Successful grading and excavating contractors are, if anything, resourceful when it comes to meeting a challenge. The worst recession in memory for most of them has highlighted the value of making the most of every available resource. Those resources include materials once considered a costly disposal problem—such materials as stumps, logs, and treetops left from land-clearing operations and chunks of concrete, asphalt, and rocks littering a demolition site in preparation for redevelopment activities.
That’s where onsite recycling can pay off. Self-propelled, track-mounted grinders can maneuver easily up and down grades and in and out of muddy areas to process greenwaste into hog fuel and mulch. Meanwhile, tracks enable engine-driven compact crushers to move around a job site as they convert concrete and asphalt rubble, rock, bricks, and blocks into material for use on the project as a valuable aggregate for slabs, sidewalks, parking lots, streets, or highways.
D.J. Cavaliere co-owns Cor Equipment Sales in Stamford, CT. A dealer for Rubble Master Compact Recyclers, his company serves contractors in a seven-state region extending from Pennsylvania to New Hampshire. They are split fairly evenly between two types: those who provide crusher services for customers having trouble finding a place to dispose of their concrete and asphalt debris; and contractors doing site development and grading and excavating work who want to recycle their own concrete and asphalt rubble into usable construction materials. “These contractors don’t want to pay to dump this waste and then pay again to buy and truck in new aggregate,” he says. “More and more contractors want to process their own materials, which may be worth from about $10 to $20 a ton.
Most of his sales start out as rentals, he notes. Although sales have dropped during this recession, Cavaliere reports, rentals have increased. “These days, contractors are looking for different avenues to increase efficiency in their business,” he says.
For land-clearing operations, track-mounted grinders offer several advantages over towed wheel grinders, notes Tim Wenger, president and sales manager for CW Mill Equipment Co. Inc., which makes the HogZilla line of tub and horizontal grinders. “You don’t have to clear a road to move a track grinder around a job site,” he says. “Also, because they are remotely controlled, they’re extremely versatile. A loader or excavator operator can walk a track grinder around with them to make grinding a one-man operation. That same operator can bring the machine to the woodwaste and load the material into it. You don’t need a separate operator and machine to push material to the grinder and another operator and a different machine to feed it.”
Machine Differences
Manufacturers offer two types of crushers for reducing rock, concrete, asphalt, brick, and the like into recyclable construction materials. An impact crusher features steel blow bars mounted on a flywheel rotor inside a crushing chamber. As this large metal mass rotates, the blow bars, spinning at a high rate, break the material on impact and shatter the debris. This material must then pass between the spinning rotor and the impact wall at a predetermined “gap.” Any material too large to pass through this space is impacted with the rotor until small enough to do so. This material then drops to a moving belt that conveys the crushed materials out of the machine.
A jaw crusher, used primarily with virgin rock, produces aggregate and rock fill by squeezing rock between a fixed plate or jaw and a moveable plate, the other jaw. When viewed from the side, the two plates are mounted to form a V-shape so that the opening between them is wider at the top than at the bottom, similar to a funnel. Rock, larger than the bottom opening, enters the crusher from the top and becomes lodged between the two plates. The moveable jaw plate then exerts force on the rock, compressing it against the fixed plate. The size of the final crushed product is determined by the size of the gap between the bottoms of the two plates.
One of the latest advances in the design of compact mobile crusher is a 16-ton, remote-controlled track unit, which can be transported on a trailer pulled by a dump truck and which can operate either as jaw or an impact crusher by unbolting one type of crushing mechanism and bolting on the other. “That conversion takes less than an hour,” says Bob Rossi. He’s vice-president of R.R. Equipment Co., which designed and produces the machine at its plant in Lancaster, SC.
Called the Rebel Crusher, it was introduced two years ago. The patent-pending machine features a 20-inch-by-36-inch feed opening and can crush rock and recycle debris down to as small as three-quarters-of-an-inch, Rossi reports. It comes standard with a screen to regulate size of the finished product. Options include a self-cleaning permanent magnet, a two-deck sizing screen, and three folding-screen stockpile conveyors.
The machine is designed specifically for small to medium contractors, Rossi notes. “We build this crusher for contractors who need a mobile machine occasionally to work in confined areas, who don’t have a huge amount of material to process on the site, and who don’t want to pay the price of a larger crusher,” he says.
Komplet Italia S.r.l. makes two even smaller mobile-track jaw crushers for crushing glass, porcelain, marble, granite, bricks, blocks, asphalt, and reinforced concrete. The remote-controlled Lemtrack 48-25, which weighs 7,200 pounds, includes a feeding system.
“You can tow it behind a pickup truck on a standard 5-ton equipment and feed it with a mini-excavator or skid-steer loader,” says Nick Baker, president of Compact Concrete Crushers, the North American distributor for Komplet. “This machine can produce a product ranging in size from three-eighths of an inch to three-and-one-eighths inches and typically process about 15 tons per hour in normal operation.”
It’s designed for contractors who usually do smaller projects, like sidewalks, driveways, patios, and swimming pool enclosures, he reports.
Normal production for the 12.5-ton Lemtrack 60-40 model, which has a feed opening of 20 inches by 24 inches, is around 60 tons per hour of three-quarter-inch to three-and-seven-eighths-inch product, Baker reports. Options for the remote-controlled mobile crusher include a rebar separator and a dust-suppression system.
“This machine can handle many of the same jobs as a large, more expensive crusher,” he says. “Of course, this smaller machine will take more time to complete the job, but it has a lower price and much lower operating costs.”
Two types of grinders are available for processing woodwaste. Both use a series of hammers or cutting tools mounted on a shaft, which rotates at high speeds, to reduce logs, stumps, and brush to the desired size. The size of the finished material is controlled by the size of the openings in a screen. A tub grinder features a rotating tub with an open top. Once fed into the tub, the woodwaste passes into the mill. A horizontal grinder, on the other hand, features a horizontal conveyor, which feeds the material through a rectangular opening into the mill. Typically, a self-propelled track grinder costs about $75,000 more than a towable wheel model with similar production capabilities, Wenger reports.
Owning and operating a grinder for processing woodwaste left from land-clearing operations isn’t for everyone, including smaller contractors, says Tee Ray, president of Bob Ray Co. in Louisville, KY. The list of services offered by the company, which operates in its home state as well as Indiana, Ohio, and Tennessee, includes clearing land and grinding woodwaste into hog fuel and landscape mulch.
The company owns a Bandit 3680T and two 4680T Beast Recycler horizontal track grinders.
“There’s a night-and-day difference between buying a grinder, which can cost upwards of $750,000, and buying a dozer or an excavator,” he says. “You can’t just purchase a grinder and start grinding. It takes a tremendous amount of training in preparing material for grinding and feeding it into the machine properly if you want to keep production up. It also requires a lot of maintenance. In a normal workday, we’ll grind for six hours and spend the last two hours on maintenance, such as greasing, checking fluid levels and air filters, ensuring that the teeth, hammers, and cutter bars in the cutter mill are in good condition and everything is within specifications. Sure, you can spend seven-and-a-half hours grinding and half an hour on maintenance. But, the next day, your production will be down.”
Recycling Wood and Asphalt
In Bellingham, WA, Barker’s Woodchipping Service Inc. has been clearing forestland for residential and agricultural development and road construction projects since the early 1990s. The company grinds logs, treetops, and stumps into hog fuel to power cogeneration plants and, occasionally, into mulch for controlling erosion on construction sites. Last year, the clearing and grinding projects ranged in size from a 1-acre parcel for a new house to an 80-acre site for a raspberry farm.
At one time, the company used tub grinders mounted on wheels to covert woodwaste into a marketable product. However, since 2008, a track-mounted horizontal grinder, the company’s first horizontal model, has been doing the work.
“We get better production from the horizontal-style grinder than the older tub grinders we once used, although the technology of the newer tub grinders has improved quite a bit since we had ours,” says Herb Barker, president of the company.
The steel tracks add to the grinder’s productivity, he notes. “It seems like the ground is always wet and muddy here,” Barker says. “But that’s not a problem with the tracks. They’re so much nicer than trying to drag a rubber-tired grinder out of the mud. Sometimes, it would take us all day just to pull one of those machines into a job site. With the tracks, mud and steeper ground aren’t a problem. We can move the grinder wherever and whenever we need to and can work all year long.”
Barker bought his current horizontal grinder, a DiamondZ DZH4000TK, in 2008. Usually, he loads the remote-controlled machine with his Volvo 210 log loader. Equipped with a rotating grapple, it makes feeding the grinder easier than using his Hitachi 300 excavator, which is used in his grinding operations mostly for pulling out tree stumps, and gathering brush.
To produce hog fuel, which he sells to a pulp-and-paper manufacturer for use in generating electricity and steam, he grinds the wood to about a 6-inch-minus size. He makes the same size material for mulch. In this case, the processed woodwaste is spread about 6 inches thick to cover bare ground on newly constructed wetland mitigation sites.
The bane of crushers and grinders is steel and other hard metals hidden within the rubble and debris. Ranging from rebar to hand tools, these hard materials can cause a major maintenance headache. Although his compact impact crusher can handle some rebar, depending on the final size of the processed material, custom crushing contractor Paul White says the most important job of his crusher operator is to make sure no steel gets into the crushing chamber. “Steel going through a crusher is not a pretty picture,” he says. “If the piece is big enough, it can take a chunk out of the impactor.”
White, who owns Bulldog Crushing in Indianapolis, IN, uses his mobile compact crusher, a Western Retek Supertrak 1310i model, to recycle asphalt, concrete, rock, and bricks for construction contractors and other customers. Depending on their needs, he reduces this rubble to sizes ranging from about 3 inches down to dust.
In the case of asphalt, for example, he usually crushes it to a one-half to three-quarter-inch material. “Depending on where and how it will be used, this material may be blended at the rate of 15% to 28% to produce new asphalt,” he reports.
Customers who don’t reuse the crushed material as a sub-base for roads, sell it to other contractors who incorporate it in their projects, he says.
Tubs on Tracks
At one time, Joey Adams and his brother Lance of Waco, GA, were grading contractors. But in 2002 they downsized, forming Adams Clearing to focus strictly on clearing land, mostly for road construction and commercial site development projects. Their first grinder, which they bought two years later, was a HogZilla wheel model. In 2007, they replaced it with a HogZilla HTC-1462T self-propelled track-drive tub grinder. A year after that, they added a second machine of that same model.
“We really like the track grinders,” Joey Adams says. “They’re so much easier to maneuver around the job site, whether the ground is wet or dry. When the ground was wet, we could hardly get the wheel grinder around the job site using a 10-ton, 6-by-6 military truck to pull it. Also, with the tracks, we can just walk the grinders from one pile of stumps and tree debris to another.”
The brothers use the machines with various size screens to grind tree debris into 1-inch to 7-inch material that they sell to paper mills for powering boilers or electrical generators.
Among the features that Adams likes about the grinders is the torque converter drive for the hammer mill. “It’s virtually trouble-free and requires no maintenance,” he says. “Also, the machine is built simply, without a lot of electronic controls, so it’s easy for us to work on it. Because it uses some of the same parts in other types of equipment, parts are available from a number of different suppliers.”
Even with the downturn in the economy, the Adamses have continued to find regular work for the two grinders. “The only reason we’ve been able to keep busy is our really good customer base,” Adams says.
David Littlefield, Kirbyville, TX, is another grinder owner who appreciates the value of recycling green woodwaste. In 1983, he started a land-clearing company, Littlefield Dozer, removing stumps, logs, and other slash from areas being prepared for development. These early land-clearing projects ranged in size from home sites and farm fields to shopping centers. “Back then, we either piled up all the wood debris and burned it or spent a lot of time hauling it to a landfill,” Littlefield says. “I thought there had to be a better way to than just wasting this stuff.”
That’s when he began an extensive investigation of grinders, attending equipment shows, studying product brochures, and talking with manufacturers and owners of grinders. He settled on a DiamondZ 1036 tub grinder, with a 10-foot diameter tub and mounted on wheels, and started grinding tree trunks, branches, and stumps to produce hog fuel to run boilers at paper mills. That machine is now used as a backup to his two newest grinders—both DiamondZ model DZH4000TK track-mounted horizontal grinders—which he and his son operate. Littlefield bought one of them in 2008 and the other last year. Each is stationed at a different paper mill.
Using Caterpillar 315 excavators to feed the machines, the grinders run about 10 hours a day, he reports, during which they produce about 2,500 yards of fuel. The tracks make moving the remote-controlled horizontal grinders, each of which weighs more than 90,000 pounds, easier than using a truck to pull a wheel grinder, he says.
“From time to time, we have to move the grinders to clean out from underneath them or to grind at a different location at the plant,” Littlefield says. “I don’t to bring in a big truck to do that. Usually, we run the grinders on concrete. But, they can also go over soft or muddy ground, where I may need to throw down some mats to keep the heavy machines from sinking.”
He continues to use his original wheel-mounted tub grinder. “If we get caught up on grinding at one mill, we’ll take that machine to help out at the other mill.”
Cost-effective production capability is important for Tee Ray, president of Bob Ray Company, Louisville, Ky., when buying a particular make or model of grinder. However, he also judges the value of a machine based on three other key factors.Product support—“No piece of equipment is any good if you don’t get good backup from the manufacturer,” he says. His criteria for measuring good support for a grinder is the ability of the manufacturer to deliver parts for the machine within 24 hours and, if necessary, to get a factory service technician on site within 24 to 48 hours.
Dependability—Before buying, Ray wants to have a firm idea of how many hours of operation he can expect from the machine in a day, compared with required service time. He does that by getting recommendations from others in the grinding business
Adaptability—Ray wants a grinder that can also be used for chipping. “Depending on the manufacturer, some machines offer numerous screen, hammer, and knife options for using grinders to chip wood or even for grinding asphalt shingles into material for making new asphalt.
Three More Key Factors
Favorable power-to-weight ratio—Barker’s Woodchipping Service Inc. in Bellingham, WA, has a self-propelled grinder that weighs about 82,000 pounds, reports owner Herb Barker. “It’s small enough that we can haul it ourselves using our lowboy trailer,” he says. “Yet, it has great power and the ability to produce.”
Minimal maintenance needs—He changes hammer tips as they wear out. Typically, four or five wear out every couple days. Barker replaces them all at once, a job that requires about five minutes each, he notes. The hammermill grinds the wood against a cutter plate. On his current model, one side of this plate lasted a year before he had to reverse it to use the unworn side. That task took about two hours to complete.
High conveyor belt—Unlike some grinder operators who discharge the grinder’s output onto the ground, Barker likes to load it directly into his chip van. “The conveyor belts on some grinders aren’t high enough to do that,” he says. “If the wood is right next to the grinder, we can grind the wood and convey it to a 120-yard chip van in about 20 minutes.”
Simple construction—Among the features that Joey Adams of Adams Clearing in Waco, GA, likes about his grinders is the torque-converter drive for the hammermill. “It’s virtually trouble-free and requires no maintenance,” he says. “Also, the machine is built simply, without a lot of electronic controls, so it’s easy for us to work on it. Because it uses some of the same parts in other types of equipment, parts are available from a number of different suppliers.”
Sturdy construction—“I want a real beefy machine,” says grinder owner, David Littlefield, Littlefield Dozer, Kirbyville, TX, “That means one that is well put together with thick metal and parts, bolts, and bearings that are built tougher than they should be. A grinder takes a real beating and that type of construction saves you from down time. I’d rather spend the extra money for a heavy-built machine than waste it on a lighter machine that breaks down and requires a lot of repairs.”
Ease of servicing is also a must for him. That includes screens that he can reach and replace without too much difficulty.
Processing efficiency—The efficiency of crushers in reducing rubble to the desired finished size can vary among different brands due to differences in design and technology, notes A.J. Osborne, Villager Construction, Fairport, N.Y. For example, one machine may produce 200 tons of finished material an hour. However, in doing so, 50% of the original crushed material is returned to the impact chamber for additional crushing to achieve the final size. As a result, the machine actually processes 300 tons per hour. “I don’t get paid for the amount of material I crush per hour,” he says. “I make money only how much finished product actually ends up on the ground. I’d much rather have a more efficient crusher that crushes 300 tons per hour to produce 285 tons of output That increased production efficiency is easier on the machine and much more profitable.”
Component quality—Demonstrating various crushers opened Osborne’s eyes to how differences in the quality of components can also affect profits. After one week of use, the cost to replace the worn mild steel blow bars on three different makes of crushers was $7,000. By contrast, the more expensive, but much more durable ceramic-coated blow bars, which cost up to about $9,000 per set, lasted a month. The cost of the blow bars on Village Construction’s machine range from $2,000 per set for the mild steel and up to $4,000 per set for the ceramic-coated bars, much less than price of bars for the other machines Osborne tried.
Shopping Advice
The efficiency of crushers in reducing rubble to the desired finished size can vary among different brands due to differences in design and technology, notes A.J. Osborne, Villager Construction, Fairport, NY. For example, one machine may claim 300 tons per hour production. However, to achieve that, 30% to 50% of the original crushed material is returned to the impact chamber for additional crushing to achieve the final size. As a result, the machine actually processes 150 to 200 tons of finished product per hour “I don’t get paid for the amount of material I crush per hour,” he says. “I only make money on how much finished product actually ends up on the ground. I’d much rather have a more efficient crusher that crushes 250 tons per hour to produce 225 tons of output. That increased production efficiency is easier on the machine and much more profitable.”
In June 2009, when many grading and excavating contractors were hunkering down and selling equipment and trimming payrolls to weather tough economics winds, Villager Construction of Fairport, NY, took a different direction. The excavating and paving company, which employs about 250 field people, spent several hundred thousand dollars to buy its first machine for crushing rock, concrete, and asphalt—a track-mounted impact crusher.The goal of the machinery investment is to increase profits by expanding the company’s lie of services and by adopting greener, more sustainable construction practices, reports A.J. Osborne, the company’s Aggregate Recycling Division manager. This new venture traces back to 2008 when Villager Construction was reconstructing a mile-long section of Route 15A, a suburban highway near Rochester, NY. The work included tearing out the existing asphalt and concrete pavement and preparing a new sub-base for the highway, which varied in width from five to nine lanes.“At the time, fuel prices were going through the roof and the costs of transporting the concrete and asphalt rubble to a waste site and hauling in new base material were getting out of control,” Osborne recalls. “We needed to do something to manage our profits on the project.”
Reusing the asphalt and concrete waste onsite by crushing and then blending it with aggregate to produce new sub-base material offered a way to do just that. “We saw the handwriting on the wall,” he says. “Not only would recycling be economically viable for us, but it was also environmentally friendly. The New York State Department of Transportation agreed to this green approach.”
So, the company hired a subcontractor to do the crushing work on its first recycling project. However, because of conflicts in scheduling this work, Osborne and other project leaders decided to look into doing the job themselves. And so began a lengthy process of researching and demonstrating different makes and sizes of crushers.
Award-Winning Work
The first machine they tried was a large, non-mobile impact crusher typically used in rock quarries. “It offered high production rates, but the costs in time and money to break it down, move it to a site, and set it up again were staggering,” he says. “We would have to be operating on a much larger scale than the typical onsite recycling project to justify its cost.”
After investigating several different brands of smaller, self-propelled impact crushers, Osborne tried out a Rubble Master RM100 track-mounted machine. Originally, he estimated the machine would produce about 100 to 150 tons per hour of three-quarter-inch minus recycled asphalt material. While much lower than the 300-ton-per-hour production of the first quarry-sized crusher, Osborne figured that eliminating the mobilization expenses of that crusher would make up for the lower production of the smaller machine. However, when used with a large secondary dual-deck screener unit, the RM100 actually produced 380 tons of recycled asphalt per hour.
“That’s when we realized that the machine could be used for more than a one- or two-day job on a small project,” Osborne says. “It was a full-service machine.”
After a two-day demo, Villager Construction purchased the unit to finish the highway project. The work to process and reuse existing pavement along with salvaging and reusing the original gravel sub-base and stone curbs earned the company the Region 4 2008 Contractor Environmental Quality Recognition Award from the NYSDOT.
All of the existing stone curb was reused and 100% of the sub-base and select granular fill used on the project was recycled material. Processing the asphalt and gravel was done onsite, eliminating the need to mine 19,100 tons of sub-base material and 8,700 tons of select granular fill material. At the same time, about 1,200 truckloads or 27,800 tons of material was reused rather than disposed of in a landfill or spoiled offsite. By reducing the number of trucks and distances traveled for the project, onsite recycling also cut fuel costs, lowered diesel emissions, and eased congestion on surrounding highways.
In most cases Osborne uses the crusher to produce material larger than three-quarters of an inch. Rather than bringing in a secondary screener that conveys oversize material to a stockpile for recrushing later, he takes advantage of the RM100s onboard screener. With this closed system, any oversize material is sent back to the impact chamber automatically for efficient operation.
Recycling Economics
Using a crusher to convert concrete and asphalt debris into a sub-base material eliminates the cost of buying it. However, that alone, can be a relatively small advantage, notes Osborne. Currently, for example, he charges about $5.50 per ton to produce sub-base material with the machine. That’s not much less than the $5.75 a ton local contractors pay for virgin limestone aggregate.
The main economic advantage of this type of recycling for contractors, he notes, is that it solves the problems of disposing of the debris and continually increasing restrictions on the type of material that landfills will accept. Hauling debris to a landfill and paying the tipping fees can total about $10 to $15 per ton, Osborne says. Then, there’s the cost of bringing in sub-base materials. In the case of dumping the waste at a fill site, most contractors have to provide a dozer and operator to stockpile or spread it out. Also, onsite recycling eliminates the environmental costs associated with engine exhaust emission from the trucks and other machines involved with these activities, including mining of the raw aggregate.
“In our area everyone uses the same type of equipment and buys aggregate from the same small pool of suppliers,” Osborne says. “So, 90% of the time, the bid goes to the guy closest to the dump site, the one with the lowest trucking costs. Often, we can recycle concrete and asphalt debris on a customer’s site cheaper than they can haul and dispose of it while providing the customer a product they can use on their project.”
In some cases, project owners can also profit from government incentives designed to encourage recycling. “By using materials from crushed up concrete and asphalt in their projects, many of our customers, including municipalities, have qualified for additional federal funding or property tax credits,” Osborne adds.
Business Expansion
Since Village Construction bought its track-mounted crusher, the company has established a new recycling division. It has opened a yard in Rochester to take debris from other contracts to supply sub-base material for its own projects and other vendors. On one large project, the crusher provided more than 20,000 tons of recycled aggregate to meet a New York DOT specification for sub-base material. It consisted of a blend of 70% to 80% 2-inch-minus crushed asphalt with the rest being 2-inch-minus recycled concrete. Osborne reports it tested higher in density than virgin 2-inch crusher-run limestone.
However, Osborne has discovered other markets for a compact mobile crusher. One of them is that of smaller gravel pits that don’t have the budget to buy a large crusher. “In the past, only quarries with that type of machine could supply sub-base material,” he says. “The smaller gravel pits would screen material and sell a round or cleaned product that wasn’t suitable for a sub-base. However, with our machine, we can process their gravel that’s not suitable as a sub-base into materials that meet DOT specifications as a road sub-base. In some cases, we’ve doubled the annual production of small gravel pits.”
Another market for the company is that of asphalt producers. The mobile crusher is used to process asphalt debris into material that meets New York DOT specifications, Osborne notes. “These specifications have been rewritten to allow the use of recycled asphalt material,” he says. “This consumes fewer resources, reduces emissions and helps keep tars and oils in asphalt debris out of landfills.
As Osborne points out, all this is just the beginning for Villager Construction’s recycling division. “Our intention,” he says, “is to build up our recycling business on the East Coast and have a dozen or so crushers on the job within the next three to five years.
