Introduction
Mention the word demolition to almost anyone and the picture that instantly comes to mind is usually a vision of a structure being blown up and collapsing to the ground. A lot of people have said that they would love to push the button, to trigger the explosive devices which will bring a disused structure to the floor. On many occasions what comes down, must go up and we are witnessing many dilapidated properties being taken down making way for future development, often together with a regeneration project.
For businesses that over a number of have developed their business around the demolition of architectural structures, the demolition sector has become much more reaching than just blowing up outdated buildings. As soon as the structure is demolished the massive task of site clearance begins and in a community where consideration of the environmental effects are very high on a good number of peoples agenda, the material remains provided by demolition ought to be sorted for recycling reasons. This will likely include such resources as steel, wood, plastic, brickwork and concrete.
A lot of the materials are bulked up and shipped into the appropriate recycling plants for reprocessing. Materials such as bricks and concrete can be crushed and turned into a recycled concrete aggregate substance completely ready for reuse in the making of new roads or buildings. Increasingly though, through breakthroughs in technological development, residues like concrete to be recycled have to meet a high specification for reuse in construction projects.
When crushed, the assorted grades of recycled aggregate will govern the future usage potential of the product. Large sizes might be used as decorative rockery products in gardening whilst much finer, shingle like product can be utilised as a bedding for pipe laying or as a layer in highway construction. With an ever-increasing variety of possibilities identified for the reuse of recycled aggregate, the whole demolition and construction industry is generating a considerable contribution to sustainable development.
Reasons Behind the Increased Focus on Recycling from Construction and Demolition Projects
In 1996, UK Government added a levy on all waste items going to landfill. The tax is paid out on top of typical gate fees for waste material being disposed in landfill and since its initial release the cost has increased on an annual basis. When it was first introduced, the typical rate of tax for general wastes going to landfill was �7 per tonne and �2 per tonne for inert substances. The duty should persuade commercial and industrial firms and local authorities collecting from properties, to divert waste away from landfill for recycling. In April 2009, the standard level of landfill duty rose to �40 per tonne and it is timetabled to rise annually by �8 per tonne until 2013. The lower rate of tax incurred upon any inert materials going to landfill including concrete and soils, has stayed comparatively stable recently and is presently at �2.50 per tonne.
Nonetheless, the weight factor alone of a bulk load of these inert materials going directly to landfill will ensure that the full cost of disposal becomes extremely expensive and so even in the demolition and construction arena, diverting waste from landfill is a top priority.
The materials which remain after the use of the demolition equipment can be converted into a variety of reusable products to be used in other construction projects.
Next time you see a demolition project in progress or pass almost any construction site during a build programme, it’s very clear to see the volume of waste material being created. If waste material is not in skips, piles of rubble will probably be stacked high. The placing of rubble waste materials in skips has been a serious issue for waste companies for many years. Having worked in the waste sector, I have seen skip lorries tipped backwards with the cab of the vehicle up in the air, due to the sheer overloading of waste skips with construction site waste.
Each and every year, the united kingdom produces around 330 million tonnes of waste materials and it is estimated that around 90 million tonnes of this is from building and demolition wastes. This number has stayed relatively steady 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 being recycled and this has been assisted by developments in technology that have resulted in improved crushing solutions to make more frequent use of various grades of recycled aggregates. There’s been a genuine focus upon the United Kingdom construction industry to encourage greater recycling of waste materials on site.
In the past few years, the construction industry in general has worked hard to encourage construction project managers to put a larger emphasis upon recycling on site. This has resulted in a rise in the recycling of inert materials from site.
Before the introduction of the landfill levy almost all construction site waste material including bricks and concrete would be bulked up and transported to a landfill site for disposal. No consideration was given to recycling. These day there are stringent limitations across the sector, in conjunction with an increase in environmental awareness, as well as the commercial rewards in making sure that this type of waste is recycled. There is also significantly greater recognition of the vast array of opportunities to re-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 be transformed into a recycled concrete aggregate.
To recycle concrete aggregate to a high grade and resalable product, it has to be completely free of other debris such as wood, paper, card, steel and other general waste materials. The end product must comply with the requirements of British Standard BS 8500. The process of recycling the concrete can usually 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 prefer 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 location, the contractor is likely to position a crushing machine on site to avoid incurring additional transportation costs in taking the materials back to a sorting and crushing facility.
The crushing machinery UK demolition contractors apply will convert brick and concrete residues into recycled aggregate for future use.
The Growing Interest in High Quality Recycled Aggregate
Before starting the crushing process, it needs to be determined what the end product is to be used for to ensure that the recycled aggregate is to satisfy the required standards. There’s huge requirement for recycled concrete aggregate to be used back in the construction process. As a product, recycled concrete aggregate can be used for nearly every kind of concrete structural function, road surfacing or pipe laying project. Having passed through the crusher the pieces of aggregate will be separated by size. Bigger pieces may be retained as a cosmetic product to use in landscaping rockery projects, or they may be passed back through the crusher to be crushed to a smaller size. The smaller pieces of recycled aggregate may be suitable for use as a gravel on new construction projects, road laying or driveways at home. The crushing machines 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 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 interest in good quality crushed aggregate is growing. There are key standards in place which are concentrated upon improving the recycled concrete aggregate market. By means of research and improvement, more widespread applications are now being discovered for the employment of recycled aggregate. No more 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 specific 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 foundation 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 building and the quality meets the standards required to allow its reuse in concrete production.
On the list of important considerations when using recycled aggregate is choosing the correct specification for your task. For instance, when making use of 20-5mm coarse graded aggregate as a road base, the thickness of the layer required must be determined to tolerate traffic flows. Traffic flow on a motorway will be significantly different to that of a country road. One reason aggregate produced to a 20-5mm specification is used as a road base is that it assists good waterflow and drainage. Once the recycled aggregate is installed, appropriate layers of asphalt or concrete can be laid over it to form the road surface.
Recently, in the United Kingdom we seem to have more rain than sunshine and for that reason the selected aggregate must have the ability to tolerate 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 may be the ideal choice for some 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 versatile product.
Crushing machines are capable of producing good quality recycled concrete which can be used for a variety of purposes.
Recycled Aggregates and the 2012 Olympic games
In its bid for the 2012 Olympic Games, London set sustainability as the focus of its bid. The bid team identified a big opportunity to raise awareness of climate change and the issues which surround it, and bring it to the World’s attention. With the eyes of the World observing, the Olympics present an exceptional opportunity to get across key points concerning sustainability. During the entire development of the Olympic project, there’s a responsibility to make 2012 the most sustainable Olympics ever held. This focus originated 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 legacy of a sustainable healthy environment.
Since London was granted the Games, all companies associated with the development requirements, from the design of the Olympic Stadium, the Olympic Village and transport links between the venues have been focused upon ensuring the use wherever possible of sustainable materials. Across the entire Olympic build programme construction managers have worked hard to identify acceptable sustainable materials for use in the build programme. By the end of the whole project we will see some clearly obvious 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. One of those products which visitors to the games and its many sites will not even think about how recycled aggregates have been employed as part of the overall construction project. But designers and specifiers of resources to be used in the build programme will be comfortable in the knowledge that they have selected sustainable products including, the most appropriate recycled aggregates as part of the project. With its identified characteristics, let us hope that somewhere in the global TV coverage the 20-5mm recycled aggregate gets a reference 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.
Conclusion
How times have developed in recent years for the demolition and construction marketplace. Organisations have had to change to meet challenging green conditions. As with just about any segment, new regulations and legislation determine the criteria to which your company must aspire, if it is to achieve success.
Companies engaged in the production of recycled aggregate aren’t 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 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. The demolition and construction industry now places sustainability at the forefront of its future development projects.
Wrought Iron Gates