A Guide to Recycled Concrete for the 2012 Olympic Village
Introduction
Mention the phrase demolition to almost anyone and the picture that immediately comes up is a vision of a building being blown up and collapsing to the floor. Lots of people have said they would really like to press the button, to trigger the explosive units which will bring a disused structure to the floor. In many cases the thing that comes down, must go up so we are seeing many old properties being demolished making way for future development, frequently within a regeneration project.
For businesses who over many years have created their business within the demolition of architectural structures, the demolition industry has become far more reaching than just demolishing old buildings. When the structure is demolished the huge task of site clearance begins and in a community where consideration of the environmental effects are very high on many peoples agenda, the material remains from demolition need to be sorted for recycling applications. This tends to include such products as steel, wood, plastic, brickwork and concrete.
Most of the materials tend to be bulked up and transported to the appropriate recycling plants for reprocessing. Products such as bricks and concrete can be crushed and become a recycled concrete aggregate substance ready for reuse in the making of new highways or buildings. More and more though, through advances in technological development, derivatives including concrete to be recycled need to meet a very high standard for reuse in construction projects.
When crushed, the various grades of recycled aggregate will govern the future usage potential of the product. Large sizes could be utilised as ornamental rockery products in landscaping whilst much finer, almost shingle like product can be utilised to provide a bedding for pipe laying or as a layer in road construction. Through an increasing variety of opportunities recognized for the reuse of recycled aggregate, the entire demolition and construction market is building 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 Concentration on Recycling from Construction and Demolition Projects
In 1996, UK Government added a duty on all waste items going to landfill. The levy is paid out in addition to regular gate fees for waste material being disposed in landfill and since its initial release the fee has increased annually. When first introduced, the common rate of duty for general waste materials going to landfill was �7 per tonne and �2 per tonne for inert substances. The duty is designed to persuade commercial and industrial organisations and local authorities collecting from properties, to divert waste away from landfill for recycling. In April ‘09, the typical rate of landfill tax grew to �40 per tonne and is timetabled to rise every year by �8 per tonne until 2013. The reduced level of tax charged upon any inert materials going to landfill like concrete and soils, has remained reasonably stable recently and is presently at �2.50 per tonne.
Nonetheless, the weight factor alone of a bulk load of inert materials going direct to landfill will guarantee that the entire cost of disposal becomes very expensive and so even in the demolition and construction sector, diverting waste from landfill is a priority.
The initial stage of many new build projects requires companies to identify and adere to the exact demolition legislation relating to the property before construction work starts.
Next time you see a demolition project in progress or pass any construction site during a build programme, it’s very clear to see the volume of waste material being created. If waste is not in skips, piles 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 worked in the waste industry, I have seen skip trucks tipped backwards with the cab of the vehicle up in the air, a result of the gross overloading of waste skips with building site waste.
Each and every year, the united kingdom generates around 330 million tonnes of waste material and approximately 90 million tonnes of this is from construction and demolition wastes. This figure has remained fairly constant since 2001. Close to 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 quantities of construction waste material being recycled and this has been assisted by developments in technology which have led to improved crushing technology to make more common use of varying grades of recycled aggregates.
In recent years, the construction sector as a whole has worked hard to motivate construction site managers to place a greater emphasis upon recycling on site. This has led to a growth in the recycling of inert materials from site.
Before the introduction of the landfill tax most construction site waste materials including bricks and concrete was bulked up and moved to a landfill site for disposal. No regard was given to recycling. There are now stringent restrictions across the sector, coupled with an increase in environmental focus, as well as the commercial advantages in ensuring that this kind of waste is now recycled. Addititionally there is significantly greater recognition of the large choice of potential opportunities to use recycled aggregates within 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 probably be transformed into a recycled concrete aggregate.
To recycle concrete aggregate to a high standard and resalable product, it needs to be totally free from other debris such as wood, paper, card, steel and other general waste materials. The final product also needs to comply with the requirements of British Standard BS 8500. The process of recycling the concrete can typically be achieved in one of two ways. Some demolition companies will locate a crushing unit on the demolition site, whereas some contractors will prefer to move the waste to be recycled, to their premises for separation 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 position a crushing unit on site to escape incurring added transportation costs in taking the material to a sorting and crushing centre. There is now very complex crushing equipment on the market to reduce concrete to a very fine specification.
Check the credentials of your building demolition companies before confirming their appointment to undertake your project.
The Growing Demand for High Quality Recycled Aggregate
Before starting the crushing procedure, it has to be determined what the end product will be used for to make sure that the recycled aggregate is to satisfy the necessary standards. There’s huge demand for recycled concrete aggregate to be used back in the construction process. As a product, recycled concrete aggregate can be utilised for almost any form of concrete structural work, road surfacing or pipe laying project. Having passed through the crusher the chunks of aggregate can be separated by size. Bigger pieces may be retained as a cosmetic product to use in garden rockery projects, or they could be passed back through the crusher to be pummeled to a smaller size. The smaller bits of recycled aggregate could 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 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 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 interest in good quality crushed aggregate is growing. There are key standards in place which are targeted upon improving the recycled aggregate industry. Through research and development, more widespread applications are now being identified 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 chunks 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 employed as a mix for highway construction, recycled aggregate is being used as bedding for pipe laying or foundation material prior to construction projects starting. 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 specifications necessary to allow its reuse in concrete production.
One of several important considerations when you use recycled aggregate is choosing the correct specification for your task. For example, when making use of 20-5mm coarse graded aggregate for a road foundation, the thickness of the layer needed must be determined to stand up to 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 employed as a road base is that it assists good drainage. Once the recycled aggregate is installed, appropriate layers of asphalt or concrete can be laid across it to construct the road surface.
In recent years, in the United Kingdom we seem to have more bad weather than hot sunshine and as a consequence the chosen aggregate must be able to withstand variances in temperature and conditions e.g. dampness for long periods, torrential downpours, long dry spells. With its good waterflow and drainage qualities, the recycled 20-5mm product may be the ideal choice for many sand and gravel applications including, pipe bedding, driveways and footpaths, landscaping, plus for use in ready mixed and precast concrete products. With its drainage qualities, 20-5mm recycled aggregate is a versatile product.
Demolition contractors look to produce recycled concrete material as part of the site clearance process, in making the site ready for redevelopment.
Recycled Aggregates and the 2012 Olympic games
In its bid for the 2012 Olympic Games, London placed sustainability as the focus of its bid. The bid team identified a big opportunity to boost awareness of climate change and the problems which surround it, and bring it to the World’s attention. With the eyes of the Entire world observing, the Olympics give an exceptional chance to convey key messages about sustainability. During the whole development of the Olympics project, there is a responsibility to make 2012 the most sustainable Olympics ever held. This focus began when setting up the design and build programmes for the facilities and venues, the transport links and network, the hosting of the Games themselves and will end by leaving a long lasting heritage of a sustainable healthy environment.
Since London was awarded the Games, all suppliers involved in the development requirements, from the construction of the Olympic Stadium, the Olympic Village and transportation links to 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 locate appropriate sustainable materials for use in the build programme. At the end of the overall project there will be some clearly visible examples 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. Some of those products which visitors to the games and its many locations will not even think about how recycled aggregates are already used as part of the overall construction project. But designers and specifiers of materials to be used within the build programme will be comfortable in the knowledge that they have selected sustainable products which include, the most appropriate recycled concrete aggregates as part of the project. With its identified characteristics, let’s hope that somewhere in the global TV coverage the 20-5mm recycled aggregate gets a reference somewhere, somehow.
Conclusion
How times have developed recently for the demolition and construction sector. Businesses have needed to adapt to meet tough green conditions. As with almost any segment, new laws and legislation determine the standards to which your company must aspire, if it is to be successful.
Firms involved in the manufacturing of recycled concrete aggregate are no 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 highway construction and driveways.
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