Introduction

Mention the phrase demolition to almost any person and the picture that instantly comes up is a vision of a structure being blown up and collapsing to the ground. Many people have claimed that they would really like to push the button, to detonate the explosive units which bring a disused property to the ground. In many cases what comes down, must go up so we are seeing many dilapidated properties being razed to make way for potential future development, frequently together with a regeneration project.

For businesses that over many years have established their business surrounding the demolition of architectural structures, the demolition sector has become far more reaching than simply blowing up outdated buildings. Once the structure is demolished the huge task of site clearance begins and in a world where consideration of the environmental effects are high on many peoples agenda, the material remains coming from demolition must be sorted for recycling reasons. This tends to include such materials as steel, wood, plastic, brickwork and concrete.

The vast majority of the materials are bulked up and transported to appropriate recycling plants for reprocessing. Resources such as bricks and concrete are usually crushed and become a recycled concrete aggregate product ready for reuse in the construction of new roads or buildings. Ever more though, by means of advancements in technological development, derivatives such as rubble to be recycled need to meet a very high standard for reuse in construction projects.

When crushed, the varied grades of recycled aggregate will govern the future usage potential of the product. Larger sizes could be used as ornamental rockery products in landscaping whilst much finer, shingle like product can be utilised to provide a bedding for pipe laying or for a layer in street construction. Through an increasing number of options identified for the reuse of recycled aggregate, the entire demolition and construction industry is building a substantial contribution to sustainable development.

Reasons Behind 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 levy is paid out in addition to standard gate charges for waste material being disposed in landfill and since its initial release the cost has increased on an annual basis. When first introduced, the common rate of tax for general wastes going to landfill was �7 per tonne and �2 per tonne for inert substances. The tax was created to motivate commercial and industrial businesses and local authorities collecting from properties, to divert waste away from landfill for recycling. In April 2009, the typical rate of landfill tax rose to �40 per tonne and is also timetabled to increase each year by �8 per tonne until 2013. The reduced rate of tax charged upon any inert materials going to landfill such as concrete and soils, has stayed comparatively stable in recent years and is presently at �2.50 per tonne.

Nevertheless, the weight of a bulk load of those inert products going straight to landfill will ensure that the entire 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 making use of demolition equipment is often changed into a variety of reusable products for use in other construction projects.

Next time you see a demolition project happening or go past just about any construction site during a build programme, it is very clear to see the quantity of waste materials being created. If waste isn’t in skips, heaps of rubble will probably be stacked high. The placing of concrete waste materials in skips has been a major issue for waste companies for many years. I have worked in 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 building site waste.

Each year, the united kingdom produces around 330 million tonnes of waste material and it is estimated that around 90 million tonnes of this is from building and demolition wastes. This number has remained relatively constant since 2001. Around two thirds of this waste is normally recycled or reused in land reclamation or agricultural improvement projects. Since the later part of the 1990s there’s been a gradual rise in the quantities of construction waste materials being recycled and this has been assisted by advances in technology which have led to improved crushing products to make more widespread use of different grades of recycled aggregates.

In recent years, the construction sector in general has worked hard to encourage construction project supervisors to place a greater focus upon recycling on site. This has led to a growth in the recycling of all inert materials from site.

Prior to the introduction of the landfill levy all construction site waste including bricks and concrete was bulked up and transported to a landfill site for disposal. No deliberation was given to recycling. There are now stringent restrictions across the sector, as well as an increase in environmental focus, and also the commercial advantages in making certain that this sort of waste is now recycled. Addititionally there is increased recognition of the vast array of opportunities to re-use recycled aggregates within the construction process on new 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 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 must be entirely free of other contaminants such as wood, paper, card, steel and other general waste materials. The final product must also conform to the specifications of British Standard BS 8500. The process of recycling the concrete can normally be achieved in one of two ways. Some demolition companies will transport a crushing device on the demolition site, whereas various contractors will choose to move the waste to be recycled, to their premises for sorting for recycling or re-use. On projects where demolition and new construction is to take place at the same site, the contractor is likely to locate a crushing appliance on site to escape incurring additional transport costs in taking the material to a sorting and crushing facility. There is now very sophisticated crushing equipment available to reduce concrete to a very fine specification.

Many recognized Nottingham demolition contractors extended their services to include site clearance services.

The Increasing 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 ensure that the recycled aggregate is to match the necessary standards. There’s huge demand for recycled concrete aggregate to be used within the construction process. As a product, recycled concrete aggregate can be used for virtually 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 may 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 smaller size. The smaller sized pieces 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 interest in good quality crushed aggregate is ever-increasing. There are key standards in place that are focused upon improving the recycled aggregate industry. By means of research and improvement, more widespread applications are being discovered for the employment 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 chunks 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 footing material prior to construction projects commencing. In achieving such top quality grades the 20-5mm recycled aggregate can be used as an aggregate base in road construction and the quality meets the specifications required to allow its reuse in concrete production.

On the list of important criteria when using recycled aggregate is selecting the correct specification for the task. For instance, when using 20-5mm coarse graded aggregate for a road base, the thickness of the layer demanded must be determined to tolerate 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 supports good drainage. Once the recycled aggregate is laid, appropriate layers of asphalt or concrete can be laid above it to build the road surface.

Recently, in the UK we appear to have more rain than sunshine and therefore the chosen aggregate must have the ability to tolerate variances in temperature and conditions e.g. dampness for very long periods, torrential downpours, long dry spells. With its good drainage characteristics, the recycled 20-5mm product is 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 useful product.

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 focal point of its bid. The bid team identified a major opportunity to increase awareness of climate change and the issues that encircle it, and bring it to the World’s attention. With the eyes of the World watching, the Olympic Games give an exceptional chance to communicate key messages about sustainability. During the entire development of the Olympic project, there exists a commitment to make 2012 by far the most sustainable Olympics ever held. This focus began when setting up the design 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 heritage of a sustainable healthy environment.

Since London was granted the Games, all suppliers associated with the development requirements, from the building of the Olympic Stadium, the Olympic Village and transport links to the venues have been encouraged upon guaranteeing the use wherever possible of sustainable materials. Across the entire Olympic build programme construction managers have worked hard to identify practical sustainable materials for use in the build programme. By the end of the overall project there will be some clearly obvious cases 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. Some of those products which visitors to the games and its many locations won’t even consider how recycled aggregates are already specified as part of the overall construction project. However developers and specifiers of materials for use in the build programme will be comfortable in the knowledge that they have selected sustainable products including, the most suitable 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. 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 recently for the demolition and construction industry. Organisations have needed to change to meet demanding green specifications. As with nearly every industry, new regulations and legislation determine the criteria to which your company must aspire, if it is to achieve success.

Firms involved in the production of recycled concrete 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 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 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.