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Seven new screeds have
been introduced since 2001,
and demands for density and smoothness are fostering new interest in
Euro-style models.
Although paver sales have been slow for the past several years,
manufacturers have been busily adapting their screed lines to changing
markets and market conditions.
For Caterpillar,
this has meant extending their line of hydraulically extendible screeds to
offer front-mounted extender designs as an alternative to their traditional
rear-mounted extenders. Cat representatives explain simply that a certain
portion of the market will only buy the front-mounted design, and Cat wants
to be a player in that market segment, too.
For IR-Blaw-Knox,
the trend among paving contractors toward versatile machines that can handle
anything from a parking lot to a major highway job brought the introduction
of a new rubber-track paver and a new 8-foot extendible screed capable of
high-performance paving at widths of 15 feet or more.
For Cedarapids, the demand for high performance paving lead to the
development of a new generation of highway-class screeds with a special
focus on the heating system.
Roadtec, too,
has responded to a demand for high-performance screeds that can hit
performance specifications that are now critical to a paving contractor’s
profitability. Rolled out at the World of Asphalt show in March, Roadtec’s
Eagle 10 is the very latest screed introduction.
And North America’s growing use of performance-grade pavements,
especially stone matrix asphalt, has stirred new interest in European-style
screeds. One of IR-ABG’s high density, double-tamping bar designs was
featured in a major Better Roads feature on SMA paving early this year (When
Precision and Density Mean Everything, January ‘03). Bitelli,
recently acquired by Caterpillar, introduced its latest screed to North
America in March. And the former Pro-Pave line of pavers has access to the
technology of Vogele, Europe’s largest-selling paver company, since its
purchase by Wirtgen;
the line now operates under the Vogele brand name in North America, though
the product line is primarily designed and built here.
Here is a quick look at who’s who in the screed market and what they’ve
been doing lately.
Recent Screed Introductions
2001
2002
2003
Roadtec
Newest extendible screed gets latest improvements
 Roadtec rolled
out its newest production screed this spring, the Eagle 10. The new screed
extends hydraulically from 10 feet to 19 feet, 6 inches and features
electrically heated screed plates as standard equipment. Roadtec says its
aluminum heating elements provide even heat from front to back and end to
end. The crown mechanism features an easy-to-tension chain between
turnbuckle sprockets and between drive and turnbuckle sprocket.
Roadtec says the trailing extender design enhances material flow and
eliminates the need for pre-strikeoffs in front of the main screed.
The unit features dual 5-inch, plated guide tubes and spring-loaded
two-piece end gates. The generator is mounted under the tractor’s access
ladder to improve auger visibility, and the solenoids are accessible from
the side. Other access features include a wider extendable walkway, and
better access to the tipping frame pivot for rear screed alignment.
Click 15 on ROADFAX card
Caterpillar
Hydraulic screed with front-mounted extenders
 Cat began
expanding its line of hydraulically extendible screeds in 2001 with the
introduction of the AS2301, featuring front-mounted extenders. The new model
was created as an alternative to Cat’s rear-mounted extendible screed, the
Extend-A-Mat 10-20B. The AS2301 extends hydraulically from 10 feet to
18-feet wide, and can go to 24 feet with optional bolt-on extensions.
Optional cutoff shoes can reduce the minimum paving width to 8 feet.
Standard features includes a pair of patented pre-strikeoff shields
positioned at the front of the screed to make initial contact with the mix
after it passes through the augers. They allow the proper amount of material
to enter the area in front of the main screed. When thickness screws are
used to adjust mat depth, the height of the pre-strikeoff shields
automatically changes to follow the leading edge of the main screed.
Cat also markets a full line of fixed-width screeds.
Click 12 on ROADFAX card
Ace Group
Longer-lasting screed components
 Ace
Group claims its Acebond chromium carbide screeds and components will last
four times longer than competing products. The company’s screeds and
floors and chain and bar assemblies for various paving and pickup machines
come in complete assemblies, ready for installation.
Click 17 on ROADFAX card
Caterpillar
 Caterpillar
added to its line of hydraulically extendible screeds with front-mounted
extenders last year by introducing the AS2251. The new model was created as
an alternative to Cat’s 8-foot, rear-mounted extendible screed, the
Extend-A-Mat 8-16B. The AS2251 extends hydraulically from a base width of 8
feet, 2 inches to 14 feet, 5-inches wide; optional bolt-on extensions can
increase the paving width to 20 feet, 5 inches. Optional cutoff shoes can
reduce the minimum width to 6 feet, 2 inches.
Like the larger AS2301, the AS2251 features pre-strikeoff shields to
control the amount of material entering the area in front of the screed. The
front-mounted extenders are supported by two 2-inch-diameter shafts that
provide torsional resistance and rigidity.
Cat recommends the AS2251 for a variety of production paving
applications, including highways and large parking lots.
Click 13 on ROADFAX card
IR Blaw-Knox
More mat texture and density
 Blaw-Knox
launched its new hydraulically extendible Liberty screed this spring as a
high-performance option on the new PF875L track-mounted paver/finisher. The
Liberty screed has a base width of 8 feet and can be extended hydraulically
to 15 feet; it’s maximum paving depth is 6 inches.
The screed was designed to bring new standards for rigidity and strength
to its class. Blaw-Knox says it has the industry’s largest-diameter,
extension-guide tubes which, combined with a rigid extension slide design,
minimizes screed deflection at wide paving widths. Its structural strength
and rigidity also contribute to what the company says is a key feature: full
adjustability of the extensions to the main screed. The operator can easily
adjust the height of the extension as well as the angle of attack, which is
said to enhance mat quality across a broad range of paving depths, widths,
and mix designs.
Two other features contribute to the production of a superior mat,
according to the company. It features consistent, comparable screed depths,
with the main screed at 15-inches deep and the extensions at 8-inches deep.
And it is designed to produce mat density, with an operating weight of 2,600
pounds and a maximum vibration frequency of 2,800 vpm.
Click 14 on ROADFAX card
Vogele America
Heavy box frame design produces mat quality
 Vogele says
its HS 1020B hydraulically extendible screed uses a unique box frame design
and massive weight to produce superior mat density and smoothness. The
9,130-pound screed extends from 10 feet to 19 feet, 6 inches hydraulically,
and up to 25 feet, 6 inches with fixed extensions. It can generate vibration
frequencies up to 2,800 vpm and has a maximum paving depth of 12 inches.
The box frame is designed to provide maximum strength and rigidity to
eliminate flexing and prevent screed extenders from loosening over time. The
screed has a one-piece, solid backbone with no joints.
Vogele says its exclusive sloping extender design provides maximum
rigidity and allows each end of the screed base to slope independently of
the screed frame. The unit’s pre-strikeoff provides a continuously rolling
uniform head of material in front of the screed for uniform mat consistency
at all paving widths. This feature is also said to prevent excessive
material build up between the main screed and the extension screed, allowing
easy extension movement at all widths.
Heavy duty guide tubes inside the support are permanently aligned to
withstand full material head and shear force resistance, even at the widest
paving width.
Click 16 on ROADFAX card
Bitelli
Enhances paver performance
 Bitelli
introduced the RB 4650 VB screed early this year for its BB 650, BB 651, and
BB670 asphalt pavers. The new unit extends hydraulically from 8 feet, 2
inches to 15 feet, 3 inches; with fixed extensions it can pave up to 19
feet, 8 inches. Key features include longer screed plates for increased
stability and service life, improved burner profile for more even heat
distribution, and electronic ignition and automatic temperature control for
a simpler operation and consistent control of mix temperatures.
Bitelli is a Caterpillar subsidiary.
Click 18 on ROADFAX card
IR-ABG
High-density paving
 IR-ABG
markets four versions of its high-density Duotamp vibratory screeds. The
fixed-width VDT 120 paves 9-feet, 10-inches wide, and the VDT 121 paves
8-feet, 2-inches wide. The VDT-V 78 is hydraulically extendible from 8 feet,
2 inches to 16 feet, 5 inches, and the VDT-V 88 extends from 9 feet, 10
inches to 19 feet, 8 inches.
All four models feature ABG’s dual vibrating tamper bars which,
combined with their massive weight, allow the paver to achieve high degrees
of compaction at the screed and, ultimately, exceptional smoothness. A VDT
120 used with an ABG Titan 525 paver produced 92% compaction at the screed
last year in a stone matrix asphalt project in Virginia.
ABG’s high-density screeds are available with Titan models 325 EPM,
423, and 525. The high density screeds are also recommended by ABG for
paving roller-compacted concrete.
Click 19 on ROADFAX card
Cedarapids Paving
Electric heat screeds stretch hydraulically
 Cedarapids
rolled out its Stretch 16 and Stretch 20 hydraulically extendible, electric
heat screeds last year, touting their fast heat-up cycles and uniform heat
distribution over the entire length and width of the screed. In addition to
improving performance and increasing mat quality, Cedarapids says the
Stretch screeds eliminate the fuel oil and offer a safer, smoke-free
operation for crews.
Electric heat comes from 20- and 34-kW generators (depending on the
screed model). Each zone of the extendible screed has its own thermostat to
constantly monitor screed temperatures and automatically maintain set
temperatures. The company says this eliminates the restarts necessary for
maintaining heat settings with many fuel oil screeds and other electric
screeds.
Stainless-steel heater bars in the main and hydraulically extendible
screed sections are sealed to prevent water from entering the chamber,
reducing the possibility of damage. The heater elements are insulated from
the screed’s upper frame to improve efficiency and enhance operator
comfort.
Click 11 on ROADFAX card
Reprinted from Better Roads June 2003 issue
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