Introduction
Mention the word demolition to almost anyone and the picture that promptly comes to mind is usually a vision of a structure being blown up and collapsing to the floor. A lot of people have claimed that they would really like to press the button, to trigger the explosive units that bring a disused structure to the ground. On most occasions the thing that comes down, must go up so we are witnessing many dilapidated structures being razed to make way for future development, often within a regeneration project.
For firms who over many years have created their business around the demolition of buildings, the demolition industry is now much more reaching than simply demolishing unwanted buildings. After the building is demolished the huge task of site clearance starts and in a world where consideration of the environmental impacts are ever increasing on many peoples agenda, the material remains provided by demolition need to be sorted for recycling purposes. This tends to include such products as steel, wood, plastic, brickwork and concrete.
Almost all of the materials tend to be bulked up and shipped to the appropriate recycling plants for reprocessing. Resources such as bricks and concrete are usually crushed and turned into a recycled concrete aggregate product ready for reuse in the making of new roadways or structures. Ever more though, via breakthroughs in technological development, residues including rubble to be recycled need to meet a very high standard for reuse in construction projects.
When crushed, the different sizes of recycled aggregate will govern the likely usage potential of the product. Large sizes could possibly be employed as decorative rockery products in gardening whilst much finer, almost shingle like product can be used to provide a bedding for pipe laying or for a layer in street construction. Through an increasing variety of options recognized for the reuse of recycled aggregate, the entire demolition and construction market is generating a considerable contribution to sustainable development.
Reasons For the Increased Concentration on Recycling from Construction and Demolition Projects
In 1996, UK Government added a tax on all wastes going to landfill. The levy is paid out in addition to standard gate rates for waste material being disposed in landfill and since its launch the cost has risen annually. When it was first introduced, the common rate of duty for general waste products going to landfill was �7 per tonne and �2 per tonne for inert products. The duty should encourage commercial and industrial businesses and local authorities collecting from properties, to divert waste away from landfill for recycling. In April 2009, the common level of landfill tax grew to �40 per tonne and is also timetabled to rise every year by �8 per tonne until 2013. The lower rate of duty incurred upon any inert materials going to landfill like concrete and soils, has stayed comparatively steady recently and is currently at �2.50 per tonne.
Nonetheless, the weight factor alone of a bulk load of inert products going directly to landfill will ensure 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 arrival of landfill tax has been a key driver in encouraging greater diversion of inert materials from landfill, to be used in sustainable development projects.
Most companies in the market have extended their business to offer services as demolition and site clearance contractors, to make available the full range of services.
The next time you see a demolition project in progress or go past almost 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 brick waste material in skips has been a serious problem for waste companies for several years. Having been an employee within the waste industry, I’ve seen skip lorries tipped backwards with the cab of the vehicle up in the air, because of the sheer overloading of waste skips with construction site waste.
Every year, the uk generates around 330 million tonnes of waste and approximately 90 million tonnes of this is from building and demolition wastes. This figure has stayed reasonably steady since 2001. About 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 gradual increase in the quantities of construction waste material being recycled and this has been helped by developments in technology that have resulted in improved crushing solutions to create more widespread use of varying specifications of recycled aggregates. There is a real focus upon the United Kingdom construction industry to encourage greater recycling of waste material on site.
In the past few years, the construction industry as a whole has worked hard to persuade construction site supervisors to put a greater emphasis upon recycling on site. This has led to an increase in the recycling of all inert materials from site.
Before the introduction of the landfill levy just about all construction site waste material including bricks and concrete would be bulked up and transported to a landfill site for disposal. No regard was given to recycling. Nowadays there are stringent limitations across the sector, in conjunction with an increase in environmental focus, and also the commercial advantages in making sure that this type of waste is recycled. There is also increased recognition of the wide array of business opportunities to use recycled aggregates in the construction process on alternative construction projects or in arenas 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 grade and resalable product, it needs to be completely free from other debris such as wood, paper, card, steel and other general waste materials. The end product also needs to conform to the requirements of British Standard BS 8500. The process of recycling the concrete can usually be achieved in one of two ways. Some demolition companies will install a crushing device on the demolition site, whereas various contractors will opt to carry the waste to be recycled, to their own 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 likely to locate a crushing appliance on site to avoid incurring extra transportation costs in taking the materials back to a sorting and crushing facility.
Check the credentials of prospective building demolition contractors before confirming their appointment to undertake your project.
The Increasing Interest in Top Quality Recycled Aggregate
Before starting the crushing procedure, it needs to be determined what the end product is to be used for to ensure that the recycled aggregate is to meet the required standards. There is huge demand for recycled concrete aggregate to be used within the construction process. As a product, recycled concrete aggregate can be utilised for just about any form 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 cosmetic product to use in garden rockery projects, or they might be passed back through the crusher to be crushed to a reduced 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 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 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 interest in top quality crushed aggregate is increasing. There’s key standards in place which are focused upon improving the recycled concrete aggregate sector. By means of research and improvement, more widespread uses are being identified for the use of recycled aggregate. No more 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 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 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 footing material prior to construction projects commencing. In achieving such top quality grades the 20-5mm recycled aggregate can be utilised as an aggregate base in highway building and the quality meets the standards necessary to allow its reuse in concrete production. The 20-5mm recycled aggregate is a very versatile product.
One of several important criteria when you use recycled aggregate is choosing the best specification for the task. By way of example, when making use of 20-5mm coarse graded aggregate as a road foundation, the thickness of the layer demanded needs to be determined to withstand 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 over it to build the road surface.
Recently, in the United Kingdom we appear to have more bad weather than hot sunshine and as a consequence the chosen aggregate must have the ability to endure variances in temperatures and conditions e.g. dampness for very long periods, torrential downpours, long dry spells. With its good waterflow and 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, and also for use in ready mixed and precast concrete products.
Where sustainability is a key focus of a construction project, the use of specified recycled concrete products offers a sustainable concrete solution.
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 raise awareness of climate change and the challenges that encircle it, and bring it to the Globe’s attention. With the eyes of the Entire world observing, the Olympic Games provide an exceptional opportunity to communicate important messages with regards to sustainability. During the whole development of the Olympic project, there exists a determination to make 2012 by far the most sustainable Olympic Games ever held. This focus originated when preparing 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 heritage of a sustainable environment.
Ever since London was granted the Games, all companies involved in the development specifications, from the design of the Olympic Arena, 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 architects have worked hard to discover appropriate 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. One of those products which visitors to the games and its countless locations won’t even consider how recycled aggregates are already specified as part of the overall construction project. But designers and specifiers of resources 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 aggregates as part of the project. With its recognized qualities, let us hope that somewhere in the world wide Television coverage the 20-5mm recycled aggregate gets a mention somewhere, somehow.
Summary
How times have developed recently for the demolition and construction sector. Firms have been required to adjust to meet tough green specifications. As with just about any market, new regulations and legislation dictate the benchmarks to which your business must aspire, if it is to achieve success.
Companies engaged in the generation of recycled aggregate are no 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 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 for use in highway construction and driveways.