Demolition Recycling

Show promoters say IDREX 2000 will bring together users and suppliers of demolition and recycling equipment from around the world. It will also provide a preview of trends and techniques shaping the industry as it enters the new millennium.

With the possible exception of computing and telecommunications, few industries can claim to have undergone such a radical transformation as the demolition and recycling industry has experienced the past 25 years. High-reach hydraulic excavators and specialist attachments have superseded crawler cranes and wrecking balls; accidents and fatalities have been reduced and site safety has been increased and demolition contractors have become specialized experts in controlled dismantling and materials recycling.

Yet the evolution of this fast-changing industry is far from over, a fact demonstrated by the sheer volume of innovative products and techniques on display at IDREX 2000.

Green Field Depletion

With the steady depletion of available green field sites, majority of today’s urban construction is done on existing brown field sites. The work can, as a result, involve either the complete or partial redevelopment of the site and existing buildings. This, along with more stringent legislation and growing commercial and environmental pressures, has had a major impact on modern demolition methods. Today, demolition is more complex, contract periods shorter, legislation more demanding, and the competition tougher.

It is even misleading to use the word demolition to describe the industry today since most structures are no longer demolished, but carefully dismantled so that the materials can be recycled.

Age of the Excavator

To reflect these changing demands, today’s demolition contractors are turning increasingly to the use of hydraulic excavators as the most productive, cost efficient solutions to their equipment needs. Excavators and mini excavators are used for almost every job from dismantling roofs to breaking up and removing foundations, almost replacing the once dominant tracked loader and crawler crane and wrecking ball.

The shift towards the use of high-reach excavators has sparked a revolution in excavator design. Demolition specification machines are heavily modified to match the demands of the demolition site. Purpose-built booms offer the best possible combination of strength, height and lift capacity; a heavy duty undercarriage and additional counterweight provide a stable working platform; and hydraulic systems can be adjusted to match the flows and pressures to different attachments. To withstand the abrasion and impact damage of the modern demolition site, excavators are also offered with a heavy duty guarding package comprising belly guards, full length track guiding guards, fenders for the superstructure, and a cab protection package with a Falling Object Guard.

The working envelope of these machines, once confined by engineering limitations, now seems constrained only by the imagination of demolition contractors and machine designers. While the majority of today’s high-reach machines currently offer an upward reach of between 15 and 25 meters, larger units have already breached the psychological 40-meter (130 feet) barrier. Transport restrictions and workload notwithstanding, there seems little to prevent the development of the world’s first 50 meter reach hydraulic excavator. “The need to adopt more selective demolition techniques will increase the demand for machines that can take out material from parts of a building that are difficult to reach,” says European Demolition Association (EDA) managing director Mark Polman. “This kind of work requires adapted attachments. Sorting and recycling on the demolition site will require specialized machines that do not create additional noise and dust.”

Getting Attached

While the bucket remains the attachment of choice, the changing needs of the demolition contractor have spawned the development of a vast array of highly specialized hydraulic attachments. Used correctly, these work tools can convert a hydraulic excavator, mini excavator or skid steer loader into a highly versatile carrier; one that is capable of a multitude of diverse tasks throughout the demolition and recycling process.

In many low-level applications, the breaking out of concrete foundations for example, the demolition process begins with a hydraulic hammer mounted on excavators in the 12 to 100 ton class. Equally common is top-down techniques where mini excavators and skid steer loaders equipped with small, powerful hydraulic hammers are used to remove the upper floors of a high rise structure.

Once again, environmental pressures have affected the design of demolition attachments. The need for low noise operation has produced a growing trend towards the use of silenced or super-silenced hydraulic hammers while dust suppression is now an option offered by most leading hammer manufacturers.

Having removed the upper floors of a structure, the top-down technique requires using a super long reach excavator equipped with a cutter-crusher. These attachments have 360o free or powered rotation and are used to crush through concrete, bricks and blocks to dismantle walls and floor slabs. The use of powerful cutter blades also allows the cutter-crusher to slice through multiple steel reinforcing bar, angle and I-beam sections. In addition to providing a safe and efficient demolition method, the low noise, low vibration operation of the cutter-crusher attachment allows work in noise sensitive areas.

On-Site Recycling

The key to a successful recycling operation is effective segregation of materials and it is here that hydraulic pulverizers and grabs come into their own. Powerful jaws make them ideally suited for separating steel rebar from concrete and reducing the size of blocks. Also, pulverizers and grabs can be used for rehandling duties, picking up material for loading into trucks for removal from site or for feeding a crushing plant.

Increasing environmental awareness, more stringent legislation and the need to preserve valuable landfill space has forced many demolition contractors to look closely at the “waste” materials they generate. For many, this has resulted in the regular use of a wheel, track and skid-mounted recycle crushing plants. The benefits of a recycle crusher are many. From reducing material size to reducing vehicle movements to creating a valuable Type 1 material for resale, a recycling plant is increasingly considered a key part of the demolition contractor’s armory.

There are two schools of thought on the best type of crusher for recycling duties—jaw or impactor—and both have their benefits. An impactor is able to produce a Type 1 material in a single pass, can handle asphalt materials, and is well suited to applications where steel reinforcing bar might be present. A jaw crusher, meanwhile, copes equally well with steel rebar and is more resistant to the wear and tear of high abrasion applications.

Each of these mobile crushers will produce a range of materials from dust to larger grades, all of which can be segregated to ensure that valuable materials are retained for re-use or sale and waste is separated for disposal.

In the past, such finite segregation would have taken place at a purpose-built and potentially expensive recycling plant. Today, however, with the introduction of small mobile screens, this process is equally likely to take place on the actual demolition site, where space allows. Used in conjunction with a small mobile crusher, these wheel, track and skid-mounted screens are an increasingly common sight on demolition contracts around the world.

Looking Ahead

The demolition process has undergone such a remarkable change in the past 25 years that the crawler crane and drop ball exponents of the 1970s that helped pioneer modern techniques would scarcely recognize the industry they helped to create. So what does the new Millennium hold for the demolition and recycling industry?

Safety and worker welfare will be high on the agenda for future industry development. It is only a matter of time before a pan-European safety standard is instigated to promote good working practice. Ultimately, this could form the basis of a global standard thanks, in part, to the strong working links between the EDA in Europe and the NADC in the US. “Safety is a subject that is far too important to be fragmented between governing bodies. Industries in both global regions are willing to exchange information and let contractors learn from each other as much as possible,” says Polman. “The NADC recently issued a new edition of their Safety Manual and the EDA exploring the into possibility of bringing this reference book to Europe.”

It seems that environmental concerns that helped shape the machines and methods of today will continue to the foreseeable future.

Legislation and taxation encouraging the use of recycled materials rather than virgin aggregates seems certain to spread and become more stringent. A draft European Community recommendation is currently circulating among member states and it is hoped that this will be taken to the next stage by spring 2001. It is also possible the world may follow the example of countries like Switzerland where contractors must prove materials cannot be recycled before they are allowed to be landfilled. This appears long overdue. Current estimates suggest 2.5 billion tons of demolition waste is being produced worldwide annually. “In the European Union alone, the demolition industry produces about 180 million tons of waste and, according to the recent Symonds Report, only 28% of this is actually being recycled,” says Polman. “Studies in this area show big regional differences in the amount of recycled material. Some countries achieve recycling rates of about 80%, but other European countries are well below 10%. European legislation is likely to demand that the average rate of 28% should rise to 80%.

Future machines will be quieter and equipment like hydraulic hammers, cutter-crushers and recycle crushing plants will benefit from reduced noise and improved dust suppression. Having become extremely adept at dismantling structures built in the 1950s, 60s and 70s, contractors will also have to adapt to meet the very specific challenges posed by the modular construction structures of the 1980s and 90s. This could new skills as well as the use of yet-to-be designed attachments developed as much for manipulating and handling as for breaking and cutting. “In the future, the construction industry will have to work with future demolition and recycling in mind,” Polman says. “Dangerous materials must be avoided and the construction has to allow re-use of materials that can be separated easily.”

The future is also likely to see a redressing of the workload balance between the initial soft strip and the physical structure dismantling. Currently, the soft strip is a labor intensive process that can take up to five times as long as the real bulk of the demolition contract. Experts suggest that the use of compact, sub-one ton mini excavators and skid steer loaders equipped with specialist attachments might be able to reduce considerably this time scale.

Fundamental Changes

But the challenges facing demolition contractors might be even more fundamental than merely addressing public concern for the environment and the labor intensity of specific tasks.

A worsening skills shortage throughout the industry will need to be addressed with a concerted training program and an initiative to attract young people to the sector. Public perception of the demolition industry must also improve if it is to attract the level and standard of new blood it needs. “Contractors must adapt their company and employees to higher quality standards concerning special treatment of dangerous materials like heavy metals, gypsum, isolation fibres and asbestos. In order to cope with requirements regarding selective demolition, sorting and recycling, companies will have to reconsider their site management, infrastructure and training schemes,” Polman says. “More than ever before, demolition contractors will need skilled and motivated employees who are able to adapt to future changes in the industry.”

Also a concern is the future workload for demolition and recycling contractors. On the one hand, brown field sites that are converted into much-needed living and commercial space are unlikely to require any further demolition work for as much as 30 years. And when these new steel frame and partition wall structures are eventually dismantled, the amount of demolition work and reusable materials created will be minimal. On the other hand, demolition will be a more complex and demanding process in the future. This change will require further research, training, preparation and the introduction of new techniques.

Despite these concerns, the demolition and recycling industry remains an innovative business in the midst of an exciting period of transition. It is difficult to predict precisely what the future holds for the contractors and suppliers serving this sector. But the direction is clear and IDREX 2000 exhibition will provide a timely sneak preview of the shape of things to come.

Further information on IDREX 2000 can be obtained by contacting the IDREX 2000 Information Centre, Advertising & Marketing Solutions Ltd., Milroy House, Sayers Lane, Tenterden, Kent, TN30 6BW, England, Tel: +44 (0)1580-767720; E-mail: abarker@amsolutions.co.uk.

This article was provided by the promoters of the IDREX 2000 exhibition.