Bucking a Trend

Paving Article August 06, 2001
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While the general economy struggles, the concrete paving market is cruising, if Bid-Well and CMI are any indication


While the general economy struggles, the concrete paving market is cruising, if Bid-Well and CMI are any indication.


"I’d say we’re up probably 20-30% over last year and over 1999, which was a fantastic year," Jack Lease, vice president and sales manager at Bid-Well, told ROADS & BRIDGES. Most of Bid-Well’s business growth is in concrete pavers that are used on bridges.


The main reason for the relative health of the concrete paver market seems to be that the Transportation Equity Act for the 21st Century (TEA-21) is finally reaching fruition. It took a few years for construction projects to go through the design process, but now the actual construction is ramping up.


The first surge of money has gone to reconstructing bridges. As a result, Bid-Well, a Canton, S.D.-based division of CMI Corp., is doing well with its core product line of bridge pavers.


"The majority of the states now have their matching funds in place," said Lease, "so they can do some infrastructure work." And there are plenty of U.S. bridges that need rehabilitation.


Even paving of mainline highways between bridges is starting to pick up speed. "Concrete paving is definitely in a growth posture," said Chapin Sipherd, product manager for concrete paving and trimming at CMI Corp., Oklahoma City. "Mainline paving has been marginal for everybody in that business from a manufacturing standpoint."


Sipherd told ROADS & BRIDGES that the concrete paver market was also benefiting from the increase in costs for asphalt pavement materials. The cost of oil is up, so the cost of asphalt cement, which is derived from oil, also is up. The increase puts the cost of a stretch of asphalt highway roughly equal to the cost of an equivalent stretch of concrete highway, according to Sipherd.


"So now the life cycle costing becomes a true factor," he said, "and the longer life of the concrete pavements is helping to drive the market."


An innovation on Bid-Well’s pavers is intended to extend concrete pavement life even further. Bid-Well’s patented Rota-Vibe is a vibratory mechanism that fits between the paving machine’s augers and the paving rollers and compresses the concrete as it is spread. The higher density of the concrete produces pavement that is more resistant to corrosion and moisture infiltration.


"It also improves the wearability and the life of a bridge deck," said Lease. "It improves the overall life-cycle cost analysis. Consequently the life of your bridge deck becomes longer."


For example, Bid-Well’s 3600 roller paver for bridges and other slabs has a traveling carriage-mounted longitudinal strike-off that passes back and forth across the pavement while the machine as a whole travels on rails in the direction of traffic flow on the road or bridge. The carriage combines augers, dual Rota-Vibe units, paving rollers, a drag pan and a texturing unit.


The machine paves a variety of surfaces, including matching flat, parabolic, crowned, skewed, super-elevated and tapered surfaces. The crown of the pavement can be adjusted at any hinge point or at any travel rail adjuster.


The Model 3600 paver features automatic machine operation and automatic machine advancement at the end of a paving carriage pass. The machine has a standard 36-ft paving width. By adding inserts, the 3600 can pave a 90-ft path. The machine is powered by two 20-hp gasoline engines or optional diesel engines.


The Bid-Well Heavy Duty 5000 paver features automatic machine operation, dual chain drive, dual augers with double flighting, dual Rota-Vibe, dual paving rollers, dual adjustable drag pan and an automatic dual spud vibrating system.


The 5000 paves airports, highways, streets, canals, slopes and other slabs, and it matches flat, parabolic, crowned, super-elevated and tapered surfaces. The adjustable tubular frame on the 5000 paver spans the concrete and rides on pipe rail or a form. The traveling paving carriage vibrates, strikes off, paves and textures the concrete. The new, improved spud vibration system is mounted on the paving carriage and consolidates the concrete just ahead of the paving augers.


This paver features CMI’s Hydra-Mation stringline sensing system and hydraulically powered leg screws for elevation control. Hydra-Mation is an all-hydraulic system for elevation and steering. It makes use of a patented hydraulic servo valve connected directly to the cylinder in the control circuit for elevation and steering. The system is reliable, accurate and not affected by humidity, dust or temperature, according to CMI.


CMI also is enthusiastic about its hydraulic width adjustment system, which allows the operator to change the width of the concrete pavement while in motion. The mechanism was introduced last year on the company’s Hydraulic Variable-Width (HVW) line of slipform utility pavers, the Model 2000 series. The width adjustments are helpful in paving different geometries.


The HVW pavers can complete a 1-ft adjustment in paver width in just two minutes. The end frames and track assemblies of the machine move telescopically out, pulling two paving molds into a new position.


It is not necessary to take the weight off the tractor to change the paving width. The widening operation can be effected by moving the machine, using steering and swing leg characteristics.


Powered by the choice of either a 150-hp or a 240-hp diesel engine, the 2000 Series HVW pavers feature hydrostatic ground drives that deliver steady motive power. Rigid, telescopic tubular weldments—supported with brass bearing plates for smooth travel—form the basis of the variable-width design of the pavers. Paving width is fully adjustable from one-half to full width using hydraulic frame widening and dual-element paving systems.


The 2000 Series HVW pavers are available in three- and four-track configurations, with paving widths of 8-20 ft, 10-28 ft and 10-32 ft.


Crowning on-the-go


The wrap-around console of the 12-27 slipform paver from Allen Concrete Pavers, Paragould, Ark., allows for easy operation of the 16-in. direct-drive split-reversible augers, hydraulic vibrators and power "on-the-go" crowning, according to the company.


The hydraulic belt finisher with oscillating motion helps to eliminate any imperfections that may exist behind the paving pan and decreases labor behind the machine.


The 12-27 slipform paver is ideal for streets, parking lots, shoulders, ramps, approaches, airfields and "whitetopping," according to the company. The machine has a paving width of 12-27 ft, an "on-the-go" power crown feature that is controlled from the operator platform and curb molds on the left and right. The machine’s two crawler tracks are 11 ft 11 in. long and 12 in. wide.


The 12-27 is capable of a paving speed of 21 ft/min. and a travel speed of 36 ft/min. It is equipped with a 240-hp diesel engine and four hydraulic stringline sensors.


Mid-sized workhorse


The S850 slipform paver was designed by Guntert & Zimmerman Construction Division Inc., Ripon, Calif., as a mid-sized machine with the versatility to do multiple functions, so the contractor needs fewer specialized pavers.


With the S850’s JC Frame Extension system, the width of the tractor frame can be changed from 34 ft down to 18 ft in order to go from traffic-lane width to ramp width in less than an hour, according to the company, using a truck crane or front-end loader to handle the 800-lb extensions.


The ability of the S850 to walk 90û with the flip of a switch allows fewer and shorter hand pours and allows for maneuvering in tight confines even under urban traffic conditions and with minimal disturbance to the motoring public.


To help protect the tractor structure from high stress, the S850 comes standard with a self-leveling feature. When the machine is being moved, the operator can turn on the self-leveling feature, which automatically keeps any twist out of the machine and protects it from damage in transit.


The S850’s standard spreader plow has its own dedicated closed-loop hydraulic circuit that delivers the power needed to move big piles of concrete. It also allows easier access to clean the machine’s liquefaction hopper, with no gearbox or central auger bearing to impede the flow of concrete across the front of the machine.


Next-generation paver guidance


The new generation of Commander III slipform pavers from Gomaco Corp., Ida Grove, Iowa, provides greater versatility, according to the company, with three- or four-track operation and interchangeable molds for curb-and-gutter, sidewalk and barrier work.


Track circuits provide up to 44 ft/min. operating speed and 97 ft/min. for jobsite mobility.


Stringless guidance technology, 3D control systems and laser technology are available on the Commander III. These systems interface with the machine’s G21 digital operating system. The G21 system offers push-button steering setup and trainable track steering when interfaced with the "smart" cylinders. Software for the slope transition system provides automatic grade elevation correction and automatic steering correction, while eliminating stringline adjustment.


The Commander III features all-track steering in the operator’s choice of five modes: stringline steer mode; coordinated steer; crab steer; front steer only; and rear steer. Coordinated steer mode, in which the leading tracks turn in the direction of motion and the trailing tracks turn in the opposite direction, yields the smallest turning radius. In crab steer mode, all tracks turn in the same direction to walk the machine to the side.


Hijacked!


Four pedestal cylinders lift the Town & Country I Slipform Paver off grade for faster width changes, loading and unloading and for easy cleaning and servicing. The cylinders can raise the paver up to 50 in. for loading with the tracks on.


The Town & Country I from RexCon, Milwaukee, a division of Rose Industries Inc., paves to 20 in. deep in standard widths from 12 to 25 ft. With extensions, it can pave to 34 ft wide. A 325-hp engine powers the various hydraulic functions. Maximum travel speed is 45 ft/min.


Hydraulically operated edge wings control the surface at the pavement’s outer edge, maintaining a consistent edge despite variations in depth or slump.


A positively locking jackscrew system maintains the specified crown and prevents drift. The crown setting is simple to adjust, and the crown gauge can be read from ground level.


To change paving width, the Town & Country I relies on hydraulically driven, synchronized jackscrews to extend the frame equally on both sides. There is no need to add frame manually when changing widths. The 20-in.-diam., heat-treated auger and strike-off telescope as the machine frame changes width.


A screed alone


For jobs that don’t need a big paving machine attached to the screed, Metal Forms Corp., Milwaukee, offers heavy-duty and lightweight vibratory strike-off machines for concrete finishing and paving on streets, highway ramps and airport taxiways.


The Speed Screed models feature "double life" reversible finishing tubes that are easily reversed when the original wearing surface needs replacing. The finishing tubes are 3-in. x 3-in. aluminum tubes with a 1/4-in. wall.


The machines have self-contained power sources and may be propelled forward by either hand winches or hydraulic power winches. The screeds also quickly adjust to variable-width pours with easy-to-assemble 1 1/2-, 5- and 10-ft sections.


Turnbuckles with lock nuts provide fast adjustment for various crowns and slopes. Strategically located eccentric weights supply even vibration over the entire length of the pour.


Take a curb along


To finish off the paving on a street or through a housing development or to create a barrier or bridge parapet, the 5700-B slipform machine features a fully enclosed auger conveyor for increased mixing power and 18 cu ft of carrying capacity in the auger and mold, a quick-connect mechanism for changing molds, a network controller with slope compensation for mold speed control during tight radius work and a trimmer that adjusts 16 in. vertically and 80 in. from side to side.


The vertical adjustment allows the trimmer to be picked up at catch basins or other obstacles. It can be carried under the machine with no disassembly. The 80-in. horizontal adjustment is designed to trim and pour around 5-ft radii. It can trim up to 40 in. wide in the standard offset position. With trimmer extensions, it can pave up to 78 in. wide.


The mold offset can be hydraulically adjusted 24 in. horizontally and 16 in. vertically for flexibility on reconstruction work. The mold offset can be manually adjusted another 9 in. vertically.


The 5700-B curb and gutter and barrier/parapet machine is available from Power Curbers Inc., Salisbury, N.C.


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