Following its introduction in the late 1940s, slipform paving literally revolutionized the way concrete was placed. Nearly 60 years later, it is now the standard for most large concrete paving jobs. Yet, it is also finding increasing use on small or tight-radius pours thanks to advances in paver designs and mold configurations. Even some larger pavers are finding a place on projects once relegated to screeds and forms.
The biggest benefit to slipforming is clearly its ability to reduce or eliminate hand labor. "The cost differential is dramatic," says Tom Zignego, president, Zignego Co., Waukesha, WI. "The machine work is probably a third the cost of the hand work."
Although it performs many large interstate projects throughout southern Wisconsin and northern Illinois, Zignego Co. also works with municipalities to complete street work and other smaller jobs. For these projects, it uses its two GOMACO Commander III curb and gutter machines whenever specs and jobsite conditions allow.
Metro Pavers in Iowa City, IA, has a similar philosophy toward its paving projects. The contractor uses three Power Pavers slipformers for jobs such as development and city work, medium to large parking lots and even county secondary roads. "We use them wherever we need them," says Nick Kempf. "We might go out and pour a 400- or 500-ft. street, then go pour for three days on one job.
"You still have to build intersections and tie in streets," he adds. "But we try not to. We try to do slipform."
Adapting to the application
Intermediate pavers typically deliver maximum paving widths anywhere from 18 to 24 ft. Though they are frequently used to pave a set width throughout the work day, this is not always the case. As such, manufacturers are making it easier and less time consuming to change from one width to another.
"It's very easy to change the machine — to put 1 ft. in or take 1 ft. out," says Kempf of the Power Pavers units. "If you're just moving it a foot, you can do it in a few hours."
The telescoping frame on GOMACO's GP-2600 paver extends on the left side, providing widths from 12 to 18 ft. 6 in. And the GHP-2800 allows for widths from 12 to 25 ft. with no frame inserts added. "It's a matter of selecting the right machine for your paving projects," says Kent Godbersen, GOMACO's vice president of worldwide sales and marketing. "If you're doing mainline paving, you need the size, weight and horsepower to work with the concrete volume at 24 ft. wide or wider."
For those seeking even faster width changes, Terex Roadbuilding offers its TEREX/CMI SF2204B HVW (hydraulic variable width) paver. These premium units can adjust from a roughly 8.5-ft. transport width to a 20- to 22-ft. maximum width in under an hour.
"The tractor and paving kit, along with the plow and final finisher, are all variable width — it's all done in unison without disassembly," explains Tom Devonshire, product manager for concrete mobile products, Terex Roadbuilding. This gives you the luxury to pave several jobs of varying widths in a single day, he adds.
Though the HVW design is not a new concept, some of the applications it is being asked to perform are. "What we're doing now is introducing the HVW into a new market segment. We want the contractor to know that he can utilize the HVW in several different applications — which include barrier/parapet, curb and gutter, specialty work, 10- to 12-ft. shoulders — with a specific kit that's available," says Devonshire. "Its versatility allows the HVW to be configured to meet the contractors needs, including mainline paving."
Paving kits and molds are enabling pavers in this class to engage in pours with more complex geometric designs. For example, the HVW machines are available with an offset mold that adjusts anywhere from 4 to 10 ft. incrementally; a median barrier and parapet wall mold for wall heights exceeding 42 in.; a kit for paving paths or shoulders from 5 to 12 ft.; and even a zero clearance kit for slipping shoulders right up against an obstruction.