of the screed, the mix may cool, thus having an adverse effect upon both pre-compaction and the screed‘s floating behaviour. - A constant head of mix in front of the screed is

a precondition for perfect floating of the screed. - The thicker the layer, the greater is the upward force

exerted on the screed.

- Proportional control of conveyors and augers provides for an optimal head of mix in front of the screed.

Head of Mix

(36)

- The length of the tamper stroke and the tamper speed are factors influencing pre-compaction of the mix and floating of the screed.

- On VÖGELE screeds, the tamper stroke can be set to 2mm, 4mm or 7mm. The longer the tamper stroke, the higher the pre-compaction and the compaction depth. For this reason, the length of the tamper stroke should be set in accordance with the layer thickness in order to obtain the smallest possible, positive screed planing angle. A negative screed planing angle may result if the tamper stroke is too long for the layer thickness paved. This can lead to an open-textured, cracked surface structure and uncontrolled levelling resulting in irregularities.

Tamper Stroke Tamper Speed

- Both the tamper speed and the pave speed have a major influence on pre-compaction of the mix. This means that the tamper speed must be adjusted in accordance with the pave speed or vice versa. An optimal relationship has not yet been found. For this reason, the values must be individually adjusted until the smallest possible, positive screed planing angle is obtained and wear on the compacting systems is minimized.

Tamper Speed

- When making major changes or one-sided changes to the screed planing angle, torsion of the screed may result.

Rigidity of the Screed

- Screed Freeze is a briefly activated feature following a paver stop in Screed Float mode. A pressure of about 30 bar is applied to the piston side of the hydraulic rams for raising / lowering the screed in order to prevent it floating up when resuming paving.

Screed Freeze

- The pave speed determines the impact of the compacting systems on the pavement.

- Pave speed and head of mix in front of the screed must be well adapted to each other.

- When paving at a high speed, large quantities of paving material are consumed, which requires good job site logistics for supply of the paver with mix. - The pave speed shall be selected so as to obtain

as constant a supply of mix from the feed trucks as possible.

- As the pave speed has a major influence on pre-compaction, it should be set so that the positive screed planing angle is not too large, as this would promote irregularities. The pave speed should, therefore, be set to a value ensuring good pre-compaction with the screed floating on the mix at a small planing angle.

Pave Speed

- When paving thick layers, the vibration frequency has little influence upon compaction. Vibration is far more important when paving wearing course, as it promotes the formation of a close-textured, even surface behind the screed.

Vibration Frequency

- The pressure bar(s) are moved up and down by a pulsed hydraulic pressure. These pulses are generated by a rotary valve in the screed at a rate of between 58 and 68 Hz. Hydraulic rams press the pressure bar(s) downwards over the entire pave width. At the end of each pulse, the pressure bar(s) are returned to their original positions by springs acting against the force of the rams. The pressure applied to the pressure bar(s) changes the distance travelled by the pressure bar(s)

Frequency / Pressure of Pressure Bar(s)

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5.4 Relationship Between Tamper Speed and Pave Speed

While paving, when screed tow point rams are not changed in position, an equilibrium

of forces comprising pave speed, screed weight and tamper speed is established.

If any one of these parameters changes, this immediately affects the screed‘s floating

behaviour.

Tamper speed and pave speed are very strongly dependent on one another. Any change in pave speed without changing the tamper speed and position of the screed tow point rams will affect pre-compaction of the mix. If the pave speed is increased without simultaneously increasing the tamper speed, the load bearing capacity of the mix will be reduced and the screed lay a thinner layer at a steeper planing angle.

Paving with Automated Grade and Slope Control

If Automated Grade and Slope Control is used for paving, the desired elevation of the screed can be maintained by increasing the planing angle, but pre-compaction will not remain constant.

After Compaction by Rolling

When the roller passes over the mix, the amount of extra compaction will differ on account of varying pre-compaction and result in irregularities in the surface.

5.5 Recommended Settings for the Compacting Systems

Kind of Layer

Wearing Course Binder Course Base Course

m/min. > 5 4 − 10 2 − 8 Stroke _{2 − 4} ₄ _{4 − 7} (mm) Revs/min. 300 − 800 800 − 1,200 1,200 − 1,800 Pressure _{50 − 80} _{70 − 90} _{80 − 100} (bar) Revs/min. 1,200 − 2,000 1,500 − 2,500 2,000 − 3,000 Pressure _{45 − 70} _{60 − 90} _{90 − 110} (bar) Frequency _{58 − 68} _{58 − 68} _{58 − 68} (Hz) °C > 120 > 120 > 120 Pave Speed Tamper Speed Vibrators Pressure Bar(s) Compacting Temperature 8m/min. 4m/min. Pave Speed Low Pre-compaction High Pre-compaction 8m/min. 4m/min. Pave Speed 8m/min. 4m/min.

(38)

!

5.6 Functions of the Hydraulic Rams for Raising / Lowering the Screed

Screed Float

Normally, mix is paved with the screed in Screed Float mode. In other words, the piston-side and rod-side valves operating the hydraulic rams are open for free up and down movement.

Screed Assist

If the bearing capacity of the mix is poor, the screed will not reach the desired elevation even when set to a large planing angle. The Screed Assist function allows pressure to be applied separately to the right and left-hand hydraulic rams from below. This pressure counteracts the screed weight and allows it to float up in accordance with the magnitude of the pressure.

Screed Freeze

The Screed Freeze function is activated automatically following a paver stop in Screed Float mode. The valves activating the hydraulic rams for raising / lowering the screed are closed on both the piston and the rod sides, thus briefly suspending the Screed Float mode in order to prevent irregularities in the pavement when resuming paving.

Attention!

Do not use for wearing course!

Screed Float

Screed Assist Pressure

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6.1 Basic Principles . . . 76 - 77 6.1.1 Setting the Layer Thickness . . . 78 - 79 6.1.2 Weather Conditions when Paving Asphalt. . . 80 6.1.3 Requirements Made on the Base and Sub-Base . . . 81 - 83 6.2 Augers and Limiting Plates for the Auger Tunnel on an Extending Screed . . . 84 - 85 6.3 Head of Mix in Front of the Screed . . . 86 6.4 Definition of the Route . . . 87 6.5 Correct Use of NIVELTRONIC®_{. . . 88} 6.5.1 Automated Grade and Slope Control . . . 88 6.5.2 Development from NIVELTRONIC®_{to NIVELTRONIC Plus}®_{. . . 89} 6.5.3 Quick Reference Guide for NIVELTRONIC® and NIVELTRONIC®_/ V-TRONIC®_{. . . 90 - 92} 6.5.4 Quick Reference Guide for NIVELTRONIC Plus®_{. . . 93 - 95} 6.5.5 Components of NIVELTRONIC®_{. . . 96 - 99} 6.5.6 Use of Different Grade Sensors . . . 100 - 103 6.6 Position of Sensors for Control of the Floating Screed (Example: Referencing from Stringline) . . . 104 6.7 Position of the Grade Sensor in Transverse Direction . . . 105 6.8 Use of Screed Assist. . . 106 - 107 6.9 Joints between Lanes . . . 108 6.9.1 Paving “Hot to Cold” . . . 108 6.9.1 Paving “Hot to Hot” . . . 109 6.10 Joints in Asphalt Pavements . . . 110 - 112 6.11 Expansion Joints . . . 113

(40)

6.1 Basic Principles

n

Before starting work, the minimum

and maximum pave widths

should be established and the

paver be set up accordingly.

n

The paving sequence should

be co-ordinated with the other

teams on site in order to assure

the supply of material and

prevent the hot mix being

driven over too soon.

n

The feed vehicles must be

organized in such a way as

to ensure a continuous supply

of mix with as few paver stops

as possible.

n

Check with the mixing plant(s)

to ensure that mix will be supplied

as planned.

n

Check serviceability of the road

paver (filling levels, electrical

and hydraulic functions, etc.).

n

The feed vehicle’s tarpaulin cover

should only be removed just

before dumping the hot mix

in order to prevent it cooling.

n

The pave speed should be as

constant as possible. If mix

can only be supplied to a limited

extent, it is better to continue

paving slowly and uniformly

than to interrupt the process

by paver stops.

n

In the event of prolonged

disruptions in the supply of mix

and in cool weather, it is advisable

to use up the entire mix stored

in the paver and then to lift up

and clean the screed. The screed

can be re-lowered and the work

continued when the supply of mix

is resumed.

n

The composition and temperature

of the mix should be checked

regularly.

n

The layer thickness should be

checked regularly while paving

in order to avoid errors.

n

When using Automated Grade

and Slope Control, the sensors

must be checked to ensure that

they are operating correctly.

n

Paving by hand should only be

done in exceptional cases, such

as on small surfaces or in corners

inaccessible to the paver.

n

The rollers used for subsequent

compaction must be dimensioned

in accordance with the mix

(compactability), paved area

in square metres, temperature

of the mix, surroundings and

base so that roller compaction

is completed before the mix

has cooled.

n

The pavement should only be

re-opened to traffic when the

temperature of the mix has

dropped below 40 °C in order

to prevent any risk of deformation.

n

The pave speed should be kept

constant throughout the paving

job, if possible.

n

At the end of the day or between

paving sessions, a transverse

joint is to be installed.

n

Adjustments on the screed

while paving should be kept

to a minimum.

n

The paver’s material hopper

should not be run empty

(to avoid segregation).

n

If no kerbstones are installed,

wearing course should always

be paved with the screed in

Screed Float mode. Do not use

Automated Grade and Slope

Control.

(41)

6.1.1 Setting the Layer Thickness

Due to the numerous parameters influencing the paving process, it has hitherto been

impossible to develop a formula supplying exactly the right value for setting the tow

point rams for a required layer thickness. When working with Extending Screeds,

the general rule is: layer thickness in cm + (50 to 100%) yields roughly the values

to be set on the paver’s scales for layer thickness. The settings must be checked after

paving the first few metres and corrected as required.

H = Layer Thickness S = Specified Thickness

W = Amount of Compaction by Rolling The screed only pre-compacts the mix. Final density is achieved through subsequent compaction by rolling. Rollers compact the mix by an amount (W) somewhere between layer thickness (H) and the specified thickness (S). (W) is the amount of subsequent compaction by rolling and must be taken into account when setting up the screed.

The planing angle α results when setting the layer thickness H + (50 to 100%) via the tow point rams using the layer thickness scales. The layer thickness should be checked immediately when starting paving so that the position of the tow point rams can be corrected if necessary.

Since, on account on its floating behaviour, the screed would have to travel a certain distance before reaching the layer thickness, it is recommended to put the screed down on timbers or uniformly spread material level with the layer thickness.

After rolling, the surface must be checked to ensure it has the specified thickness. If not, the layer thickness must be corrected again until the correct result is obtained after rolling. Scale for Layer Thickness α H W S H H S

(42)

6.1.2 Weather Conditions when Paving Asphalt

On the majority of job sites, weather conditions can only be taken into account

to a very limited extent because of the tight scheduling. However, this can give

rise to problems when paving hot mix. In very cold conditions and if the distance

between mixing plant and road paver is relatively long, the temperature of the

mix may well have dropped to the lower limit permissible for paving.

6.1.3 Requirements Made on the Base and Sub-Base

n Depending on the bitumen type used, it will be difficult for the rollers to achieve the specified final density if the temperature of the mix is below 120 °C when dumped from the feed lorry into the paver’s material hopper.

n Since the ambient temperature causes the asphalt to cool more rapidly, wearing course should not be paved at temperatures below 3 °C or better still below 6 °C.

n Binder course contains more coarse grains which retain heat, with the result that such layers can still be paved at temperatures around zero.

n It may even be possible to pave base course at temperatures as low as -3 °C, but be sure that the sub-base is always free from ice and snow.

n The decision whether or not paving is possible should not be made dependent on air temperature only: the temperature of the base must also be taken into account, as a cool base will similarly cause the mix to cool more rapidly.

n Paving on a wet or puddled base is not recommended. Water vapour may form under the paved layer when the hot mix comes into contact with moisture. Since this vapour strives to escape upwards, it produces cavities which will impair the bearing capacity and pre-compaction of the mix and may also have a negative effect on the screed‘s floating behaviour.

n Formation of vapour is normally unlikely when paving fresh emulsion, as the boiling point is very much higher.

n The sub-base under a non-bonded base must be level, stable and perfectly compacted, so that the asphalt pavement uniformly retains its load bearing capacity for a long time after being paved.

n It is advisable to hand over the sub-base with official acceptance guaranteeing that the load bearing capacity, evenness, as well as longitudinal grade and transverse slope meet with the requirements specified in the planning.

n When paving an asphalt layer on a bonded base, it should also be level, stable and compacted, just like the non-bonded base. Preliminary level regulating measures may be necessary if the sub-base is very uneven.

n It is also important to check the height of any shafts, drains or hydrants so that they cannot obstruct the paving process and remain accessible afterwards.

n The base must be cleaned by sweeping or with compressed air or a jet of water in order to ensure good bonding between pavement and base.

n The surface must then be sprayed with bitumen emulsion or a tack coat so that the freshly laid mix bonds with the base.