Introduction
Mention the word demolition to almost anyone and the scene that instantly comes to mind is usually a vision of a building being blown up and collapsing to the ground. Lots of people have claimed that they would love to press the button, to detonate the explosive units that bring a disused structure to the ground. In many cases the thing that comes down, must go up so we are seeing many old buildings being taken down to help with making way for future development, usually during a regeneration project.
For firms who over several years have established their business around the demolition of architectural structures, the demolition arena is now considerably more reaching than just demolishing unwanted buildings. As soon as the property is demolished the tremendous task of site clearance will begin and in a society where consideration of the environmental impacts are high on many peoples agenda, the material residues as a result of demolition should be separated for recycling applications. This tends to include such resources as steel, wood, plastic, brickwork and concrete.
Most of the materials can be bulked up and transported to appropriate recycling plants for reprocessing. Products such as bricks and concrete can be crushed and turned into a recycled concrete aggregate product ready for reuse in the making of new roadways or buildings. Ever more though, by means of breakthroughs in technological development, residues such as rubble to be recycled must meet a very high standard for reuse in construction projects.
When crushed, the different grades of recycled aggregate will govern the likely usage potential of the product. Large sizes might be utilised as cosmetic rockery products in landscaping while much finer, almost shingle like product may be used to provide a bedding for pipe laying or as a layer in street construction. Through an increasing amount of possibilities identified for the reuse of recycled aggregate, the whole demolition and construction industry is making a considerable contribution to sustainable development. Following demolition of a site, many demolition contractors have expanded their service offering to include site clearance services.
Reasons Behind the Increased Concentration on Recycling from Construction and Demolition Projects
In 1996, UK Government added a tax on all waste items going to landfill. The duty is paid in addition to normal gate fees for waste being disposed in landfill and since its introduction the fee has risen on an annual basis. When first introduced, the standard rate of tax for general waste products being sent to landfill was �7 per tonne and �2 per tonne for inert materials. The levy is designed to inspire commercial and industrial companies and local authorities collecting from properties, to divert waste away from landfill for recycling. In April ’09, the typical rate of landfill duty grew to �40 per tonne and is scheduled to rise annually by �8 per tonne until 2013. The reduced level of duty charged upon any inert materials going to landfill including concrete and soils, has remained comparatively steady recently and is presently at �2.50 per tonne.
However, the weight factor alone of a bulk load of those inert materials going straight to landfill will guarantee that the entire cost of disposal becomes horrendously expensive and so even in the demolition and construction arena, diverting waste from landfill is a top priority.
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The next time you see a demolition project in progress or go past just about any construction site during a build programme, it will be clear to see the quantity of waste being created. If waste material is not in skips, heaps of rubble will probably be stacked high. The placing of brick waste materials in skips has been a major concern for waste contractors for quite some time. Having been an employee within the waste industry, I have seen skip lorries tipped backwards with the cab of the vehicle up in the air, due to the gross overloading of waste skips with building site waste.
Each year, the united kingdom produces close to 330 million tonnes of waste and it is estimated that around 90 million tonnes of this is from construction and demolition wastes. This figure has stayed fairly constant since 2001. About two thirds of this waste is usually recycled or reused in land reclamation or agricultural development projects. Ever since the late 1990s there has been a gradual rise in the volumes of construction waste material being recycled and this has been assisted by developments in technology that have resulted in improved crushing technology to make more common use of different specifications of recycled aggregates. There is a real focus upon the UK construction sector to encourage more recycling of waste material on site.
In the past few years, the construction industry in general has worked hard to persuade construction site supervisors to place a greater emphasis upon recycling on site. This has led to an increase in the recycling of all inert materials from site.
Before the introduction of the landfill tax almost all construction site waste including bricks and concrete was bulked up and taken to a landfill site for disposal. No particular attention was given to recycling. These day there are strict restrictions across the sector, coupled with an increase in environmental consciousness, and also the commercial advantages in ensuring that this type of waste is now recycled. There is also increased recognition of the wide array of business opportunities to use recycled aggregates within the construction process on new construction projects or in environments such as landscaping or home and garden Do-it-yourself. Following the demolition process, together the waste concrete, bricks, masonry etc will probably 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 standard and resalable product, it must be entirely free of other contaminants such as wood, paper, card, steel and other general waste materials. The end product also needs to comply with the specifications of British Standard BS 8500. The process of recycling the concrete can usually be achieved in one of two ways. Some demolition contractors will install a crushing device on the demolition site, whereas a lot of contractors will choose to transport the waste to be recycled, back to their premises for separation for recycling or re-use. On projects where demolition and new construction is to take place at the same site, the contractor is very likely to position a crushing unit on site to avoid incurring additional transportation costs in taking the material to a sorting and crushing centre. There is now very advanced crushing equipment on the market to reduce concrete to a very fine specification.
Approval from the local authority will probably be required prior to site clearance contractors commencing the task of demolishing a building.
The Growing Need for Top Quality Recycled Aggregate
Before commencing the crushing procedure, it must be determined what the end product is to be used for to ensure that the recycled aggregate is to match the necessary standards. There is huge requirement for recycled concrete aggregate to be used within the construction process. As a product, recycled concrete aggregate can be utilised for just about any type of concrete structural work, road surfacing or pipe laying project. Having passed through the crusher the pieces of aggregate will be sorted by size. Bigger pieces can be retained as a cosmetic product to use in garden rockery projects, or they could be passed back through the crusher to be crushed to a reduced size. The small bits of recycled aggregate might be suitable for use as a gravel on new construction projects, road laying or driveways at home. The crushing units are now capable of achieving good 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 demand for top quality crushed aggregate is growing. There’s key standards in position that are concentrated upon improving the recycled concrete aggregate sector. By means of research and improvement, more widespread uses are now being identified for the employment of recycled aggregate. No longer is concrete, just concrete. What we are talking about now a variety of different grades of recycled aggregate, which range from the large sections of aggregate to very precise 6f2 recycled concrete which can be employed 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 commencing. In achieving such good quality grades the 20-5mm recycled aggregate can be utilised as an aggregate base in road building and the quality meets the specifications necessary to allow its reuse in concrete production.
On the list of important considerations when using recycled aggregate is selecting the best specification for your task. By way of example, when using 20-5mm coarse graded aggregate for a highway foundation, the thickness of the layer demanded needs to be determined to withstand traffic flows. Traffic flow on a motorway will 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 aids good waterflow and drainage. Once the recycled aggregate is installed, suitable layers of asphalt or concrete can be laid over it to build the road surface.
Recently, in the United Kingdom we appear to have more bad weather than sunshine and as a consequence the selected aggregate must have the capacity 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 perfect choice for many sand and gravel applications including, pipe bedding, driveways and footpaths, landscaping, and also for use in ready mixed and precast concrete products. With its drainage qualities, 20-5mm recycled aggregate is a useful product.
In matters as complex as demolition it is advised to retain a specialist company conversant with BREEAM and other demolition legislation www.eastmidlandsdemolition.co.uk is one such company that comes highly recommended.
Recycled Aggregates and the 2012 Olympic games
In its bid for the 2012 Olympic Games, London placed sustainability as the focal point of its bid. The bid team identified a significant opportunity to boost awareness of climate change and the problems which encircle it, and bring it to the World’s attention. With the eyes of the World observing, the Olympic Games present an exceptional chance to communicate important messages regarding sustainability. Through the entire growth and development of the Olympic project, there is a responsibility to make 2012 the most sustainable Olympic Games ever held. This focus originated when setting up the design and build programmes for the facilities and venues, the transport links and system, the hosting of the Games themselves and will end by leaving a long lasting legacy of a sustainable environment.
Ever since London was awarded the Games, all partners involved in the development requirements, from the building of the Olympic Arena, the Olympic Village and transport links between the venues have been encouraged upon guaranteeing the use wherever possible of sustainable materials. Throughout the entire Olympic build programme construction managers have worked hard to identify acceptable sustainable materials for use in the build programme. At the end of the whole project there will be some clearly obvious cases of the use of sustainable products.
At the same time there will be many more that are much less visible, and furthermore, many which will be not visible at all. One of those products which visitors to the games and its countless locations will not even think about how recycled aggregates are employed as part of the overall construction project. But developers and specifiers of resources for use 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 world wide 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 changed in recent years for the demolition and construction market. Businesses have needed to adjust to meet demanding green conditions. As with nearly every market, new laws and legislation dictate the standards to which your company must aspire, if it is to achieve success.
Businesses involved in the production of recycled concrete aggregate are not any different. These are classed 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 main 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 providing 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 for use in highway construction and driveways.