Introduction
Mention the term demolition to almost any person and the image that promptly comes up is often a vision of a building being blown up and collapsing to the floor. Lots of people have said that they would love to push the button, to trigger the explosive systems which bring a disused property to the ground. Often what comes down, must go up and now we are seeing many old properties being razed to make way for future development, generally as part of a regeneration project.
For firms that over a number of have built their business around the demolition of structures, the demolition arena has become much more reaching than just blowing up old and unwanted buildings. Once the building is demolished the massive task of site clearance starts and in a modern world where consideration of the environmental impacts are ever increasing on most peoples agenda, the material residues from demolition ought to be sorted for recycling applications. This will likely include such products as steel, wood, plastic, brickwork and concrete.
The vast majority of the materials tend to be bulked up and sent into the appropriate recycling plants for reprocessing. Products such as bricks and concrete are generally crushed and turned into a recycled concrete aggregate substance available for reuse in the construction of new roads or buildings. Increasingly though, by means of advancements in technological development, residues including rubble to be recycled must meet a high specification for reuse in construction projects.
When crushed, the assorted grades of recycled aggregate will determine the likely usage potential of the product. Larger sizes could be utilised as cosmetic rockery products in landscaping while much finer, shingle like product may be used to provide a bedding for pipe laying or for a layer in road construction. With an growing amount of opportunities recognized for the reuse of recycled aggregate, the whole 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 For 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 out on top of typical gate charges for waste material being disposed in landfill and since its launch the charge has increased on an annual basis. When first introduced, the common rate of tax for general waste products being sent to landfill was �7 per tonne and �2 per tonne for inert products. The levy is designed to encourage commercial and industrial businesses and local authorities collecting from households, to divert waste away from landfill for recycling. In April ’09, the standard rate of landfill duty grew to �40 per tonne and is timetabled to increase annually by �8 per tonne until 2013. The reduced level of duty charged upon any inert materials going to landfill like concrete and soils, has remained comparatively steady recently and is presently at �2.50 per tonne.
Nonetheless, the weight of a bulk load of those inert materials going straight to landfill will ensure that the entire cost of disposal becomes horrendously expensive and so even in the demolition and construction market, diverting waste from landfill is a top priority.
Having completed the initial work, demolition companies frequently bring crushing machinery on site to crush the brickwork and concrete remains.
Next time you see a demolition project happening or go past just about any construction site during a build programme, it’s obvious to see the quantity of waste material being created. If waste isn’t in skips, piles of rubble will be stacked high. The placing of brick waste material in skips has been a serious issue for waste contractors for several years. Having been an employee in the waste sector, 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.
Each 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 figure has remained fairly constant since 2001. About two thirds of this waste is usually recycled or reused in land reclamation or agricultural improvement projects. Ever since the late 1990s there has been a gradual increase in the quantities of construction waste being recycled and this has been aided by developments in technology that have resulted in improved crushing solutions to create more common use of various specifications of recycled aggregates. There is a real focus upon the United Kingdom construction sector to encourage more recycling of waste material on site.
In recent years, the construction sector in general has worked hard to persuade construction project supervisors to place a greater focus upon recycling on site. This has triggered a rise in the recycling of inert materials from site.
Prior to the introduction of the landfill levy all construction site waste including bricks and concrete was bulked up and taken to a landfill site for disposal. No thought was given to recycling. Nowadays there are stringent restrictions across the sector, coupled with an increase in environmental focus, and also the commercial advantages in making sure that this kind of waste is recycled. Addititionally there is significantly greater recognition of the wide array of business opportunities to use recycled aggregates within the construction process on alternative construction projects or in areas 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 must be completely free of 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 task of recycling the concrete can normally be achieved in one of two ways. Some demolition companies will locate a crushing device on the demolition site, whereas a lot of contractors will choose 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 take place at the same site, the contractor is very likely to locate a crushing appliance on site to avoid incurring additional 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.
Many established Nottingham demolition contractors also have extended their services to incorporate site clearance services.
The Growing Interest in High Quality Recycled Aggregate
Before commencing the crushing procedure, it has to be determined what the end product will be used for to make sure the recycled aggregate is to match the necessary standards. There’s huge requirement for recycled concrete aggregate to be used during the construction process. As a product, recycled 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 sorted by size. Bigger pieces can be retained as a cosmetic product for use in landscaping rockery projects, or they may be passed back through the crusher to be crushed to a smaller size. The small 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 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 demand for good quality crushed aggregate is ever-increasing. There’s key standards in position that are concentrated upon improving the recycled concrete aggregate industry. By means of research and improvement, more widespread applications are now being discovered 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 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 used 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 starting. In achieving such high quality grades the 20-5mm recycled aggregate can be utilised as an aggregate base in highway construction and the quality meets the specifications necessary to allow its reuse in concrete production. The 20-5mm recycled aggregate is a very versatile product.
On the list of important considerations when using recycled aggregate is choosing the best specification for your task. For instance, when using 20-5mm coarse graded aggregate as a highway base, the depth of the layer needed must be determined to withstand 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 drainage. Once the recycled aggregate is installed, suitable layers of asphalt or concrete can be laid across it to create the road surface.
Recently, in the UK we seem to have more bad weather than sunshine and therefore the selected aggregate must be able to endure variances in temperatures 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 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 set sustainability as the focal point of its bid. The bid team identified a big opportunity to increase awareness of climate change and the challenges that surround it, and bring it to the World’s attention. With the eyes of the Entire world observing, the Olympic Games give an exceptional chance to convey key messages regarding sustainability. Through the whole growth and development of the Olympics project, there exists a commitment to make 2012 by far the most sustainable Olympics ever held. This focus began when planning the development and build programmes for the amenities and venues, the transport links and system, the hosting of the Games themselves and will conclude by leaving a long lasting legacy of a sustainable healthy environment.
Since London was granted the Games, all partners involved in the development specifications, from the building of the Olympic Stadium, the Olympic Village and transport links between the venues have been focused upon ensuring the use wherever possible of sustainable resources. Throughout the entire Olympic build programme developers have worked hard to discover suitable sustainable materials for use in the build programme. At the conclusion of the overall project we will see some clearly obvious 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 many locations won’t even think about how recycled aggregates are already employed as part of the overall construction project. However 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 suitable recycled aggregates as part of the project. With its identified qualities, let’s hope that somewhere in the world wide 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.
Summary
How times have developed in recent years for the demolition and construction sector. Organisations have been required to adjust to meet tough environmental standards. As with almost any segment, new regulations and legislation determine the criteria to which your business must aspire, if it is to be successful.
Firms engaged in the generation of recycled concrete aggregate are not 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 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 for use in highway construction and driveways.
