Way to Pave
Showcasing the top trends and the latest equipment in concrete and asphalt paving
Whether concrete or asphalt, a recent Grading & Excavation Contractor survey indicated that more than 40% of its readers are either involved or interested in paving markets and equipment—topics not previously covered in the publication. Plus, with World of Concrete and CONEXPO-CON/AGG 2011 packing into the Las Vegas Convention Center this quarter, it’s high time to showcase the top paving trends and the latest equipment.
Paving industry trend hunters will hit pay dirt when examining recent projects at a couple of the nation’s busiest airports. Not surprisingly, airport paving jobs are all about timing, tight specs and traffic. Contractors must be willing, ready and up to the challenge of getting it right the first time. One of the top trends in the concrete arena is best illustrated by recent work at the Charlotte Douglas International Airport in North Carolina where a stringless paving system was used for speed, accuracy and ease of access within the job site. With the use of stringless technology, the contractor saves money by eliminating or minimizing surveying, stake driving, and string setup.
Approximately 55,000 tons of P-401 WMA was installed during a runway project at Logan Airport with equipment including a Caterpillar AP1055D asphalt paver and a CAT CB534D XW asphalt roller.
Hilliard, OH–based Hi-Way Paving was the prime contractor for the Phase Two package of work at Charlotte Douglas. Concrete paving work included the new 9,000-foot runway; two taxiways that were 4,500 feet and 4,800 feet in length; high-speed crossovers; and four large connectors that tie into the existing runway. Approximately 242,500 cubic yards of concrete was slip-formed, all with Gomaco paving equipment.
Hi-Way Paving brought in its Gomaco four-track GHP-2800 paver, PS-2600 placer/spreader, and T/C-600 texture/cure machine. With round-the-clock operation required, the company added a new two-track GHP-2800 and PS-2600. Crews could be paving with one train during the day while another crew could be setting up another train for a night pour.
New to Hi-Way Paving’s inventory for the airport project was a stringless paving system. The placer/spreaders were controlled by GPS units, while the Gomaco pavers utilized Total Stations for greater accuracy.
In fact, the entire project was stringless, including the 6-inch-thick cement-treated base (CTB). Approximately 85,000 cubic yards of CTB was laid to form a solid base for the new concrete.
Concrete for the project was mixed onsite with two 12-cubic-yard mobile batch plants. Dump trucks carried 10-cubic-yard loads of concrete to the paving site and dumped onto the belts of the PS-2600 units. On Hi-Way’s longer paving runs, both placer/spreaders were used in front of the four-track GHP-2800 to maximize production.
“From day one on this project, we used the stringless system,” says Kevin Stephen, job superintendent for Hi-Way Paving. “The first day was a little scary because we had nothing to check it to. We’re used to having a stringline there that we can measure from and see that everything is on line. We learned to check each day’s pour prior to paving day, just to make sure we didn’t have a bad grade. It helped us locate any bad spots in the CTB and that helped us avoid any bumps in the final concrete because of bad grade.”
The Total Stations from the stringless system helped Hi-Way locate the electrical cans in the concrete. A total of 3400 electrical cans were paved over in the runway. Electricians needed to find them and then core them out. The Total Stations were used to mark and locate each can so the light fixtures could be attached.
The new two-track GHP-2800 spent the majority of the project slip-forming the 700-foot-long high-speed crossovers. “The two-track is easy to get in and out of those short paving runs, and allows us to pour closer to the joints,” says Stephen. “A second paving spread allowed us to have a crew getting the equipment in place for the night pour while we were paving on the runway during the day. We didn’t have any downtime at all.”
Time was critical for the crossover pours, which had to be completed at night, with the airport only allowing 5.5 hours of working time so the existing runway could be open again to plane traffic by 6:30 a.m.
“That was basically a project all by itself,” says Stephen. “We had a night crew working constantly. They slip-formed over 20,000 cubic yards of concrete, connecting the old runway to the new connectors.”
Very little finishing work was required behind the GHP-2800 pavers. Finishers used a 16-foot straightedge and the T/C-600 machine applied a burlap-drag finish.
“We are very pleased with the GOMACO equipment, and it just keeps getting better with the stringless aspect of it,” says Stephen.
Warm-mix asphalt (WMA) is a variety of technologies that allow the producers of hot-mix asphalt pavement to lower the temperatures at which the material is mixed and placed on the road. Reductions of 50- to 100-degrees Fahrenheit are typical, with the result of cutting fuel consumption and decreasing greenhouse gas emissions. Additional big benefits include better compaction on the road, an ability to haul paving mix for longer distances, and the extension of the paving season. For those new to WMA, more information can be found on the Internet at www.warmmixasphalt.com.
Aggregate Industries’ (AI) Northeast Region is in its fourth season of producing warm mix asphalt at its Saugus, MA–based plant. AI is definitely past the experimental stage with WMA, but as Kevin Riley, AI quality control manager, points out, “We are still learning about warm mix on every project. One of the best characteristics of warm mix that we’ve been able to confirm is how easy it is to compact.”
The largest WMA project for AI was at Boston’s Logan Airport. It involved the rehabilitation of Runway 9-27. Approximately 55,000 tons of P-401 WMA was installed during the project with an equipment fleet that included a Cat AP1055D asphalt paver and a Cat CB534D XW asphalt roller.
The product coming out of the Saugus plant is a Lime Latex RAP Warm Mix with a Sasobit Wax organic additive blended at a rate of 1.5% by weight of asphalt cement (AC) at the AI terminal. The job mix formula also calls for 15% to 20% recycled asphalt pavement (RAP) by total weight of the mix.
There are a lot of benefits to using this WMA recipe at Logan International Airport, says AI. The latex additive helps prevent rutting, which is a major concern on runways and taxiways. The hydrated lime is an anti-stripping agent. “We really like what lime does for us in many of our mixes,” reports Riley. “We find that lime helps stabilize tender mixes in addition to its anti-stripping quality.” He explains that the use of RAP reduces the environmental impact of the project and saves money. The addition of Sasobit organic wax additive ultimately allows for less compaction energy needed to consolidate the mat and reach high density. The cost of the admixtures (latex, lime, Sasobit) is offset by the fuel savings; and the reduction in demand for virgin asphalt cement is due to the high RAP content.
Aggregate Industries approaches quality control of warm mix the same as it would for hot mix. A quality-control technician is kept busy monitoring densities and temperatures using a calibrated electronic density gauge.
From the paving perspective, warm mix passes through the paver the same as hot mix in AI’s experience. If anything, the Sasobit helps move the latex-modified mix through the paver a little easier, according to Chuck Kapello, the crew mechanic responsible for maintenance and repair of equipment at the Logan project. He says that latex mixes put a lot of drag on the feeder system. “This mix is a little better, but we still use more fuel because more horsepower is used. We also heat the screed a little more to prevent dragging on the latex mix at the start,” he says. As to maintenance, Kapello says that throughout the shift more cleaning is needed because the mix is so sticky. “You don’t want any buildup in the conveyors or augers, and you definitely have to keep the end gates clean or they’ll hang up. The end gate skis can also get gummy. Every time we pick up and set back, we’re checking to see that nothing is getting hung up or has a big buildup of mix,” he says.
|Photo: Guntert & Zimmerman
Above: The S600 from Guntert & Zimmerman is one of the narrowest-profile machines on the market.
Below: Highway-class paver models from Roadtec are available with an optional temperature sensing bar.
It appears certain that warm-mix asphalt is going to be part of Logan’s ongoing maintenance and rehabilitation projects as WMA use is justified by performance, by diminished environmental impact, and by lower cost. Aggregate Industries’ Northeast Region has seen steady growth—from experimentation in 2006, to documentation of WMA performance in 2007, to producing around 90,000 tons in 2008 and over 100,000 tons in 2009. “We’ve put WMA down on interstates, on airport runways, on state highways, on city streets and on town roads,” reports Riley. “At various depths and using various additives, the application range seems to be very broad. We feel comfortable promoting and producing warm mix asphalt. Our experience at Logan tells us we’re making a good product”
Concrete Paver Showcase
Wirtgen America—The debut of the SP 15 and SP 25 concrete slip-form pavers marks Wirtgen Group’s entry into the North American concrete slip-form equipment market. “While North American customers readily associate Wirtgen Group products with asphalt and asphalt recycling, Wirtgen is a world leader in concrete slip-form paver manufacturing as well, with a pedigree that dates back nearly five decades,” says Wade Bowman, national sales manager, concrete slip-form pavers.
Bowman says that the SP 15 and SP 25 are true multipurpose machines that lay curb and gutter, barrier, sidewalk, V-ditch, special applications, and slabs. Both machines can be quickly configured onsite for left- or right-side pouring. What differentiates the machines, he says, is that each will pour more accurately and require less handwork than other machines on the market. “Each has best-in-class trimming capacity, unsurpassed job-site mobility, and pours the tightest, smoothest radius in the industry with all-track steering and positioning. The new units also feature an Eco mode, which matches engine rpm to machine power requirements for fuel savings and reduced emissions,” says Bowman.
As to stringless or GPS-based concrete paving, Bowman says that he doesn’t expect many contractors to use this technology right away for curb and gutter applications, but that it is definitely the wave of the future. “This technology is available for our machines as an option, and we are devoting the resources necessary to be a leader in this area,” he says.
Terex Roadbuilding—To be introduced at World of Concrete 2011, the Terex SF2204B HVW (hydraulic variable width) concrete slip-form paver allows contractors to spend more time paving and less time changing widths. According to Terex Roadbuilding, it is the industry’s first field-proven slip-form paver to adjust widths hydraulically. The new unit goes from its minimum 8-foot paving width to its maximum 20-foot paving width in minutes rather than hours. A “B Series” design includes an available 2-foot extension kit for 22-foot-wide paving.
The SF2204B design improves performance and increases reliability, while enhancing the serviceability of the HVW paver, says the company. A concrete pan profile length of 48 inches allows operators to achieve quality paving results when using commercial ready-mix concrete. Modified track frames enhance support, even in marginal trackline conditions. Two-speed, variable displacement drive motors deliver a 90-feet-per-minute travel speed to improve onsite mobility and productivity.
Power Curbers—Since 1985, Power Curbers has constantly developed and expanded its 5700 series. From its roots as strictly a curb and gutter machine, the 5700 has evolved into the 5700-C, a “one-machine-does-it-all” slip-form paver which handles sidewalk, V-ditch, and barrier walls.
In 2010, for the 25th anniversary of the 5700 series, Power Curbers added yet more capability to the 5700-C. The 5700-C with optional “Max Package” outfits the machine with larger crawlers, all crawler steering, and repositionable right post for pouring large variable barrier up to 8-feet high, paving to 12-feet wide, and other large applications.
Crawlers on the 5700-C-Max are one foot longer, heavier, and grow from three rollers to four for increased stability. The new low-speed crawler torque hubs keep the machine pouring at a steady crawl when handling large offset molds.
All Crawler Steering, a longtime option on the 5700-C, improves steering accuracy when paving, pouring large walls, and in other demanding applications.
The Max Package includes mounting plates on the machine’s right side to allow contractors to bring the right rear post forward. Bringing the leg forward redistributes weight, improving the machine’s performance when using large barrier molds and when paving in the center-pour position.
Guntert & Zimmerman Construction Division Inc. (G&Z)—The G&Z S600 Multi-Purpose Slipform Paver is designed with the mobility of a small paver, without sacrificing the same performance advantages contractors expect from G&Z’s large and mid-size pavers. The S600 is designed around a traditional slip-form paver tractor making it ideal for highway and airport paving projects. Featuring a double telescopic tractor frame, access walkway, and hose hinges for a nominal working range of 8 feet to 22 feet, 6 inches, with up to 7 feet of telescopic ability per side—the S600 offers the widest range in the industry, says the company.
The Multi-Purpose S600 is also designed to excel in alternate applications including barrier wall, offset paving, zero/minimum clearance paving, and canal paving. The versatility of the S600 tractor allows the contractor to quickly switch between applications and paving widths. The end bolsters are designed with universal bolting patterns offering a wide range of three- and four-track tractor configurations with or without swing legs. The S600 is one of the narrowest profile machines on the market.
The S600 is available with G&Z’s Compact Dowel Bar Inserter (CDBI). The patented CDBI is a single, self-supporting module that mounts quickly on the rear of the S600. The highly productive, mobile, reliable, and user-friendly G&Z CDBI is designed to insert dowel bars accurately, make width changes and transport easy, and achieve smooth rides.
Additionally, the S600 features G&Z’s NoLine: Stringless Paving Preparation Kit. NoLine integrates the use of stringless technology directly into the S600 Operator Console. With NoLine, there is no need for any additional technology other than the stringless system sensors to be mounted on the paver.
Gomaco—The new GP-2400 is an economical choice for contractors looking for a half-width concrete paver capable of slip-forming widths up to 24 feet in width. The GP-2400 is also designed to be tight-radius capable, user friendly, maneuverable, easy to transport from site to site, and quick to set up, says the company.
The new GP-2400 paver is the result of a contractor approaching Gomaco with a specific request for a new machine capable of slip-forming a tight radius. It’s equipped with 10-foot, Gomaco series-two tracks capable of turning tighter than traditional-length tracks on a paver. The tracks also allow for a minimum machine transport width of only 10 feet, making job-to-job mobility easier, safer, quicker, and more cost effective.
It is also equipped with the exclusive Gomaco G+ control system with self-diagnostics for grade and steering. The control system was designed in-house by Gomaco control specialists and features easy-to-operate hardware with steering and travel dials, while buttons are used to control elevation.
The paver features the Gomaco 3100 series open-front mold and a telescoping frame that provides extra versatility. The GP-2400 provides contractors with a range of paving widths from 10 to 16.5 feet with the standard telescoping frame, and paving widths up to 24 feet with frame inserts.
Asphalt Paver Showcase
Volvo Construction Equipment—Paving performance is increased with global technology utilized in the Volvo PF6110 tracked paver, according to the company. The auger system on the PF6110 is independent of the conveyor system. Each of the two auger and conveyor drives uses sonic sensors for more precise handling of material. The conveyor system has chains that are automatically tensioned for proper performance and less downtime. The conveyor chain cover cleans itself, providing easier maintenance. Reversible augers and conveyors are available as optional equipment.
Hopper capacity for the series is 14.4 tons, giving the paver a practical production rate of 820 tons per hour. The PF6110 paver has a screed width of 10 feet and a maximum paving width of 26 feet. A technically advanced, hydrostatic direct-traction drive system on the paver eliminates 70% of all mechanical drive train components to reduce maintenance costs.
The continuous and flexible rubber tracks on the PF6110 have larger, oscillating bogies that provide optimal ground contact and traction. A Blaw-Kote release-agent spray system is integrated into the machine, with a pushbutton operation, to keep the tracks clean and provide easier maintenance.
Caterpillar—The AP555E Asphalt Paver is a new addition to the Caterpillar Paving Products machine family. Caterpillar stresses its excellent mobility, superb visibility, powerful C4.4 engine, quick setup, and a comfortable operating environment as just some of its advantages.
The compact, lightweight design allows contractors to haul the paver along with other necessary job-site equipment, maximizing machine transport while minimizing costs.
The AP555E features include a Cat 4.4 engine with ACERT Technology, dual operating stations with the Advisor Monitoring System (AMS), tilting consoles, exclusive Mobil-trac undercarriage, high-capacity cooling system, belt-driven generator, and unique material-handling system with independent auger and conveyor controls.
The dual swing-out stations, tilting consoles, and low-profile design of the cooling system provide good forward visibility that enables the operator to communicate effectively with the truck driver while monitoring mix in the hopper. Extending the stations beyond the machine frame also enables good joint-matching capability and optimal rearward visibility to the auger chamber.
An advisor monitoring system located on the left operating station provides an interactive interface to assist the operator. The system includes project planning calculators, startup checklists, engine operating conditions, and many other features to assist the operator. The system also lists fault codes for machine functions, making troubleshooting quick and easy.
The material-handling system is one of the most advanced in the paving industry, according to Cat. Automated controls and well-designed components reduce segregation potential and maximize efficiency for higher mat quality. The system utilizes four individual pumps that enable each conveyor and each auger to deliver the exact amount of mix to the screed. The left and right conveyors, in addition to the left and right augers, are controlled independently, ensuring mix demand is met when increasing or decreasing paving widths. Ratio-control dials and sensors (mechanical or sonic) signal the augers and conveyors to run faster or slower when changing paving widths, thus keeping the head of material at the set level. When paving around obstacles the system automatically makes the necessary adjustments for uniform mix delivery.
Terex Roadbuilding—The Terex CR662RM RoadMix material transfer vehicle and paver is newly engineered with design enhancements that increase production and maximize utilization capabilities. The model features a variable-pitch in-hopper auger design that dramatically increases material throughput. Pitch spacing—transitioning from 10 inches in the front to 11 inches and then to 12 inches in the rear—aggressively channels material to the rear of the machine for faster truck unloading. This auger design helps boost production capabilities, which can exceed 500 tons per hour. Even with the aggressive pitch, the auger’s constant-diameter continues to reblend 100% of the material to combat both material and thermal segregation.
The CR662RM’s conveyor assembly features a stationary lift conveyor with flights averaging every other pitch to reduce hydraulic pressure and quickly channel material from the rear of the tractor to the swiveling conveyor. Hydraulic pressure gauges for the conveyors, mounted at the operator’s station, help to minimize the chance of plugging the system. Hydraulically operated clean-out doors and reversible conveyor flights help to clear obstructions.
Contractors making the investment in a material transfer vehicle are looking for maximum return on investment. According to Terex, the RoadMix delivers by substantially increasing machine utilization rates, since it works equally as well as a Remix Anti-Segregation System paver. The variable-pitch, in-hopper auger design enables the CR662RM to match or better production rates of conventional slat pavers, while giving the additional benefit of virtually eliminating segregation.
Roadtec—Roadtec announces technology upgrades to its five models of highway class pavers. The new Roadtec Screed Boost is designed to increase mat smoothness. While Screed Assist has been a staple in the industry for some time and simply helps to support the weight of the screed whether the paver is moving or stopped, the exclusive Roadtec Screed Boost is an additional option that manages the settling of the screed only when the paver is stopped. The feature also compensates for settling of rubber-tired pavers during stops, caused by the tires compressing and “squatting.” Rubber tire compression causes the screed to descend and has led some in the industry to conclude that it is more difficult to get the same mat smoothness from a tire paver than a track paver. Screed Boost effectively addresses this issue giving road builders the tools to pave even, smooth mats with both types of pavers.
Additionally, all Roadtec highway-class paver models will now be available with an optional temperature sensing bar which measures the temperatures of the entire mat width in real time and records that data, along with the corresponding GPS coordinates. Even temperature leads to even compaction and density, which minimizes future pavement failures.
Author's Bio: Construction writer Carol Wasson is a frequent contributor to Forester publications.