Introduction
Mention the term demolition to almost any person and the scene that instantly comes to mind is a vision of a building being blown up and collapsing to the ground. Many people have claimed they would really like to press the button, to detonate the explosive units that bring a disused building to the ground. Most of the time what comes down, must go up and we are seeing many unsightly properties being taken down making way for potential future development, usually within a regeneration project.
For companies that over many years have built their business within the demolition of architectural structures, the demolition market is now considerably more reaching than just blowing up outdated buildings. When the property is demolished the massive task of site clearance starts and in a modern world where consideration of the environmental impacts are ever increasing on many peoples agenda, the material residues provided by demolition ought to be separated for recycling purposes. This will include such products as steel, wood, plastic, brickwork and concrete.
Almost all of the materials are bulked up and sent into the appropriate recycling plants for reprocessing. Resources such as bricks and concrete are usually crushed and turned into a recycled concrete aggregate substance available for reuse in the construction of new roads or structures. Ever more though, through breakthroughs in technological development, residues like concrete to be recycled must meet an extremely high specification for reuse in construction projects.
When crushed, the assorted sizes of recycled aggregate will govern the likely usage potential of the product. Large sizes might be used as decorative rockery products in landscaping whilst much finer, almost shingle like product can be used as a bedding for pipe laying or as a layer in highway construction. With an ever-increasing amount of opportunities recognized for the reuse of recycled aggregate, the whole demolition and construction market is generating a substantial contribution to sustainable development. Following demolition of a site, many demolition contractors have expanded their service offering to include site clearance services.
Reasons For the Increased Concentration on Recycling from Construction and Demolition Projects
In 1996, UK Government imposed a levy on all wastes going to landfill. The duty is paid on top of typical gate fees for waste material being disposed in landfill and since its introduction the cost has increased annually. When first introduced, the typical level of duty for general waste products being sent to landfill was �7 per tonne and �2 per tonne for inert products. The duty was created to persuade commercial and industrial businesses and local authorities collecting from properties, to divert waste away from landfill for recycling. In April 2009, the common rate of landfill duty rose to �40 per tonne and is scheduled to rise each year by �8 per tonne until 2013. The lower rate of duty incurred upon any inert materials going to landfill for example concrete and soils, has stayed reasonably stable in recent years and is currently at �2.50 per tonne.
However, the weight of a bulk load of these inert products going directly to landfill will guarantee that the full cost of disposal becomes extremely expensive and so even in the demolition and construction sector, diverting waste from landfill is a priority.
Most companies in the industry have extended their business to offer services as demolition and site clearance contractors, to make available the full range of services.
The next time you see a demolition project in progress or pass any construction site during a build programme, it’s clear to see the amount of waste material being created. If waste material isn’t in skips, heaps of rubble will be stacked high. The placing of construction waste materials in skips has been a major issue for waste contractors for several years. Having been an employee within the waste industry, I’ve seen skip lorries tipped backwards with the cab of the vehicle up in the air, a result of the sheer overloading of waste skips with construction site waste.
Each and every year, the uk produces close to 330 million tonnes of waste material and it is estimated that around 90 million tonnes of this is coming from building and demolition wastes. This figure has stayed fairly constant since 2001. About two thirds of this waste is normally recycled or reused in land reclamation or agricultural improvement projects. Ever since the late 1990s there has been a steady increase in the volumes of construction waste materials being recycled and this has been aided by advances in technology which have led to improved crushing solutions to make more widespread use of various grades of recycled aggregates.
In recent years, the construction industry in general has worked hard to motivate construction project supervisors to place a larger focus upon recycling on site. This has resulted in a rise in the recycling of all inert materials from site.
Prior to the introduction of the landfill levy just about all construction site waste materials including bricks and concrete was bulked up and transferred to a landfill site for disposal. No deliberation was given to recycling. These day there are stringent regulations across the sector, in conjunction with an increase in environmental focus, and also the commercial rewards in making sure that this type of waste is now recycled. There is also better recognition of the vast array of business opportunities to re-use recycled aggregates in the construction process on future construction projects or in arenas such as landscaping or home and garden Do-it-yourself. Following the demolition process, together the waste concrete, bricks, masonry etc will likely be transformed into a recycled concrete aggregate. Recycling of aggregates has become a common process for demolition contractors.
To recycle concrete aggregate to a high grade and resalable product, it must be entirely free of other contaminants such as wood, paper, card, steel and other general waste materials. The final product must also comply with the specifications of British Standard BS 8500. The process of recycling the concrete can normally be achieved in one of two ways. Some demolition contractors will install a crushing system on the demolition site, whereas a lot of contractors will opt to move the waste to be recycled, back to their own premises for segregation for recycling or re-use. On projects where demolition and new construction is to occur at the same location, the contractor is very likely to place a crushing machine on site to escape incurring additional transportation costs in taking the material back to a sorting and crushing centre.
Approval from the local authority might be required ahead of site clearance contractors starting the task of demolishing a building.
The Increasing Interest in Top Quality Recycled Aggregate
Before starting the crushing procedure, it needs to be determined what the end product is to be used for to make sure that the recycled aggregate is to match the required standards. There’s huge requirement for recycled concrete aggregate to be used during the construction process. As a product, recycled aggregate can be utilised for nearly every type of concrete structural function, road surfacing or pipe laying project. Having passed through the crusher the pieces of aggregate can be separated by size. Bigger pieces can be retained as a cosmetic product for use in landscaping rockery projects, or they might be passed back through the crusher to be pummeled to a smaller size. The small bits of recycled aggregate might be suited to use as a gravel on new construction projects, road laying or driveways at home. The crushing devices are now capable of achieving top quality small aggregate grades such as the production of a 20-5mm gravel which can be bagged and used in the garden at home or purchased in bulk as part of projects involving new concrete production. The advances in technology mean that the recycling of aggregates for other uses such as a simple gravel product or for use in concrete products has greatly reduced the need to dig quarries to mine for gravel. Recycled aggregates have become a versatile reusable product and has eliminated the need for large volumes of a good material to be disposed of in landfill and therefore offer significant environmental benefits.
The need for good quality crushed aggregate is growing. There’s key standards in place that are targeted upon improving the recycled concrete aggregate industry. Through research and improvement, more widespread applications are being discovered for the employment of recycled aggregate. No longer is concrete, just concrete. What we are talking about now are many distinct grades of recycled aggregate, ranging from the large sections of aggregate to very precise 6f2 recycled concrete which can be used as a sub-base material for construction jobs, or 20-5mm recycled aggregate, which is a gravel and can be used in road construction or at home on driveways. As well as being used as a mix for highway construction, recycled aggregate is being used as bedding for pipe laying or base material prior to construction projects starting. In achieving such high quality grades the 20-5mm recycled aggregate can be used as an aggregate base in highway construction and the quality meets the specifications necessary to allow its reuse in concrete production.
On the list of important criteria when using recycled aggregate is selecting the best specification for the task. For example, when using 20-5mm coarse graded aggregate as a road foundation, the depth of the layer required must be determined to stand up to traffic flows. Traffic flow on a motorway is going to be significantly different to that of a country road. One good reason aggregate produced to a 20-5mm specification is commonly employed as a road base is that it helps good waterflow and drainage. Once the recycled aggregate is laid, suitable layers of asphalt or concrete can be laid over it to build the road surface.
Recently, in the UK we appear to have more rain than hot sunshine and for that reason the chosen aggregate must have the ability to withstand variances in temperature and conditions e.g. dampness for long periods, torrential downpours, long dry spells. With its good waterflow and drainage characteristics, the recycled 20-5mm product could be the appropriate choice for many sand and gravel applications including, pipe bedding, driveways and footpaths, landscaping, plus for use in ready mixed and precast concrete products.
It is always better to employ a company with specialist knowledge of building demolition procedures and site clearance experience.
Recycled Aggregates and the 2012 Olympics
In its bid for the 2012 Olympic Games, London placed sustainability as the focus of its bid. The bid team identified a major opportunity to increase awareness of climate change and the concerns that surround it, and bring it to the Globe’s attention. With the eyes of the Entire world observing, the Olympics provide a unique chance to communicate important messages about sustainability. Throughout the whole development of the Olympic project, there is a determination to make 2012 by far the most sustainable Olympic Games ever held. This focus began when setting up the design and build programmes for the amenities and venues, the transport links and network, the hosting of the Games themselves and will conclude by leaving behind a long lasting heritage of a sustainable environment.
Ever since London was awarded the Games, all partners involved in the development specifications, from the design of the Olympic Arena, the Olympic Village and transportation links between the venues have been encouraged upon guaranteeing the use wherever possible of sustainable resources. Across the entire Olympic build programme developers have worked hard to discover acceptable sustainable materials for use in the build programme. By the end of the whole project we will see some clearly visible cases of the use of sustainable products.
Similarly there will be many more that are much less visible, and furthermore, many which will be not visible at all. Some of those products which visitors to the games and its numerous sites won’t even think about how recycled aggregates are already employed as part of the overall construction project. However designers and specifiers of materials to be used in the build programme will be secure in the knowledge that they have selected sustainable products including, the most appropriate recycled aggregates as part of the project. With its recognized characteristics, let us hope that somewhere in the worldwide TV coverage the 20-5mm recycled aggregate gets a mention somewhere, somehow. Imagine being asked to supply recycled aggregate which meets a very specific 20-5mm clean material specification, to help build the 2012 Olympic Village.
Summary
How times have developed recently in the demolition and construction marketplace. Businesses have been required to change to meet demanding environmental standards. As with virtually any segment, new regulations and legislation determine the benchmarks to which your business must aspire, if it is to be successful.
Companies involved in the manufacturing of recycled concrete aggregate are not any different. These are generally categorised as processed materials and must conform to a particular product specification which can be used in the construction process. The standard BS8500-2 offers a full specification for the uses of recycled concrete aggregates in concrete, although with such a vast range of recycled aggregates an all encompassing specification for the use of these aggregates is yet to be determined. The most crucial thing is that the industry does not stand still and wait for the specifications to be finalised. The versatility of recycled aggregates means that demolition contractors operating crushing plants are seeking to identify markets through which to sell their recycled products. The advances in crusher technology and machinery has seen a big increase in the options now available in supplying large chunks of recycled aggregate for landscape gardening use in rockeries, down to a gravel type 20-5mm recycled aggregate with its good drainage qualities to be used in road construction and driveways. The demolition and construction industry now places sustainability at the forefront of its future development projects.