Equipment Type

Concrete Paver Innovation, New Techniques Gain Ground

Concrete-pavement industry moves cautiously ahead as it waits for a new highway bill

December 20, 2013

The road-building industry is in a state of transition, says Bill Davenport, vice president of communications for the American Concrete Pavement Association (ACPA). “We’re generally moving away from the construction of new pavements and taking on more rehabilitation, restoration, and preservation,” says Davenport, “a trend likely to continue and one that we expect to be reflected in both the current and next highway bill.”

Cutting Overlay Joints

According to the American Concrete Pavement Association (ACPA), the design of concrete overlays bonded to the asphalt surface of an existing roadway generally calls for relatively closely spaced transverse and longitudinal joints in order to mitigate mid-panel cracking. The resulting small-panel size, says the ACPA, also causes potential failure modes to change, generally, from bottom-up cracking to corner and top-down cracking.

To facilitate sawing the numerous transverse and longitudinal joints that might be required in a particular overlay design, HEM Paving’s MagnaCut Concrete Sawing System automates the process. Five adjustable saws under the machine cut longitudinally, and two saws on a transverse guide at the front each travel halfway across the pavement for transverse cuts. The addition of a second transverse-cutting system is under design.

 

The current highway bill, MAP 21 (Moving Ahead for Progress in the 21st Century), is a two-year, $105-billion appropriation that is set to expire September 30, 2014. In the months ahead, the road-building community will be focused on the progress Congress makes toward a new bill, hoping that a long-term appropriation will result, but remembering that the former bill, SAFETEA-LU, limped along for nearly three years with 12 short-term extensions after its 2009 expiration.

The industry is aware, too, that the Highway Trust Fund (HTF), which is the funding mechanism for an estimated 45 percent of the nation’s annual expenditure for road and bridge work, has experienced increasing shortfalls, the result, in part, of more-fuel-efficient vehicles, conservative driving habits, and inflation. Congress has subsidized the HTF from the general fund since 2008, and another $12.6 billion is approved for 2014.

Cost of Ownership

Size class (lb.) Average Price Hourly Rate*
19,000-27,999 $120,000 $76
28,000-39,999 $190,000 $112
40,000-54,999 $265,000 $154
55,000-96,999 $418,000 $268
97,000 & heavier $534,000 $348

*The average hourly rate is the monthly ownership cost divided by 176, plus the hourly operating cost.

Unit prices used in this calculation: Diesel fuel $3.98/gallon; Mechanic wage $54.21/hour; Money cost 1.75 percent.

Source: EquipmentWatch.com

Debate continues, then, about increasing the federal gas tax (the HTF is funded chiefly from taxes—last raised in 1993—on gasoline, gasohol, and diesel fuel) and about new funding options, such as user fees based on vehicle miles traveled.

“The road-building industry needs a highway bill with both the funding levels and duration necessary to encourage investment,” says Davenport. “Businesses are more willing to invest if the highway bill is a known quantity. The process of serial funding by continued resolution and the failure to develop a traditional six-year bill places the industry in the untenable situation of having only short-term outlooks on the future.”

Market perceptions

The uncertain status of the next highway bill and a sense of uneasiness about the economy in general seem to be having a dampening—but not debilitating—effect on sales of mainline concrete paving machines.

“Some highway contractors have stepped up to purchase new paving spreads,” says Wade Boman, national sales manager, concrete slipform products, for Wirtgen America, “but this kind of purchase would be much easier to make if we had proper, multi-year highway funding in place.”

Ron Meskis, president of Guntert & Zimmerman, says that from his point of view, the domestic market is generally soft, in some measure the result of uncertainty about the future of a long-term highway bill. Emerging economies elsewhere in the world, however, are spending huge sums on infrastructure development, says Meskis, resulting in increased overall market activity for domestic equipment makers.

Roger Bockes, HEM Paving, also sees international interest in slipform pavers as “very active,” and the domestic market, from his standpoint, continues to be relatively strong for small to mid-size pavers. Fifteen- and 20-mile projects will still come along, says Bockes, but for the most part, smaller projects will be the norm.

“From what I’m seeing,” says Randy Bouillon, sales and application specialist at Power Pavers, “the market is picking up in some areas—contractors are looking at updating due to more profitable jobs becoming available, and because tighter specifications are requiring new or later-model equipment.”

Larry Eben, district manager, Terex Bid-Well Equipment, says that the federal government created a speed bump of sorts for the machine market late in 2013:

“The overall market had been slowly and steadily improving,” says Eben, “but the government shutdown and uncertainty at the federal level have increased uncertainty at state and local levels, which affects contractor confidence. Investing in equipment requires a certain level of confidence that projects will be available, and if that confidence is lacking, then there’s less incentive for contractors to invest in new equipment.”

Concrete paver innovation

Uncertainty in the market, however, seems not to be deterring manufacturers of mainline paving equipment from refining products for greater utility and a smoother end product.

Utility is the hallmark feature of the new Wirtgen SP 80i, which offers a three-configuration modular design: three-track (four optional) offset (SP 81i); two-track inset (SP 82i); and four-track inset (SP 84i). Options allow switching configurations, and SP 80i models can be operated via stringline or stringless guidance systems. In addition, says Tim Nash, director, concrete products in the Americas, Wirtgen’s Eco-Mode system matches engine output to the application, promoting engine efficiency, fuel savings and lower sound levels.

Guntert & Zimmerman’s Meskis calls the company’s new S850SL a “market conscious” machine, designed to accommodate bid requirements to minimize lane closures, a requirement that results in more single-lane versus dual-lane paving. The S850SL’s narrow-profile design, says Meskis, allows it to work with as little as 12 inches of track line, permitting “a mid-size paver to be used where it could not be used before.”

Also new for Guntert & Zimmerman is the EGON (Equipment Guidance and Operation Network) system, which adds remote interface and diagnostic capability to the company’s Plus+1 control system. If a system or component is operating outside set parameters in any of the EGON system’s seven controller groups, the information is immediately communicated to the customer and to Guntert & Zimmerman.

GOMACO’s proprietary G+ control system, designed by the company’s own specialists, has become available for nearly all equipment in the GOMACO line during the past year. The G+ control panel’s “run” screen illustrates various machine aspects, including leg position, paving speed, drive percentage, steering parameters, grade information, and deviation meters. The system also features a detailed fault history with time stamps and date information.

Complementing the G+ system is the new G+ Connect system, a proprietary CAN-based network communications system that allows rapid, two-way communication between all accessories and the G+ controller, with the result, says GOMACO, of “tighter, faster, and more accurate machine corrections.” The G+ Connect system is designed to permit all components of the paver to be easily interfaced, simply by “connecting” such items as a 3D stringless guidance system, dowel- and tie-bar inserters, power transition adjusters, or the GOMACO Smoothness Indicator (GSI).

The GSI is a non-contact measuring unit that provides on-the-go surface-profile checks by tracing the slab and taking readings, simultaneously, from three different sensors on each trace. Readings can be reported in multiple indexes, including the GSI number, International Roughness Index (IRI), and Profile Index (PI). The data also can be exported to support other indexes. According to GOMACO, the GSI allows immediate adjustment of the paving process, if required, and is being used increasingly on overlay projects.

Concrete paving innovation

Among the techniques gaining wider use in concrete-pavement work are overlays, two-lift placement, and stringless paving, the latter, especially, as employed on overlay projects.

Overlays generally are classified as bonded or unbonded, the former typically ranging in thickness between 2 and 6 inches and used to add structural capacity and/or to eliminate surface distress for existing pavements in good condition. Unbonded overlays might range from 4 to 11 inches in thickness and typically are used to rehabilitate pavements with some structural deterioration.

Overlay design, however, says Robert Rodden, the ACPA’s director of technical services and product development, is not about selecting one type or the other, but about “looking at the existing pavement—whether asphalt, concrete, or composite [concrete with an asphalt overlay]—and determining which option is best suited, given the condition of the pavement.” A number of design methodologies are available for calculating the required overlay thickness and other parameters.

Concrete advocates make the point that overlays conserve the equity in the existing pavement, and that, based on equivalent design life, concrete overlays compete favorably with asphalt on both life-cycle cost and initial cost. In addition, an increasing number of contractors are finding that stringless guidance systems bring greater efficiency to the overlay process, resulting in a smoother end product, reduced labor costs, reduced jobsite congestion, and optimum material conservation.

“With today’s demanding smoothness requirements on paving projects,” says Kent Godbersen, GOMACO’s vice president of worldwide sales and marketing, “contractors are always looking for more ways to improve rideability numbers, and stringless paving is proving a valuable tool for them.”

According to the ACPA’s Davenport, the industry also is showing a renewed interest in two-lift paving—the placement of two wet-on-wet lifts of concrete. This technique, he says, allows the use of less expensive or recycled aggregates in the lower lift, while saving the best aggregate and premium materials for the wearing course in order to minimize the effect of freeze/thaw cycles, improve skid resistance, reduce pavement noise, and prolong pavement life.

 
 

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