Introduction
Mention the word demolition to almost anyone and the image that promptly comes to mind is a vision of a structure being blown up and collapsing to the floor. Plenty of people have stated that they would really like to push the button, to detonate the explosive devices that bring a disused structure to the floor. Most of the time what comes down, must go up and we are witnessing many old properties being demolished making way for potential future development, usually together with a regeneration project.
For firms that over several years have built their business within the demolition of architectural structures, the demolition industry is now considerably more reaching than simply blowing up outdated buildings. Once the property is demolished the huge task of site clearance begins and in a community where consideration of the environmental impacts are high on most peoples agenda, the material remains as a result of demolition must be sorted for recycling applications. This can include such resources as steel, wood, plastic, brickwork and concrete.
Most of the materials tend to be bulked up and transported to appropriate recycling plants for reprocessing. Resources such as bricks and concrete can be crushed and become a recycled concrete aggregate product available for reuse in the making of new roadways or buildings. More and more though, by means of advances in technological development, derivatives including rubble to be recycled must meet an extremely high specification for reuse in construction projects.
When crushed, the varied sizes of recycled aggregate will govern the likely usage potential of the product. Large sizes could possibly be employed as cosmetic rockery products in gardening while much finer, almost shingle like product can be utilised as a bedding for pipe laying or for a layer in street construction. Through an increasing variety of options identified for the reuse of recycled aggregate, the entire demolition and construction market is generating 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 For the Increased Focus on Recycling from Construction and Demolition Projects
In 1996, UK Government added a duty on all waste items going to landfill. The duty is paid out in addition to regular gate charges for waste being disposed in landfill and since its launch the price has risen on an annual basis. When it was first introduced, the typical rate of tax for general waste materials being sent to landfill was �7 per tonne and �2 per tonne for inert substances. The tax was created to motivate commercial and industrial companies 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 is also timetabled to increase every year by �8 per tonne until 2013. The reduced rate of tax incurred upon any inert materials going to landfill for example concrete and soils, has stayed relatively steady recently and is presently at �2.50 per tonne.
Nevertheless, the weight factor alone of a bulk load of those inert products going directly to landfill will guarantee that the full cost of disposal becomes very expensive and so even in the demolition and construction arena, diverting waste from landfill is a priority.
Following demolition and after passing through the crushing operationrecycled 6F2 created from concrete and rubble from the demolished buildings can be used for several different purposes.
The next time you see a demolition project happening or pass just about any construction site during a build programme, it will be very clear to see the quantity of waste being generated. If waste is not in skips, heaps of rubble will probably be stacked high. The placing of concrete waste material in skips has been a serious problem for waste contractors for quite some time. I have worked within the waste industry, I have seen skip trucks tipped backwards with the cab of the vehicle up in the air, due to the gross overloading of waste skips with construction site waste.
Each and every year, the uk produces around 330 million tonnes of waste material and approximately 90 million tonnes of this is coming from construction and demolition wastes. This figure has stayed fairly constant since 2001. Approximately two thirds of this waste is generally recycled or reused in land reclamation or agricultural development projects. Ever since the late 1990s there’s been a steady rise in the quantities of construction waste material being recycled and this has been assisted by advances in technology which have resulted in improved crushing products to create more frequent use of various grades of recycled aggregates. There has been a real focus upon the UK construction sector to encourage greater recycling of waste material on site.
In recent years, the construction industry in general has worked hard to encourage construction project managers to place a larger focus upon recycling on site. This has resulted in a growth in the recycling of all inert materials from site.
Prior to 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. Nowadays there are stringent restrictions across the sector, in conjunction with an increase in environmental awareness, as well as the commercial benefits in making sure that this type of waste is recycled. Addititionally there is better recognition of the large choice of potential business opportunities to use recycled aggregates within the construction process on new 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. Recycling of aggregates has become a common process for demolition contractors.
To recycle concrete aggregate to a high standard and resalable product, it has to be totally free of other debris such as wood, paper, card, steel and other general waste materials. The end product must comply with the specifications of British Standard BS 8500. The process of recycling the concrete can typically be achieved in one of two ways. Some demolition companies will transport a crushing device on the demolition site, whereas various contractors will prefer to carry 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 occur at the same site, the contractor is very likely to locate a crushing appliance on site to escape incurring additional transportation costs in taking the materials to a sorting and crushing centre. There is now very advanced crushing equipment on the market to reduce concrete to a very fine specification.
Any conscientious demolition contractors work hard to recycle the maximum amount of waste as possible from the demolished building.
The Increasing Need for Top Quality Recycled Aggregate
Before starting the crushing procedure, it must be determined what the end product will be used for to make sure 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 aggregate can be used for just about any kind of concrete structural work, road surfacing or pipe laying project. Having passed through the crusher the pieces of aggregate can be sorted by size. Bigger pieces can be retained as a decorative product to use in landscaping rockery projects, or they may be passed back through the crusher to be crushed to a reduced size. The smaller 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 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 demand for top quality crushed aggregate is increasing. There’s key standards in position that are targeted upon improving the recycled aggregate industry. By means of research and improvement, more widespread applications are now 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, ranging from the large sections of aggregate to very specific 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. As well as being employed 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 high quality grades the 20-5mm recycled aggregate can be used as an aggregate base in road building and the quality meets the specifications necessary to allow its reuse in concrete production.
One of several important requirements when you use recycled aggregate is choosing the correct specification for your task. For instance, when using 20-5mm coarse graded aggregate as a road foundation, the depth of the layer needed needs to be determined to withstand traffic flows. Traffic flow on a motorway is going to 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 drainage. Once the recycled aggregate is installed, appropriate layers of asphalt or concrete can be laid over it to create the road surface.
In recent years, in the United Kingdom we appear to have more bad weather than hot sunshine and therefore the chosen 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 drainage qualities, the recycled 20-5mm product could be the ideal choice for a lot of sand and gravel applications including, pipe bedding, driveways and footpaths, landscaping, plus for use in ready mixed and precast concrete products.
It is always better to employ a company with specialist knowledge of building demolition procedures and site clearance experience.
Recycled Aggregates and the 2012 Olympics
In its bid for the 2012 Olympic Games, London placed sustainability as the focal point of its bid. The bid team recognized a significant opportunity to boost awareness of climate change and the issues which surround it, and bring it to the Globe’s attention. With the eyes of the Entire world watching, the Olympics present a unique chance to communicate important messages concerning sustainability. During the entire development of the Olympic project, there exists a commitment to make 2012 the most sustainable Olympic Games ever held. This focus originated when setting up the design and build programmes for the amenities and venues, the transportation links and system, the hosting of the Games themselves and will conclude by leaving behind a long lasting legacy of a sustainable natural environment.
Since London was granted the Games, all partners associated with the development specifications, from the construction of the Olympic Arena, the Olympic Village and transport links to the venues have been focused upon guaranteeing the use wherever possible of sustainable materials. Throughout the entire Olympic build programme developers have worked hard to locate suitable sustainable materials for use in the build programme. At the conclusion of the whole project there will be some clearly visible 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. Some of those products which visitors to the games and its countless locations will not even consider how recycled aggregates have been specified as part of the overall construction project. However designers and specifiers of resources to be used 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 identified qualities, let’s hope that somewhere in the worldwide 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.
Conclusion
How times have changed in recent years for the demolition and construction marketplace. Businesses have needed to adjust to meet tough environmental conditions. As with just about any segment, new regulations and legislation dictate the criteria to which your business must aspire, if it is to achieve success.
Businesses 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 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 supplying 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.