27 February 2008
Demolition is a growing part of the construction industry around the world, driven by the need to modernise and regenerate communities. It is a specialised discipline – the task of demolishing buildings can obviously be dangerous – and as a result often requires specialised equipment and techniques.
One of the most striking types of machine used in the industry is the long–reach demolition excavator. These were first developed in the 1980s and 1990s, as a more accurate and safer alternative to the traditional technique of using a crawler crane to swing a wrecking ball into the unfortunate structure to be demolished.
High reach excavators have the advantage that they can carry a variety of tools – usually either a hydraulic breaker, or specialised crushers and shears for cutting concrete, masonry or steel. Mounted on the end of a long boom, these tools can be positioned with great accuracy by a skilled operator, and so allow buildings to be demolished in a safer and more selective manner.
These machines have become more and more popular over the years, and bigger is certainly better. According to iC's sister magazine, Demolition 'Recycling International (D&Ri), Rusch, an engineering company based in Amsterdam, The Netherlands is currently modifying a 68 tonne Cat 5110 B mining shovel to give it an enormous 90 m vertical reach.
This monstrous machine will be able to use a 6 tonne attachment at its full vertical reach, and will be able to handle a 12 tonne tool at 80 m, making it capable of demolishing tower blocks around 30 storeys high.
One of the major changes in the high reach sector in the last two years has been the use of telescopic booms to achieve these huge heights. Similar in appearance to mobile crane telescopic booms, these have pushed the envelope of vertical reach well above the 65 m mark, which was about the limit achieved using multi–piece articulating (but non–telescopic) booms.
Prior to this advance, the world record for a high reach demolition machine was held by Kobelco, which modified an SK3500D crawler crane chassis in 2005 to give it a 65 m reach.
Of course machines like this are an extreme example of the high reach market and are sold in very small numbers. The SK3500D had a list price of JPY 1 billion (US$ 8.7 million), and there are relatively few demolition projects that suit such big machines. Although their high reaches suggest demolition of urban tower blocks, such sites can be too cramped for such big machines. Industrial demolition projects – power stations and so on – or more sparse urban areas where there is enough room for them to operate safely can be more suitable.
Smaller but still 'high reach' machines have become very popular over the last ten years, particularly in the European demolition industry. The market leader for high reach booms over 40 m in Europe is undoubtedly Ipswich, UK, based Kocurek.
It seems to be a boom time for high reach machines at the moment. Ron Callan, product manager at Kocurek, told iC, “We have the best forward order book we have ever had going into this year.”
But it is not all about height. Kocurek product manager Bradley Higgs believes that productivity is of equal importance. He told iC, “For some, height is not the driver. Ultra high reach may grab the headlines, but there is another requirement out in the marketplace that is more to do with productivity. Customers want to use bigger tools at height. Up until now, tool weights on the big high reach machines were rarely more than 2.5 tonnes. Now people are looking for 4.5 to 6 tonnes at 30 m and beyond. Some of our recent machines have this kind of capability.”
It is often said that Europe is currently the true home for high reach excavators, and certainly that is true for the past, but things might be changing.
Jewell is arguably the North American equivalent of Kocurek, and it reports a considerable growth in demand for its custom-designed demolition rigs, with more that two dozen being sold in 2006. National sales and marketing manager Mark Ramun said, “The largest have been turnkey ultra-high rigs reaching over 56 m, capable of carrying a 2.5 tonne attachment. We have seen a spike in interest for more purpose built machines for the demolition and recycling industries and anticipate an even higher demand for these types of machines in the future.”
High reach is a relative term, and while the massive machines in Europe and the US may be the most noticeable examples of the art, the concept has been applied a little differently in Japan.
Japan's cramped cities are often not suitable for relatively large high reach machines, and so the traditional demolition techniques have tended to be top–down methods. These involve lifting mini excavators to the top of the building and using them to take it down a floor at a time with hammers or crushers. Debris is cleared through a 'well' of holes through the centre of all the floors – waste is simply pushed in and drops to ground level.
But high reach demolition has come to Japan, albeit on a smaller scale than in Europe and the US. The concept has been applied to housing demolition, with 3.5 tonne class mini excavators being modified with a long reach three–piece boom that can offer pin heights around 8 m. Caterpillar, Hitachi and Kobelco all offer such machines in Japan.
The range of attachments used in demolition can be a bewildering one. Again it is an area that has grown and diversified a lot in the last 10 years or so, with more attachments being developed for specific applications, and ranges being extended. Hydraulic breakers are still a mainstay of the industry, but even the modern generation of silenced units can be relatively noisy.
At the same time, the popularity of various types of pulverisers, cutters, shears and grapples is on the rise, especially as the design of such units improves. A common feature today is for cutting-type tools to be fitted with changeable jaws, or multi-purpose jaws that allow them to cut both steel and concrete.
Once a structure has been demolished, many countries now require that the 'waste' is recycled rather than dumped. This is either done by specific laws banning the landfilling of material, or taxes on landfill space which make it more economic to recycle than to discard.
In order for recycling to be effective, waste has to be sorted out into different types. A lot of this is done in the stripping out phase of demolition, before the structure is dismantled, but this can only go so far, and the industry has developed a range of techniques for separating and re-using structural materials like concrete, masonry and steel.
Problem materials include composites like reinforced concrete, and here excavator-mounted crushers and pulverisers are often used to break the concrete away from the rebar.
Once separated, materials like concrete, bricks and blocks can be crushed and sized for use as aggregates. Although there are strong similarities between the crushing and screening equipment used for virgin aggregates production and recycling demolition waste, there are a few key differences.
First, equipment used for recycling has to be mobile. Aggregates tend to be crushed on site or nearby, so the flexibility that mobile machines brings is essential.
Second, the crushers and screens used in recycling are often at the smaller end of the scale. They have to be easy to transport on and off site, and not take up too much space while they are working. Another reason that recycling crushers tend to be smaller is that they do not usually have to deal with the high volumes of materials that quarries do.
Like the demolition sector in general, the market for recycling equipment has come a long way in the last 10 years or so, driven in part by the increased impetus to recycle demolition waste from laws and taxes. The growth in the smaller end of the mobile crushing 'screening sector has elevated it from something of a niche market, served by relatively small regional players, to a genuine multi–national business.
This is witnessed by the number of significant acquisitions in the sector over the last year. April saw Sandvik acquire the remaining part of Fintec it did not already own, as well Extec, one of the leading lights of the sector.
Speaking on the rationale behind the acquisition, Sandvik Mining 'Construction president, Lars Josefsson said, “We have been active in mobile crushers since 2001 with the acquisition of Svedala, but as a minor player. We could have expanded organically, but we had the joint ownership of Fintec and had the opportunity to acquire other companies. We will extend our offering with the Fintec and Extec acquisitions. We see this market as being substantial and worth going after.”
Another interesting development just over a year ago was the acquisition of 80% of German crusher manufacturer Kleemann by the Wirtgen Group. The company has been incorporated into the Wirtgen Group as a new business segment called Wirtgen Mineral Technologies, with Kleemann's managing director, Dr Gerhard Schumacher continuing to lead it.
Every aspect of the demolition and recycling industry has changed over the last 10 years with bigger, more specialised and more sophisticated machinery being developed at an incredible rate. More to the point, this is still very much an emerging industry. The forces that drive it – regeneration and sustainability – are becoming more and more important in the world, so the next ten years in the industry promise to be at least as exciting and dynamic as the last ten.