Introduction
Mention the phrase demolition to just about anyone and the picture that instantly comes to mind is a vision of a building being blown up and collapsing to the floor. A lot of people have said they would love to press the button, to trigger the explosive systems which will bring a disused structure to the ground. On many occasions what comes down, must go up and we are seeing many empty structures being demolished making way for future development, usually together with a regeneration project.
For firms who over several years have built their business within the demolition of properties, the demolition arena has become far more reaching than just demolishing old buildings. Once the structure is demolished the tremendous task of site clearance starts and in a world where consideration of the environmental effects are ever increasing on most peoples agenda, the material remains coming from demolition should be separated for recycling applications. This tends to include such materials as steel, wood, plastic, brickwork and concrete.
Most of the materials tend to be bulked up and sent to appropriate recycling plants for reprocessing. Resources such as bricks and concrete can be crushed and become a recycled concrete aggregate substance ready for reuse in the construction of new highways or buildings. Ever more though, by means of breakthroughs in technological development, residues such as concrete to be recycled need to meet a very high specification for reuse in construction projects.
When crushed, the various sizes of recycled aggregate will govern the likely usage potential of the product. Large sizes might be employed as ornamental rockery products in gardening whilst much finer, shingle like product may be used to provide a bedding for pipe laying or for a layer in road construction. With an ever-increasing number of possibilities identified for the reuse of recycled aggregate, the entire demolition and construction market 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 imposed a tax on all wastes going to landfill. The levy is paid in addition to typical gate charges for waste material being disposed in landfill and since its initial release the cost has risen annually. When first introduced, the standard level of tax for general waste materials being sent to landfill was �7 per tonne and �2 per tonne for inert substances. The tax was designed to inspire commercial and industrial companies and local authorities collecting from properties, to divert waste away from landfill for recycling. In April 2009, the typical rate of landfill tax increased to �40 per tonne and is also timetabled to rise each year by �8 per tonne until 2013. The reduced level of tax incurred upon any inert materials going to landfill for example concrete and soils, has stayed relatively steady in recent years and is currently at �2.50 per tonne.
However, the weight factor alone of a bulk load of these inert products going direct to landfill will guarantee that the whole cost of disposal becomes extremely expensive and so even in the demolition and construction arena, diverting waste from landfill is a priority.
The initial stage of many new build projects requires companies to identify and adere to the particular demolition legislation relating to the property before construction work can begin.
Next time you see a demolition project in progress or pass any construction site during a build programme, it will be 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 rubble waste in skips has been a serious concern for waste contractors for many years. Having worked within the waste sector, I’ve seen skip lorries tipped backwards with the cab of the vehicle up in the air, because of the gross overloading of waste skips with building site waste.
Each year, the united kingdom generates close to 330 million tonnes of waste and approximately 90 million tonnes of this is coming from construction and demolition wastes. This number has remained reasonably constant since 2001. Close to two thirds of this waste is generally recycled or reused in land reclamation or agricultural development projects. Ever since the late 1990s there has been a steady rise in the quantities of construction waste material being recycled and this has been helped by developments in technology which have led to improved crushing products to create more common use of varying grades of recycled aggregates.
In the past few years, the construction sector as a whole has worked hard to persuade construction project supervisors to put a larger emphasis upon recycling on site. This has led to a growth in the recycling of all inert materials from site.
Before the introduction of the landfill duty all construction site waste including bricks and concrete would be bulked up and transferred to a landfill site for disposal. No deliberation was given to recycling. Nowadays there are stringent limitations across the sector, in conjunction with an increase in environmental focus, and also the commercial benefits in making certain that this kind of waste is now recycled. Addititionally there is better recognition of the vast array of business opportunities to use recycled aggregates within the construction process on alternative construction projects or in environments such as landscaping or home and garden DIY. Following the demolition process, together the waste concrete, bricks, masonry etc will likely 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 contaminants such as wood, paper, card, steel and other general waste materials. The end product also needs to comply with the requirements of British Standard BS 8500. The process of recycling the concrete can normally be achieved in one of two ways. Some demolition contractors will transport a crushing machine on the demolition site, whereas a lot of contractors will choose to carry the waste to be recycled, back to their premises for sorting for recycling or re-use. On projects where demolition and new construction is to take place at the same location, the contractor is likely to place a crushing machine on site to avoid incurring extra transportation costs in taking the materials back to a sorting and crushing centre.
For most demolition projects a building demolition contractor must complete good assessment of the challenges involved.
The Growing Interest in 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 is huge requirement for recycled aggregate to be used within the construction process. As a product, recycled concrete aggregate can be utilised for virtually any type of concrete structural function, road surfacing or pipe laying project. Having passed through the crusher the pieces of aggregate can be sorted by size. Bigger pieces may be retained as a decorative product for use in garden rockery projects, or they might be passed back through the crusher to be pummeled to a reduced size. The smaller sized pieces of recycled aggregate might be suitable for use as a gravel on new construction projects, road laying or driveways at home. The crushing devices are now capable of achieving high 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.
The need for top quality crushed aggregate is ever-increasing. There’s key standards in position which are concentrated upon improving the recycled aggregate market. By means of research and development, more widespread uses are being discovered for the use of recycled aggregate. No longer is concrete, just concrete. What we are talking about now a variety of distinct 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. In addition to 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 utilised as an aggregate base in road construction and the quality meets the specifications required to allow its reuse in concrete production. The 20-5mm recycled aggregate is a very versatile product.
One of the important requirements when you use recycled aggregate is choosing the correct specification for the task. For example, when making use of 20-5mm coarse graded aggregate as a highway base, the depth of the layer demanded needs to be determined to tolerate 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 assists good waterflow and drainage. Once the recycled aggregate is laid, appropriate layers of asphalt or concrete can be laid across it to form the road surface.
In recent years, in the United Kingdom we appear to have more bad weather than sunshine and therefore the selected aggregate must have the capacity to endure variances in temperature and conditions e.g. dampness for long periods, torrential downpours, long dry spells. With its good drainage characteristics, the recycled 20-5mm product is the ideal choice for a lot of sand and gravel applications including, pipe bedding, driveways and footpaths, landscaping, and also for use in ready mixed and precast concrete products.
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 Olympics
In its bid for the 2012 Olympic Games, London placed sustainability as the focus of its bid. The bid team recognized a big opportunity to raise awareness of climate change and the concerns which surround it, and bring it to the Globe’s attention. With the eyes of the World observing, the Olympics present an exceptional opportunity to put across key messages regarding sustainability. During the entire growth and development of the Olympics project, there exists a responsibility to make 2012 by far the most sustainable Olympics ever held. This focus originated when planning the development and build programmes for the facilities and venues, the transportation links and network, the hosting of the Games themselves and will conclude by leaving a long lasting legacy of a sustainable natural environment.
Ever since London was awarded the Games, all partners involved in the development specifications, from the construction of the Olympic Arena, the Olympic Village and transport links between the venues have been focused upon guaranteeing the use wherever possible of sustainable materials. 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 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 countless locations won’t even consider how recycled aggregates are already used as part of the overall construction project. But designers and specifiers of materials for use in the build programme will be secure in the knowledge that they have selected sustainable products which include, the most appropriate recycled aggregates as part of the project. With its identified qualities, let us hope that somewhere in the worldwide Television 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 in recent years for the demolition and construction business. Firms have had to adapt to meet tough green specifications. As with virtually any industry, new laws and legislation dictate the standards to which your business must aspire, if it is to be successful.
Firms involved in the production of recycled aggregate aren’t any different. These are 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 important 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.
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