Curb-and-gutter machines vary mainly by size, and examining your applications is the first step in determining the right size machine for your jobs.
In the mid-1990s, manufacturers began making more models of mid-size curb-and-gutter machines, which weigh less than 10,000 pounds. “That’s given smaller contractors who would normally farm out this work the opportunity to purchase a machine for less money and be able to transport it with their existing equipment,” says Fred Russell, product manager, curb-and-gutter products, for Miller Spreader.
Steve Simons, marketing manager for LeeBoy, says another advantage of intermediate-size machines is their versatility. “This size curber can handle production such as subdivision work as fast as a larger curber,” he says. “In detailed parking lots, it has maneuverability larger curbers don’t have, which can eliminate much hand work.”
If you need a machine that can do everything from parking lot work up to pouring highway barrier walls, however, you’ll need a large curb-and-gutter machine, says Stephen Bullock, vice president of sales and marketing for Power Curbers. These machines are equipped with trimmers, which prepare the subgrade and can save you time in all your applications.
And features such as Gomaco’s all-track steer and all-track positioning make it possible for large machines to pour acceptable curb and gutter, sidewalks and barrier walls. All-track steer gives larger machines the ability to steer around a tight radius, rather than sliding on grade. When all tracks have the capability to steer, you eliminate the skid steer action through a radius and produce a high quality end product without continual manual adjustment of the machine sensors. With all-track positioning, the right-front track hydraulically extends and retracts and the rear track hydraulically sideshifts. Each leg has a reinforced steel attachment plate that allows extra leg height adjustment. All-track positioning provides the capability to perform various applications and work with differences in grade elevations and unique jobsite logistics.
Sales of small curb machines – those weighing less than 3,500 pounds – have taken off during the past two years as extruded curbs have become popular landscape borders. These machines can also cross over into parking lot work, laying tack-on curbs over asphalt, says Jeremy Garret, president of Tygar Manufacturing.
See the chart on page 86 for more information about different size classes of curb-and-gutter machines, their applications, attributes and price ranges.
TIP: Make sure the jobsite is completely prepared — grading finished, stringlines set and obstacles calculated — before the concrete arrives.
Tracks vs. tires
Tracks, which are generally found on larger curb-and-gutter machines, are less susceptible to ground conditions than tires. If you are working on a rough subgrade or with soil that’s sandy, muddy or contains a lot of large or loose rocks, you should use a tracked machine, Bullock says. “Anytime you’re pouring with a large mold like a barrier mold or a large sidewalk, I think you get more stability out of tracks,” he adds.
Russell says rubber-tire machines should be used only on a 90-percent-compacted base. The advantages to tires are they’re less expensive than tracks, are less likely to damage existing asphalt mats and provide a bit better maneuverability.
Training and operation
The biggest variable in pouring curb is the concrete mix, Bullock says. Work with an experienced concrete supplier who can give you a consistent mix from one truck to the next. “The mixer and the concrete are half the battle,” Russell says.
Make sure you set up the machine properly. Setup mistakes range from problems with the stringline to how sensors are mounted to the condition of the mold, Bullock says. Manufacturers or dealers usually send a technician to the jobsite when they sell a curb-and-gutter machine to teach the contractor’s crew how to set it up correctly.
Simons says training two employees – one as a chute man and one as the operator – is a good practice. Then cross-train the two and you’ll have backup in case of an emergency. “That experience and training will show in the quality and consistency of the work,” he says.
And remember operators switching from one size curbing machine to another will usually have trouble adjusting to the new machine. They will need to retrain and practice.
TIP: For long, generally straight pours a large curb-gutter machine will be more productive than mid-size units.
Preparing the site
Make sure the job is ready before you order concrete. Check grades and be ready to curb when the concrete trucks arrive. “You make money when you are efficient,” Simons says. “Be one step ahead and when the lines are set and pouring is occurring on one site, have someone at the next site making sure it will be ready for the curber to arrive and go to work on that job without missing a beat.”
While moving quickly is important, don’t continue to pour when you have a problem. Stop, fix any grade, line setting, mix or equipment problems and then proceed. Simons says it’s a good idea to do a 100-foot dry run and make sure the curber is working properly before the concrete truck arrives.
Have the right tools on the job and know what the job requires before it begins – whether you will be cutting joints or using felt in joints and how they will be spaced.
When using a small machine to pour a lot of contours, use a stringline and tape measure to make sure all the dimensions are equal, Garret says. “I think layout is the most important part of the whole application,” he says. “If you get that done correctly, then the rest will flow smoothly.”
Russell says the most common mistake he’s seen is operators increasing vibration when material stops coming out of the machine. “The tendency is to turn it up,” Russell says. “But the reason that material stops coming through is because it’s compacted into the machine. Increasing vibration compacts it even more. They need to decrease the vibration and physically drive the material through the machine.”
Keeping it clean
The lifecycle of a curb-and-gutter machine depends largely on how well you keep it clean, Russell says. If the concrete hardens and you have to hammer it off with a chisel, there’s a good chance you could damage the machine. “Between loads while you’re waiting for another truck, just go around and knock some of the slop off the sides,” he says. “Concrete’s a lot easier to remove while it’s still wet. Once you’ve cleaned it off the hard way one time you kind of remember to keep it rinsed off.”