How to use Recycled Aggregates for the 2012 Olympics
Introduction
Mention the phrase demolition to just about anyone and the image that instantly comes to mind is usually a vision of a structure being blown up and collapsing to the floor. Lots of people have claimed that they would really like to press the button, to trigger the explosive systems that bring a disused building to the ground. Often what comes down, must go up so we are witnessing many dilapidated buildings being razed to help with making way for future development, normally together with a regeneration project.
For companies that over several years have built their business around the demolition of architectural structures, the demolition market has become considerably more reaching than simply blowing up outdated buildings. Once the building is demolished the massive task of site clearance will begin and in a community where consideration of the environmental effects are ever increasing on most peoples agenda, the material remains provided by demolition need to be separated for recycling applications. This tends to include such resources as steel, wood, plastic, brickwork and concrete.
The majority of the materials tend to be bulked up and sent into the appropriate recycling plants for reprocessing. Resources such as bricks and concrete are generally crushed and turned into a recycled concrete aggregate substance available for reuse in the making of new roadways or structures. Ever more though, through advancements in technological development, derivatives including concrete to be recycled must meet a very high standard for reuse in construction projects.
When crushed, the assorted sizes of recycled aggregate will determine the likely usage potential of the product. Larger sizes might be used as decorative rockery products in gardening while much finer, shingle like product may be used as a bedding for pipe laying or for a layer in highway construction. With an growing number of opportunities identified for the reuse of recycled aggregate, the whole demolition and construction industry is generating a significant 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 Focus on Recycling from Construction and Demolition Projects
In 1996, UK Government added a tax on all waste products going to landfill. The levy is paid out on top of standard gate rates for waste being disposed in landfill and since its introduction the cost has risen annually. When it was first introduced, the common rate of tax for general waste materials being sent to landfill was �7 per tonne and �2 per tonne for inert substances. The duty is designed to inspire commercial and industrial businesses and local authorities collecting from properties, to divert waste away from landfill for recycling. In April ‘09, the common rate of landfill duty rose to �40 per tonne and it is scheduled to increase annually by �8 per tonne until 2013. The lower rate of tax incurred upon any inert materials going to landfill for example concrete and soils, has stayed comparatively steady recently and is presently at �2.50 per tonne.
Nevertheless, the weight factor alone of a bulk load of those inert materials going direct to landfill will ensure that the whole cost of disposal becomes very expensive and so even in the demolition and construction sector, diverting waste from landfill is a top priority. The introduction of landfill tax has been a key driver in encouraging greater diversion of inert materials from landfill, to be used in sustainable development projects.
Having completed the initial step, demolition companies frequently bring crushing machinery on site to crush the brickwork and concrete remains.
Next time you see a demolition project in progress or pass just about any construction site during a build programme, it is very clear to see the amount of waste material being created. If waste isn’t in skips, piles of rubble will probably be stacked high. The placing of construction waste material in skips has been a major problem for waste contractors for quite some time. Having been an employee within the waste industry, I’ve seen skip trucks tipped backwards with the cab of the vehicle up in the air, because of the sheer overloading of waste skips with building site waste.
Every year, the united kingdom produces close to 330 million tonnes of waste materials and approximately 90 million tonnes of this is coming from construction and demolition wastes. This number has stayed reasonably steady since 2001. Approximately two thirds of this waste is normally recycled or reused in land reclamation or agricultural development projects. Since the later part of the 1990s there has been a gradual increase in the quantities of construction waste materials being recycled and this has been aided by developments in technology which have resulted in improved crushing products to make more widespread use of different grades of recycled aggregates.
In recent years, the construction sector in general has worked hard to persuade construction project managers to put a greater focus upon recycling on site. This has led to an increase in the recycling of all inert materials from site.
Prior to the introduction of the landfill duty almost all construction site waste including bricks and concrete was bulked up and moved to a landfill site for disposal. No deliberation was given to recycling. Nowadays there are stringent regulations across the sector, coupled with an increase in environmental consciousness, as well as the commercial advantages in ensuring that this type of waste is now recycled. Addititionally there is increased recognition of the wide array of opportunities to re-use recycled aggregates within the construction process on future construction projects or in fields such as landscaping or home and garden DIY. Following the demolition process, together the waste concrete, bricks, masonry etc will be transformed into a recycled concrete aggregate.
To recycle concrete aggregate to a high grade and resalable product, it needs to be totally free of other impurities such as wood, paper, card, steel and other general waste materials. The final product also needs to conform to the specifications of British Standard BS 8500. The task of recycling the concrete can typically be achieved in one of two ways. Some demolition companies will install a crushing unit on the demolition site, whereas some contractors will prefer to move the waste to be recycled, 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 likely to position a crushing appliance on site to avoid incurring added transportation costs in taking the materials to a sorting and crushing facility. There is now very sophisticated crushing equipment available to reduce concrete to a very fine specification.
For most demolition projects the building demolition contractor must complete a thorough assessment of the risks involved.
The Increasing Interest in Top Quality Recycled Aggregate
Before starting the crushing process, it must be determined what the end product will be used for to make sure the recycled aggregate is to meet the required standards. There is huge requirement for recycled aggregate to be used during the construction process. As a product, recycled concrete aggregate can be used for nearly every type of concrete structural function, road surfacing or pipe laying project. Having passed through the crusher the chunks of aggregate will be separated by size. Bigger pieces may be retained as a decorative product for use in landscaping rockery projects, or they might be passed back through the crusher to be crushed to a reduced size. The small pieces of recycled aggregate may 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 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 bought 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 high quality crushed aggregate is ever-increasing. There’s key standards in position which are concentrated upon improving the recycled aggregate sector. Through research and development, more widespread uses are being discovered for the employment of recycled aggregate. No longer is concrete, just concrete. What we are talking about now a wide range of different grades of recycled aggregate, which range 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 utilised in road construction or at home on driveways. In addition to being employed as a mix for road construction, recycled aggregate is being used as bedding for pipe laying or foundation material prior to construction projects commencing. In achieving such good quality grades the 20-5mm recycled aggregate can be used as an aggregate base in road construction and the quality meets the standards necessary to allow its reuse in concrete production. The 20-5mm recycled aggregate is a very versatile product.
On the list of important requirements when you use recycled aggregate is selecting the right specification for your task. For example, when using 20-5mm coarse graded aggregate for a road foundation, the thickness of the layer required will have to be determined to tolerate traffic flows. Traffic flow on a motorway is going to be significantly different to that of a country road. One reason aggregate produced to a 20-5mm specification is employed as a road base is that it helps good drainage. Once the recycled aggregate is installed, suitable layers of asphalt or concrete can be laid over it to create the road surface.
In recent years, in the United Kingdom we seem to have more rain than hot sunshine and as a consequence 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 drainage qualities, the recycled 20-5mm product is the appropriate 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.
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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 recognized a big opportunity to raise awareness of climate change and the concerns that surround it, and bring it to the Globe’s notice. With the eyes of the World watching, the Olympics present a unique chance to communicate key points concerning sustainability. During the entire growth and development of the Olympic project, there’s a commitment 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 transportation links and network, the hosting of the Games themselves and will conclude by leaving behind a long lasting heritage of a sustainable environment.
Since London was granted the Games, all companies involved in the development requirements, from the building of the Olympic Stadium, the Olympic Village and transportation links between the venues have been focused upon ensuring the use wherever possible of sustainable materials. Across the entire Olympic build programme architects have worked hard to locate appropriate sustainable materials for use in the build programme. At the end of the whole project we will see some clearly visible examples of the use of sustainable products.
Equally 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 numerous sites won’t even think about how recycled aggregates are used as part of the overall construction project. However developers and specifiers of resources for use in the build programme will be comfortable in the knowledge that they have selected sustainable products which include, the most suitable recycled aggregates as part of the project. With its identified characteristics, let us hope that somewhere in the world wide Television coverage the 20-5mm recycled aggregate gets a reference somewhere, somehow.
Summary
How times have changed in recent years for the demolition and construction sector. Firms have had to change to meet tough environmental conditions. As with virtually any sector, new regulations and legislation dictate the standards to which your business must aspire, if it is to achieve success.
Companies involved in the generation of recycled concrete aggregate aren’t any different. These are generally 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 offering 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.
