At an industrial zoned site in Forest Hill, Maryland, USA, Celtic Demolition operates a recycling yard that converts construction debris to usable material at the same time it helps maintain air quality. The latter environmental feature is a consequence of Celtic?s switch to a piece of machinery powered by a Tier IV engine.
Celtic?s huge, rumbling mechanical crusher that spews out shattered concrete in sorted piles of aggregate is a Powerscreen XR400S, a latest generation mobile recycling crusher weighing almost 45.3 tonnes. The crusher was one of the first Powerscreen units sold in the US with a Scania engine which meets Tier IV standards as well as European Union Stage IV standards. Previous Powerscreen models used Caterpillar powerplants.
Scania is a Swedish manufacturer that turns out some 80,000 industrial, truck, bus, and marine engines every year. Scania-powered trucks and buses are commonplace in Europe and other parts of the world but are relatively rare in the United States.
?I was familiar with Scania in Europe,? said Ross Tumulty, co-owner and president of Celtic Demolition. Tumulty is a native Irishman who came to the United States in the early 1980s. ?You see a lot of Scania trucks and equipment there. From everything I hear, the engines are very good. They are very successful in Europe.?
CELTIC ROOTS
Tumulty was a paving contractor in Ireland, but when he arrived in New York, he switched to construction.
He worked as a labourer for a couple of years. Shortly after, the general contractor transferred him to the Washington, DC area. After opening an office there, Tumulty noticed that the contractor was subbing out its demolition work. He decided in 1985 to try to capture part of the business and started Celtic Demolition.
Two years later, he met in the States another Irishman, David Kavanagh, a native of Dublin, who joined Celtic and is a co-owner today. The firm is headquartered now in Alexandria, Virginia, and has grown from demolishing and extracting materials from the inside of buildings to taking down entire buildings and bridges. A used John Deere 792 excavator was the young company?s first piece of equipment.
?Now we have a bunch of big toys to take down big buildings and bridges,? Tumulty said.
Probably the biggest ? and certainly the tallest ? piece of Celtic equipment is a 117,934kg Hitachi 850 with a high reach boom that fractures and snatches apart structural elements 13 stories above the ground. Celtic thus introduced to the DC area multi-storey boom demolition, as opposed to the traditional method of demolishing tall structures using a wrecking ball swinging from a crane.
The demolition company oddly enough also performs historic preservation work, wherein historic facades are preserved or carefully taken down before the rest of a building is levelled. Celtic performs excavation work as well, but only in conjunction with demolition. Often a cleared site needs sub-basement or footing work completed before a new building can rise and Celtic segues into that phase of new construction as part of an all-in package of site services. Stand alone excavation projects are not solicited.
The other mainstay business activity for Celtic, whose annual business volume exceeds $8 million, is bridge demolition. One of the company?s highest-profile bridge projects was the dropping of a half-mile of the Woodrow Wilson Bridge connecting Virginia and Maryland.
The steel usually ends up at Super Salvage, a DC area yard that takes most of the steel, aluminium and copper refuse that Celtic collects in its operations.
Celtic recycles an estimated 90 per cent of the debris from all its demolitions, according to Tumulty, and that?s where the Powerscreen crusher comes into play. While Tumulty does not know how many tonnes of concrete his recycling equipment processes each year, virtually all the chunks of demolished buildings are turned into usable aggregate for backfilling and similar functions. The recycling occurs either on site at a general contractor?s request, or in Celtic?s Forest Hill yard.
BIGGER, STRONGER
The company?s XR400S replaced a smaller 31,751kg crusher of another brand. That the new unit is larger than the one it replaced is in itself a good thing, Tumulty said. ?Bigger is better. We always go by that in demolition. Bigger is better.?
Sheer weight usually translates into heavier, stronger components. In a crusher, that means it can more quickly gulp down chunks of concrete.
{{image2-a:r-w:250}}?It just has a great appetite for concrete,? Tumulty said of the XR400S. ?It is very fast at what it does, twice as fast as the previous unit, and that?s important. You don?t want to be spoon-feeding these things.?
Speed can pose some hazards for crushers, however. Sometimes bound into larger chunks of concrete are rebar and I-beam fragments, the steel reinforcement structural elements that no crusher can crush. The ?R? in XR400S addresses ?this problem.
The ?R? stands for ?release? and alludes to a hydraulic feature that Powerscreen pioneered. When an uncrushable element is encountered by the jaws of the crusher, the jaws automatically and hydraulically spring apart and drop the offending object and convey it out of harm?s way. Then the machine operator hits a reset button and the crusher recalibrates itself and resumes its work.
?What happened in the past,? explained Mark Keenan, of Powerscreen Mid-Atlantic Inc, which sold the XR400S to Celtic to complement its Powerscreen Warrior screen, ?was that if the operator didn?t see the steel and extract it, it would cause major damage to the jaw of the machine. All of a sudden, all the inertia of the jaw?s closing would fire back to the bearings and shaft and almost break it. Considering how much violence is involved in the fracturing process, such a sequence is easy to imagine.?
The Powerscreen unit also features a direct drive instead of the hydraulic drive found in most competitors? equipment. Consequently, about 95 per cent of the power generated by the Scania engine is directed toward the crushing process, compared to 75 per cent in machines using the less efficient hydraulic drive.
Coincidentally, Keenan also is from ?Ireland, the headquarters of Powerscreen, where he began working for the company. The Powerscreen Mid-Atlantic Inc dealership opened in Kernersville, North Carolina in 1996 and Keenan has worked there since 2002. He has helped the business grow in North Carolina, Virginia, South Carolina, and West Virginia. Mid-Atlantic also ?carries auxiliary equipment, including TeleStack conveyor systems and Kiverco recycling systems.
Mid-Atlantic operates a rental/leasing yard in Ashland, Virginia, where area contractors can get hold of crushers, screens, and conveyors for on-site recycling work.
?As opposed to digging up the rock and trucking it away, then paying quarries for aggregate to use on-site, contractors rent our machines, pull out the rock, crush it, screen it and make the correct size gravel they need right on-site,? Keenan said.
PORTABLE, MOBILE
The portability and mobility of crushers makes such on-site applications possible. Keenan notes that Powerscreen made the first tracked crusher in the late 1990s ?and the market exploded. All of a sudden contractors were all about it. With the price of aggregate going up, more and more contractors don?t want to spend so much money with the quarries?.
In these ways, Celtic Demolition uses its Powerscreen crusher, either on-site or in its recycling yard, whichever best suits a project and general contractor.
Tumulty said the US recession?s impact on construction has been felt in the demolition industry. ?Usually one (construction) affects the other (demolition),? he observed. ?Project owners usually don?t tear down something until they are ready to build right behind it, and finance it all in one package.?
After private sector work dried up for his 50 employees, Tumulty and Kavanagh targeted government entities for demolition projects ? including bridges and other infrastructure in the District, northern Virginia and ?southern Maryland.
Travelling to other areas in the Atlantic region is not something the Celtic owners will be doing in these tough economic times. The company once took on a project near Philadelphia, but Tumulty said that they concluded it wasn?t the best business model for Celtic. ?We have the contacts here. We have the dump sites here.?
And now the company has in its recycling yard a crusher with a voracious appetite for concrete debris.
In Australia, Powerscreen products are distributed by the Lincom Group.
Source: Powerscreen Mid-Atlantic