Paver Makers Refine Controls, Width Changes and Reliability


Construction Lifting & Concrete Placement


 Terex Roadbuilding concrete paver
Terex Roadbuilding relies on hydraulic sensing and grade control, and is pursuing better profilograph reports by taking the flex out of its new SF-3502B paver frame with 26-inch support tubes.
 GOMACO paver
 GOMACO V2 mold
GOMACO added variable-width paving to its paver line with the hydraulically adjustable V2 mold. The mold's two parts (bottom image) can be shifted automatically by GOMACO's G21 electronic controller.


The confines of the concrete-paver market -- where only seven manufacturers produce the 30 models of slipform pavers available in North America today -- contain a startling variety of technology adoption and application. Buyers continue to demand refined control over pavement smoothness to satisfy project owners and flexibility to change paving widths and transport equipment quickly and easily, all in a package that is durable and reliable. Each of the seven manufacturers serving concrete pavers in North America answers those demands with a unique approach.

GOMACO has teamed up with Leica to adapt laser grading technology to control paving pans without string lines. It has proven effective when plugged into the manufacturer's G21 electronic system, and the next phase in adoption shifts from technical to political, as the industry works to convince more specifying agencies that stringless paving can produce quality pavements at lower cost.

GOMACO recently introduced a new option to address the need for the ability to change pavement widths without interrupting the paving process. The company's V2 is a dual-mold system that is hydraulically adjustable for paving at different widths. The positions of the front and rear molds relative to each other dictates the width of the pavement, and there is a separate control for each half of the mold.

An optional auto-width adjustment package uses sensors to manage on-the-go changes in paving width to produce a tapered slab. String line is set for the desired taper, and sensors on the paver follow it to control the hydraulic cylinders that extend the frame and side-shift the mold. The operator switches the system on when approaching a width transition, and the mold adjusts automatically to the new paving width. This stand-alone package can be installed on any GOMACO paver with the V2 mold.

Terex Roadbuilding is pursuing better profilograph reports by building its new SF-3502B paver frame with 26-inch support tubes. The idea is to minimize frame deflection even when paving at the machine's 33-foot maximum width.

Terex designed the two-track SF-3502B with telescoping walkway, handrails, and vibrator manifold to reduce the time needed for width changes and transport.

Guntert & Zimmerman's machine-control microprocessor offers many options for delivering smooth pavements, and was instrumental in helping Concrete Placing Co. win one of the American Concrete Paving Association's 2005 Excellence in Concrete Pavement Awards.

The contractor was paving a three-mile stretch of US-93 in the Ashley Creek project in Kalispell, Mont. Repeated rain days required some innovation to complete the work on time. Most of the work was paved without string lines using a Guntert & Zimmerman S-850 Quadra paver. After following strings to pave the first lane, each succeeding lane was paved using the preceding lane as a reference. Programming the desired cross-slope of the lane into the paver's computer automatically controlled the elevation on the outside lane edge.

The grade system in Power Pavers' two twin-track concrete pavers uses four hydraulic grade cylinders -- two mounted on each track -- controlled by four proportional hydraulic sensors. They can reference dual string lines or they can be locked to grade. Steering can also be controlled by a proportional hydraulic sensor, which can be deployed on either the right or left side of the machine.

HEM also uses all-hydraulic paving-pan controls. The company has been upgrading its entire paver line, though, with features such as a hydraulically sliding frame. The system, first applied to its Model 8¨C16 last year, now is available on Models 12¨C27 and 14¨C37, and it allows these pavers to change paving width while they are slipforming.

HEM has also added an automatic dowel-bar inserter, and canal-paving options for its slipform pavers. For fast loading and transport, the pavers use an outrigger lift system similar to that used on Power Pavers machines to raise the machines high enough for a lowboy trailer to be backed under them.

Rexcon redesigned most of the Town & Country's control system in the past year, replacing many electrical controls with hydraulic sensors, and the screw jacks with hydraulic cylinders.

Auger-control cables and tamper-bar cables were replaced with electrical controls, but these new electrical controls forego the control boards that Rexcon once used, greatly simplifying troubleshooting and repairing the systems.

Clearly, some manufacturers are still improving their concrete pavers to match the industry's reliability standards. Many makers continue to build their product lines on machines that rely on tried-and-true hydraulic sensing and paving control to deliver quality paving, and some are stretching the technology envelope at the leading edge of what can be done with electronics to meet smoothness standards most quickly and easily. An increasing number of models are engineered with the ability to change paving widths without interrupting the flow of mix through the paver, and virtually all of the mid-sized pavers on the market are designed to be ready to transport with minimal investment of time and support equipment.

Despite the small number of manufacturers and machine models available, it seems there's a combination of technology, versatility, and price for almost any buyer.

Concrete-Paver Specifications (by maximum paving width)
Model Max. Paving Width* Gross Horsepower Transport Width Operating weight (lb.)
* With extensions
Source: Xpanded Specs
Projected Allen ASF 1600 2T HP 16' 0" 200 11' 11" 44,000
HEM 8¨C16 16' 0" 179 8' 6" 33,100
GOMACO Commander III-4T 20' 0" 200 8' 3" 33,400
GOMACO GT-6300-4T Slipform 20' 0" 155 8' 2" 28,500
Terex RB SF-2204 HVW 20' 0" 250 8' 6" 55,000
Allen ASF 2700 2T LP 27' 0" 265 16' 4" 48,000
HEM 12¨C27 27' 0" 240 8' 6" 59,000
Allen ASF 3200 2T HP 32' 0" 325 14' 0" 52,000
GOMACO GHP-2800-4T 32' 0" 335 8' 2.5" 80,000
GOMACO GP-2600-4T 32' 0" 275 9' 9.8" 79,000
GOMACO GHP-2800-2T 32' 0" 335 12' 0" 70,000
GOMACO GP-2600-2T 32' 0" 275 11' 10.7" 75,000
Power Pavers SF-2700 32' 0" 215 12' 0" 48,000
Power Pavers SF-3000 32' 0" 250 14' 0" 65,000
Terex RB SF-3502B 33' 0" 350 12' 0" 73,000
Guntert & Zimmerman S850 Quadra 34' 0" 335 12' 0" 90,200
Guntert & Zimmerman S850(ST) 10¡ä 34' 0" 335 12' 0" 80,000
Guntert & Zimmerman S850(ST) 12¡ä 34' 0" 335 12' 0" 90,200
RexCon T&C I 34' 0" 325 11' 0" 60,000
HEM 14¨C37 37' 0" 325 8' 6" 82,850
Guntert & Zimmerman S1000 44' 0" 335 n/a 95,500
Terex RB SF-6004 44' 0" 400 10' 2" 115,000
GOMACO GP-4000-4T 50' 0" 450 9' 8" 115,000
GOMACO GP-4000-2T 50' 0" 450 9' 8" 88,000
Guntert & Zimmerman S1500 56' 0" 425 n/a 106,500



Web Resources
GOMACO Guntert & Zimmerman
HEM Power Pavers
RexCon Terex Roadbuilding