Introduction

Mention the phrase demolition to almost anyone and the scene that instantly comes to mind is usually a vision of a building being blown up and collapsing to the ground. A lot of people have stated they would really like to push the button, to trigger the explosive units that bring a disused building to the ground. In many cases what comes down, must go up and we are witnessing many dilapidated properties being razed making way for future development, frequently within a regeneration project.

For companies who over many years have developed their business surrounding the demolition of architectural structures, the demolition sector is now much more reaching than simply demolishing outdated buildings. As soon as the property is demolished the massive task of site clearance starts and in a community where consideration of the environmental impacts are ever increasing on most peoples agenda, the material remains from demolition must be sorted for recycling purposes. This can 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 completely ready for reuse in the construction of new highways or buildings. Increasingly though, via advancements in technological development, residues such as rubble to be recycled have to meet an extremely high standard for reuse in construction projects.

When crushed, the assorted sizes of recycled aggregate will govern the likely usage potential of the product. Large sizes might be used as ornamental 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 highway construction. With an increasing amount of possibilities recognized for the reuse of recycled aggregate, the whole demolition and construction market is generating a substantial contribution to sustainable development. Following demolition of a site, many demolition contractors have expanded their service offering to include site clearance services.

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

In 1996, UK Government added a levy on all waste materials going to landfill. The duty is paid in addition to standard gate rates for waste material being disposed in landfill and since its introduction the price has increased on an annual basis. When it was first introduced, the standard level of duty for general wastes going to landfill was �7 per tonne and �2 per tonne for inert materials. The levy was created to persuade commercial and industrial businesses and local authorities collecting from properties, to divert waste away from landfill for recycling. In April 2009, the common rate of landfill tax rose to �40 per tonne and it is scheduled to increase each year by �8 per tonne until 2013. The reduced level of duty charged upon any inert materials going to landfill such as concrete and soils, has stayed relatively stable in recent years and is currently at �2.50 per tonne.

Nonetheless, the weight of a bulk load of these inert products going direct to landfill will guarantee that the entire cost of disposal becomes extremely expensive and so even in the demolition and construction market, 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.

New development projects often start out with the decision to bring in controlled demolition machinery contractors to demolish a building first.

Next time you see a demolition project happening or go past any construction site during a build programme, it is obvious to see the amount of waste materials being created. If waste material is not in skips, piles of rubble will probably be stacked high. The placing of concrete waste in skips has been a significant problem for waste companies for several years. Having been an employee in the waste industry, I’ve seen skip lorries tipped backwards with the cab of the vehicle up in the air, a result of the sheer overloading of waste skips with building site waste.

Each and every year, the uk produces around 330 million tonnes of waste and approximately 90 million tonnes of this is coming from building and demolition wastes. This figure has remained reasonably constant since 2001. Around two thirds of this waste is generally recycled or reused in land reclamation or agricultural improvement projects. Since the late 1990s there has been a steady rise in the quantities of construction waste being recycled and this has been helped by developments in technology that have led to improved crushing technology to create more frequent use of different specifications of recycled aggregates.

In the past few years, the construction industry as a whole has worked hard to encourage construction project managers to put a greater focus upon recycling on site. This has led to a rise in the recycling of inert materials from site.

Prior to the introduction of the landfill levy almost all construction site waste including bricks and concrete was bulked up and taken to a landfill site for disposal. No deliberation was given to recycling. These day there are strict limitations across the sector, coupled with an increase in environmental awareness, and also the commercial advantages in making sure that this kind of waste is now recycled. Addititionally there is increased recognition of the wide array of opportunities to re-use recycled aggregates in the construction process on future construction projects or in fields such as landscaping or home and garden DIY. Following the demolition process, together the waste concrete, bricks, masonry etc will 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 has to be completely free of other debris such as wood, paper, card, steel and other general waste materials. The end product must conform to the specifications of British Standard BS 8500. The task of recycling the concrete can usually be achieved in one of two ways. Some demolition companies will install a crushing system on the demolition site, whereas a lot of contractors will prefer to carry the waste to be recycled, back to their own premises for segregation 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 position a crushing appliance on site to avoid incurring extra transportation costs in taking the materials back to a sorting and crushing facility. There is now very advanced crushing equipment on the market to reduce concrete to a very fine specification.

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The Increasing Need for Top Quality Recycled Aggregate

Before commencing the crushing process, it must be determined what the end product is to be used for to make certain that the recycled aggregate is to satisfy the necessary standards. There’s huge requirement for recycled concrete aggregate to be used within the construction process. As a product, recycled aggregate can be used for almost any type of concrete structural function, road surfacing or pipe laying project. Having passed through the crusher the pieces of aggregate can be separated by size. Bigger pieces can be retained as a cosmetic product to be used in garden rockery projects, or they might be passed back through the crusher to be crushed to a reduced size. The smaller sized bits of recycled aggregate might 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 top 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 growing. There are key standards in place that are targeted upon improving the recycled aggregate market. By means of research and development, 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 a wide range of different 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 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 commencing. In achieving such high 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.

One of several important requirements when using recycled aggregate is choosing the right specification for your task. By way of example, when making use of 20-5mm coarse graded aggregate for a road base, the thickness of the layer demanded will have to be determined to stand up to 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 commonly employed as a road base is that it helps good drainage. Once the recycled aggregate is installed, appropriate layers of asphalt or concrete can be laid across it to build the road surface.

In recent years, in the United Kingdom we seem to have more rain than sunshine and as a consequence the selected aggregate must have the capacity to endure variances in temperature 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 is the appropriate 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 flexible product.

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 identified a major opportunity to boost awareness of climate change and the problems which encircle it, and bring it to the World’s notice. With the eyes of the Entire world observing, the Olympics provide an exceptional chance to convey key points about sustainability. Through the whole growth and development of the Olympics project, there is a determination to make 2012 by far the most sustainable Olympics ever held. This focus began when planning 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 behind a long lasting legacy of a sustainable healthy environment.

Since London was awarded the Games, all suppliers involved with the development specifications, from the design of the Olympic Stadium, the Olympic Village and transport links to the venues have been focused upon ensuring the use wherever possible of sustainable materials. Across the entire Olympic build programme architects have worked hard to discover acceptable sustainable materials for use in the build programme. By the end of the overall project we will see some clearly obvious examples 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 sites will not even think about how recycled aggregates are used as part of the overall construction project. However developers and specifiers of materials for use within the build programme will be comfortable in the knowledge that they have selected sustainable products which include, the most appropriate recycled concrete aggregates as part of the project. With its recognized 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 changed in recent years in the demolition and construction business. Companies have needed to adapt to meet tough green conditions. As with virtually any segment, new regulations and legislation determine the criteria to which your company must aspire, if it is to achieve success.

Firms engaged in the generation 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 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 road construction and driveways.

Tags: recycled aggregates, regeneration project