Introduction

Mention the word demolition to just about anyone and the picture that immediately comes to mind is often a vision of a structure being blown up and collapsing to the ground. A lot of people have claimed they would really like to press the button, to trigger the explosive systems that bring a disused property to the ground. Most of the time what comes down, must go up and now we are seeing many empty buildings being demolished to make way for future development, frequently as part of a regeneration project.

For organizations that over several years have established their business within the demolition of properties, the demolition sector has become far more reaching than just demolishing unwanted buildings. Once the structure is demolished the huge task of site clearance starts and in a community where consideration of the environmental effects are high on a good number of peoples agenda, the material remains provided by demolition must be sorted for recycling reasons. This tends to include such resources as steel, wood, plastic, brickwork and concrete.

The majority of the materials are bulked up and transferred into the appropriate recycling plants for reprocessing. Materials 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. Ever more though, through breakthroughs in technological development, derivatives such as rubble to be recycled need to meet a high standard for reuse in construction projects.

When crushed, the various 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 may be used to provide a bedding for pipe laying or for a layer in road construction. With an ever-increasing number of opportunities identified for the reuse of recycled aggregate, the entire demolition and construction industry is making a considerable contribution to sustainable development.

Reasons For the Increased Concentration on Recycling from Construction and Demolition Projects

In 1996, UK Government imposed a duty on all wastes going to landfill. The tax is paid out on top of typical gate charges for waste material being disposed in landfill and since its launch the price has risen annually. When first introduced, the standard level of duty for general waste products going to landfill was �7 per tonne and �2 per tonne for inert products. The levy should inspire commercial and industrial firms 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 scheduled to rise each year by �8 per tonne until 2013. The lower level of tax incurred upon any inert materials going to landfill like concrete and soils, has stayed fairly stable in recent years and is currently at �2.50 per tonne.

Even so, the weight of a bulk load of inert products going directly to landfill will ensure that the full cost of disposal becomes very expensive and so even in the demolition and construction industry, 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.

The very first stage of many new build projects requires companies to identify and adere to the specific demolition legislation pertaining to the property before construction work can begin.

Next time you see a demolition project happening or pass almost any construction site during a build programme, it is clear to see the volume of waste being generated. If waste is not in skips, heaps of rubble will be stacked high. The placing of rubble waste material in skips has been a major concern for waste contractors for quite some time. Having worked in the waste industry, I have seen skip lorries tipped backwards with the cab of the vehicle up in the air, due to the gross overloading of waste skips with construction site waste.

Every year, the united kingdom generates close to 330 million tonnes of waste materials and approximately 90 million tonnes of this is coming from building and demolition wastes. This figure has stayed relatively steady since 2001. Around two thirds of this waste is normally recycled or reused in land reclamation or agricultural development projects. Ever since the late 1990s there’s been a steady rise in the volumes of construction waste materials being recycled and this has been assisted by developments in technology that have led to improved crushing technology to create more frequent use of varying grades of recycled aggregates.

In recent years, the construction industry in general has worked hard to persuade construction project managers to put a greater focus upon recycling on site. This has triggered an increase in the recycling of inert materials from site.

Before the introduction of the landfill levy most construction site waste materials including bricks and concrete was bulked up and transferred to a landfill site for disposal. No consideration was given to recycling. There are now stringent limitations across the sector, in conjunction with an increase in environmental focus, and also the commercial benefits in ensuring that this kind of waste is recycled. Addititionally there is greater recognition of the large choice of potential business opportunities to use recycled aggregates in the construction process on future 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 probably be transformed into a recycled concrete aggregate.

To recycle concrete aggregate to a high standard and resalable product, it has to be totally free from 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 task of recycling the concrete can typically be achieved in one of two ways. Some demolition companies will install a crushing device on the demolition site, whereas a lot of contractors will choose to move the waste to be recycled, back to their own 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 position a crushing unit on site to avoid incurring extra transport costs in taking the materials to a sorting and crushing centre.

There are lots of legal and environmental issues which midlands demolition contractors have to now follow when undertaking their projects.

The Growing Need for Top Quality Recycled Aggregate

Before starting the crushing procedure, it needs to be determined what the end product will be used for to make sure that the recycled aggregate is to meet the required standards. There’s huge demand for recycled aggregate to be used within the construction process. As a product, recycled concrete aggregate can be used for nearly every 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 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 bits of recycled aggregate may be suited to 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 increasing. There are key standards in place that are focused upon improving the recycled concrete aggregate sector. Through research and development, more widespread uses are now being identified 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 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. As well as 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 good quality grades the 20-5mm recycled aggregate can be utilised as an aggregate base in road construction and the quality meets the standards required to allow its reuse in concrete production.

On the list of important requirements when using recycled aggregate is choosing the best specification for the task. For example, when using 20-5mm coarse graded aggregate as a highway base, the thickness of the layer needed will have 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 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 laid, suitable layers of asphalt or concrete can be laid over it to create the road surface.

Recently, in the UK we appear to have more rain than hot sunshine and as a consequence the selected aggregate must have the capacity to withstand variances in temperatures and conditions e.g. dampness for very 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, plus for use in ready mixed and precast concrete products. With its drainage qualities, 20-5mm recycled aggregate is a useful product.

The build programme for London’s Olympic Village, has specified the use of a clean recycled concrete aggregate crushed to a 20-5mm specification.

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 recognized a significant opportunity to boost awareness of climate change and the challenges that surround it, and bring it to the Globe’s notice. With the eyes of the Entire world observing, the Olympic Games give an exceptional opportunity to communicate key messages concerning sustainability. During the whole development of the Olympic project, there exists a commitment to make 2012 the most sustainable Olympic Games ever held. This focus originated when planning the development and build programmes for the amenities and venues, the transportation links and system, the hosting of the Games themselves and will end by leaving a long lasting legacy of a sustainable environment.

Since London was awarded the Games, all suppliers involved with the development specifications, from the building of the Olympic Stadium, the Olympic Village and transportation links between the venues have been encouraged upon ensuring the use wherever possible of sustainable resources. Throughout the entire Olympic build programme architects have worked hard to locate appropriate sustainable materials for use in the build programme. At the conclusion of the whole project there will be some clearly obvious examples 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. Some of those products which visitors to the games and its countless venues will not even think about how recycled aggregates are employed as part of the overall construction project. However developers and specifiers of resources for use in the build programme will be secure in the knowledge that they have selected sustainable products which include, the most suitable recycled concrete aggregates as part of the project. With its recognized characteristics, let us hope that somewhere in the world wide Television 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.

Summary

How times have developed in recent years for the demolition and construction industry. Companies have had to change to meet tough green standards. As with nearly every segment, new laws and legislation dictate the criteria to which your company must aspire, if it is to achieve success.

Businesses engaged in the manufacturing of recycled concrete 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 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 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 to be used in highway construction and driveways.

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