Breaking Rocks and Other Hard Stuff
For a contractor involved in C&D work, the challenge is to choose the right machine for a particular job, and to stay abreast of further improvements in technology.
The Tennessee governor’s mansion was built in 1929 and acquired by the state in 1949. With little updating over the years, it became increasingly dysfunctional. Now a $10 million rehabilitation is under way to modernize the mansion and make it handicapped-accessible.
As part of this project, an elevator was installed recently in a part of the building that lacked a basement. To dig an elevator shaft without shutting down much of the mansion, True Line Coring & Cutting Inc. of Nashville, TN, used remote-controlled robotic machines from Brokk Inc. in Monroe, WA, the US subsidiary of Brokk AB of Skellefteå, Sweden.
“The dirt was very hard,” says Ron Dailey of True Line. “The only other way to do it would have been manual labor.”
Dailey’s solution is just one example of how construction and demolition technology for reducing hard substances—including rock, concrete, brick, asphalt, and metal—into pieces of smaller and more manageable size has advanced since the days of the pickaxe and sledgehammer. Machines now exist to break, crush, cut, grind, hammer, plane, pulverize, screen, shear, shred, and split such materials.
Some of these machines are attachments to excavators or other multipurpose machines; others are self-contained. The breaking mechanism may be an impact ram (which in essence is a giant jackhammer), a hydraulic piston-and-wedge assembly, mechanical jaws and teeth, or a grinder.
For a contractor involved in such work, the challenge is to choose the right machine for a particular job, and to stay abreast of further improvements in technology.
Henrik Sundgren, US sales and marketing director for Brokk Inc., explains that Brokk concrete breaking machines come with “a multitude of purposely built attachments, including breakers, concrete crushers, buckets, steel shears, grinders, scabblers for trimming surfaces, and even grapples for soft demolition. We also create special-purpose attachments on request.”
Brokk markets four different remote-controlled, electrically powered concrete breaking machines, ranging from the 4-kilowatt, 860-pound Brokk 40 with 100 foot-pounds of hammer pressure to the 30-kilowatt, 10,200-pound Brokk 330E with 1,200 foot-pounds of hammer pressure. The largest Brokk also comes in a diesel version.
“Our equipment is an investment, but it is also extremely productive for a contractor with the right type of projects,” Sundgren says. “The main benefit with using Brokk is that the machine is very small, lightweight, and electrically powered—perfect for confined-space demolition. Typical Brokk projects involve renovation of hospitals, schools, shopping malls, parking garages, and nuclear facilities where you don’t want to send a man into a contaminated area. The Brokk is remote controlled from a couple of hundred feet away, which makes it safe for the operator to use.” After the 9/11 terrorist attacks, US contractors used Brokk machines at the Pentagon and in the World Trade Center subway tunnels.
The machines require 480-volt, three-phase power. If the work site doesn’t have such a power supply, contractors typically bring in a mobile generator.
Brokk robots originated in Sweden in 1976 and first entered the US market in the late 1980s. Today, Sundgren says, the firm is a worldwide business and has about 500 US customers.
“Our machines became more sophisticated and better through the years,” he says. “Today they have digital controls. The operator wears a harness with a lightweight control box with two joysticks, one in each hand, to control the movements of the machine. It may sound sophisticated, but it’s really easy to learn.”
Brokk’s future machines will have even more attachments than today’s, Sundgren says. For example, Brokk recently introduced a remote-controlled battery-powered dump cart. “You would break the concrete with our machine, switch to a bucket attachment, load the debris into the electric cart, and roll out the debris,” he says. “Doing it that way will be safer and more efficient than using a skid-steer, wheelbarrows, and manpower.”
Photo: EJE Recycling & Disposal
Brokk machines are standard equipment for many contractors in Europe but are often viewed as a niche product in the US. “Some contractors, such as Ron Dailey’s True Line, were among the earliest adopters and have made valuable use of their Brokk machines,” Sundgren says.
“The European construction market today is more equipment-oriented and less manpower-oriented than the US market,” he observes. “Partly this has to do with labor cost and regulations. In the future we will try to further improve the contractors’ utilization of our equipment by becoming even more user-friendly and by offering more multipurpose attachments. If you make something that is intelligent, I believe you can make it easy to use as well.
“If you want a full-service business, use our machine in conjunction with an excavator or skid-steer. Brokk is not a machine to replace current equipment in your fleet. Rather it’s a machine that adds and expands services to your current equipment fleet.”
Where blasting, noise, and vibration are not acceptable, hydraulic splitters can be used to break rock and concrete. Elco International Inc. of Elmwood Park, NJ, is the US importer for a line of such equipment made by Darda GmbH of Blumberg, Germany. Russ Langfield, Elco’s president, says splitting also is the solution for rock so hard that even demolition hammers bounce off of it.
“You drill a hole 26 inches deep and 1.75 inches in diameter, and you put the splitter in,” he says. “It works with 400 tons of force to tear rock and concrete apart. It’s a tremendously powerful tool, operating at 7,200 pounds per square inch on a gallon and a half per minute of hydraulic oil. Ninety percent of the time it is used with an air compressor, but you can also use it with an electric pump for interior work, or with a gasoline-driven pump if air and electricity aren’t available.”
The splitter is made of aluminum and weighs about 70 pounds. It consists of inner and outer cylinders, and a piston with seals in the upper cylinder that moves a plug in the lower cylinder. A single lever atop the tool operates the piston, driving it down into the lower cylinder and sliding the tapered wedge of the plug between two feathers. As the feathers spread, their horizontal force splits the rock.
A splitting cylinder with a power unit and a 30-foot-long hose costs about $15,600; additional cylinders cost about $12,000 apiece. A single power unit can operate up to four cylinders at a time. “To speed up the process, we normally run two power units with four cylinders,” Langfield says.
Elco also sells Darda-made hydraulic crushers and shears for breaking concrete and cutting rebar. The smallest such products, Langfield says, “weigh 300 pounds to 1,000 pounds and mount on the stick of a mini-excavator to work in stairwells, under concrete overhangs, anywhere you need to get into a tight corner and can’t have noise or vibration. The entire unit is freewheeling so it can rotate 360 degrees. It turns to grab whatever it has to grab. Then you hit the hydraulics, and it closes to crush what it’s holding.”
Although handheld crushers exist, “They really haven’t taken off,” Langfield says. “The future is in boom-mounted crushers.”
Giberson Enterprises LLC in Shamong, NJ, sells the Eco-Crusher, an excavator-mounted bucket with a set of manganese jaws. It can crush concrete, brick, asphalt, and even soft rocks such as Florida’s coral rock and Hawaii’s lava rock.
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Casey Reed, southern US sales manager, says the Eco-Crusher is ideal for demolition and excavation contractors. “If you’re breaking up a concrete roadway or curb, you might pay a driver to take it to a landfill and dump it, have it crushed to the size you want it, and then have to buy that crushed product back,” he says. “With our Eco-Crusher, you bring the bucket onsite, reduce permit issues for noise pollution and dust, and eliminate transportation, tipping, and buyback fees.
“You could spend $25 to $30 a ton for tipping, hauling, and repurchasing crushed product. Using the Eco-Crusher onsite costs just $2 to $5 a ton.”
The Eco-Crusher produces material of a size the operator can specify, from 1 inch to 6 inches in diameter. The machine comes in three sizes, priced from $64,000 to $98,000 and ranging in weight from 5,000 pounds to 10,800 pounds, to fit excavators ranging in size from 30,000 pounds to more than 150,000 pounds.
“Depending on what you’re crushing and what size you’re crushing to,” Reed says, “the productivity of these machines ranges from 15 tons to 90 tons an hour.”
Another benefit of the Eco-Crusher is its ability to strip concrete from rebar so the rebar can be separated from the crushed material and sold as scrap. “If the bucket ever jams with rebar or a hard piece of metal you don’t know is there, you can tip it upside down and it will unjam itself,” Reed says. “With a big $500,000 track crusher, getting it unjammed would take hours’ worth of downtime.”
Giberson Enterprises is an offshoot of Giberson Plumbing and Excavating Inc., which Larry Giberson and his father Richard have operated for more than 30 years. Larry discovered the Eco-Crusher in March 2005 at the CONEXPO-CON/AGG trade show in Las Vegas, NV. He was on his way to buy a different crusher when a shuttle bus dropped him off in the wrong place—in front of the Eco-Crusher. Meccanica Breganzese srl makes the Eco-Crusher in Vicenza, Italy, and has sold more than 1,300 of the machines in Europe since 2002.
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Larry wrote the Meccanica Breganzese salesman a check on the spot, and put the machine to work in his own excavating business. Two months later he traveled to Italy, visited the factory, and established Giberson Enterprises to become the Eco-Crusher’s sole US distributor. Reed says US customers already have purchased more than 40 Eco-Crushers.
One of those customers, EJE Recycling and Disposal Inc. in Greenville, NC, uses an Eco-Crusher on a Daewoo 290 excavator to crush concrete that comes to its landfill. “We’re crushing 30 to 40 tons an hour to a two-inch-minus size for our general purposes, as the first application on a new road,” says Judson Whitehurst of EJE.
“The North Carolina Department of Transportation has shown interest. They’re stockpiling curbs and gutters—long, thick pieces that fit really well in the bucket, with enough gravity weight to push it on down.”
To adapt the Eco-Crusher to the US market, Larry developed the Giberson hitch, a universal coupler that attaches the machine to the stick of any excavator. “Stick lengths and pin widths vary with every make of machine,” Reed says, “so this new design allows us to custom-fit the bucket to a customer’s needs before delivery. When we deliver a bucket we include the custom hitch, hoses, and four hours of hookup time. We can also help with specialty hitch designs for customers with a certain style of coupler or hookup.
“We’re also developing a magnet attachment to catch the rebar before it gets out and falls on the ground.”
A Loader Crusher
Construction Technology Inc. of Noble, OK, does business under the IronWolf brand, producing cutter heads that are mounted on a wheel loader and driven by an auxiliary power pack hung off the back of the carrier machine.
The IronWolf Crusher is designed to process rock, concrete, and asphalt in the ground or in aboveground piles, says Jay Baker, regional sales manager. “We can replace ripper cats, hoe rams, dynamite, and rock crushers. The IronWolf Crusher sizes material down to a 4-inch-minus product,” he says. “In some applications, that material can be used as base fill on the same job site, if you’re constructing a road or a building site pad. Otherwise, it can be hauled off and stockpiled for use on another site.”
The IronWolf Crusher comes in various sizes. The smallest has a cutter head 5 feet wide, a drum 40 inches in diameter, and a $236,000 price tag. The largest has a 10-foot-wide cutter head and a 48-inch drum and costs $465,000.
“The IronWolf prototype is about 20 years old,” Baker says. “Larry Beller, our vice president, built the first ones in Prudhoe Bay, Alaska. He used milling drums and had augers on them, which doesn’t work in our application. At first we didn’t know we had a rock crusher. We were just flattening out the top of forestry roads. That began to change in Montana in 1990.
“Now we have three different patterns of teeth, trying to hold a rock in place. Instead of milling, we suck a round granite boulder 10 to 14 inches in diameter into the housing. The teeth hold it in position and bash it against breaker bars. We can mill, but also take in and process loose rock.
“The machine now has three fracture boards, one at the leading edge where the teeth enter the housing, the second at the quarter point, and the third at the halfway point. After the third, the rock falls free.”
Other modifications include the housing, which has opened from 1 inch to 6 inches. Internal protective plating has been added to protect the mild steel shell of the housing, and a replaceable wear point has been provided.
“We’ve gone through different planetaries and hydraulic pumps, bigger and better radiators, and Caterpillar engines that changed from Tier One to Two to Three for pollution control,” Baker says.
“We’re more efficient than most; plus we make usable gravel. It beats hauling the rock out in big chunks and then hauling fill in.”
Slashing Stuff in OK City
IronWolf also sells the Slasher, an evolution of the Crusher that can be mounted on a bulldozer. In addition to crushing rock, the Slasher will shred timber into a mulch that is used in Canada’s far north as a base for winter ice roads. In the spring it thaws and decomposes into the underlying permafrost.
The Slasher employs different drums. A door replaces three-eighths of the front of the housing to expose the teeth, and a pushbar bends trees and directs their fall.
The Slasher was used recently to demolish an apartment building in Oklahoma City, Baker says. “It was mounted on a wheel loader. The operator reached the cutter head up as high as the lift capacity of the loader—15 feet to 25 feet high—and set it down on top of the building. Then he just chewed it up. The Slasher shredded everything, even black inch-and-a-quarter gas piping, bathtubs, hot-water heaters, fan motors, ductwork, and all kinds of metal, as well as insulation.
“With an excavator, you would just claw the building into very large chunks. The Slasher was able to size it down significantly and put more tonnage in each haul-truck load.”
Baker also recounts the use of a Slasher to demolish a laundromat. “A lot of copper wound around the drum,” he says. “The operator was able to capture that and recycle it. Otherwise, it would have gone to the landfill.”
Another Loader Attachment
The Fahr Roadcrusher—another specialized loader attachment—can continuously process rocks, asphalt, and concrete on a road surface.
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Brian Bouley, marketing manager of Fahr Industries Inc. in Stateline, NV, says the $250,000 device “takes big rocks and makes them into smaller rocks” using a solid rotor with hammers mounted beneath it that pulls the material being processed up against a stationary anvil.
“It picks the material up off the ground,” he says. “The material goes over the top of the rotor and spins back down on the ground on the other side, a foot and a half from where it was originally. The federal government likes it because it doesn’t spread native seed material from region to region.”
To resurface a road, the operator simply rips up the old road, windrows the material into a continuous pile, and crushes it with the Roadcrusher. “He’s recycling the road without having to bring in new material and create new borrow pits,” Bouley says.
The Roadcrusher evolved from a European agricultural rock crusher that Bouley’s wife, Corinne Micheletti, brought to Canada in 1989. Refinements to the Roadcrusher over the years include thicker interior wear plates, stronger steel, and improved engine mounts. “Every year we send a questionnaire to our clients for ideas to improve the product,” he says.
In 1995 the US Forest Service purchased the first operational Roadcrusher, which reconstructed a stretch of road in Arizona. The project was budgeted for $3 million but cost just $300,000. The machine also has been used in a rails-to-trails project that converted an abandoned railroad right of way into a pedestrian and bicycle path.
Hammers and Crushers
UB Equipment Corp. in the Los Angeles suburb of Baldwin Park, CA, makes hydraulic hammers and crushers that attach to an excavator, backhoe, or skid-steer. Charles Min, the firm’s president, says his equipment sees extensive use in downtown Los Angeles as older structures are demolished to make way for new ones.
UB’s hydraulic hammers to break down a concrete slab or footing have an enclosed bracket design that eliminates bolt breakage, and replaceable tool bushings. They are nitrogen gas–assisted, enabling them to deliver faster blows. “Over the past 10 years,” Min says, “we’ve come up with a new user-friendly and equipment-friendly design—a polyurethane cushion device cradling the hammer—that reduces the stress on the main carrier.”
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The firm’s mechanical crushers use the excavator’s hydraulics to crush concrete in the demolition of bridge decks, buildings, floors, foundations, pillars, and roads. They can be equipped with four-way rotatable blades for cutting rebar, and with hydraulic shears for cutting steel beams and metal structures. “The shears have been improved recently with a new valve to reduce the cycle time and speed up the cutting process,” Min says.
Planing a Road
A contractor repaving a road may use a planing machine to shave off the top inch to 6 inches of asphalt or concrete, creating a scored surface on which to lay down the new pavement. Coneqtec Universal in Wichita, KS, makes planers that attach to a skid-steer and connect to its hydraulics. They cost $12,000 to $25,000.
To reduce power loss from the milling assembly’s drum and pics (the spikes that come in contact with the asphalt or concrete) passing through already planed material, the Universal planer has a patented open drum design that discourages material from becoming trapped between the drum and the pics.
“Instead of a round drum, we have the pics mounted on plates so the spoil from the milling doesn’t get caught on the head and get milled over and over to make a fine dust,” explains Kelly Guthrie, marketing coordinator. “Our planer leaves a thicker aggregate with less dust and less work for the skid-steer. Also, our pics will last longer because they’re doing less work, not remilling over and over.”
Guthrie says the pics should last 20 hours to 30 hours in concrete, or 50 hours to 120 hours in asphalt, depending on the nature of the road surface, the depth of the cut, and whether the pics are clean and free to rotate. If so, they self-sharpen. If not, they grind down to stubs and must be replaced.
Universal planers range in width from 12 inches to 48 inches, and in pic complement from 16 to 106. When the pics must be removed for servicing, a “male” shank on each pic fits into a “female” holder similar to a socket wrench.
Author's Bio: George Leposky is a science and technology writer based in Miami, FL.