ICE - Institution of Civil Engineers - Virtual Library

In line with the UK Government's sustainability initiatives, finding new uses for discarded materials is an important issue which is attracting increasing attention. One such material is glass, which can have various applications once recycled. London Remade, the capital' recyclables market development agency, is currently investigating markets for recycled glass, including glass sand that can be used as replacement for quarried material.

This is a review of a report produced by the Transport Research Laboratory (TRL) as part of an industry and research consortium led by Tarmac, with funding from the Waste Resources Acton Programme (WRAP) and the Department of Trade and Industry. The work looked at the potential use of recycled rubber crumb from used tyres and waste plastic as aggregates in asphalt and concrete and included product development trials.

The increased demand for materials for flood and coastal defences as sea levels rise and rainfall increases should be reflected by a sustainable use of natural resources. Recycled and secondary materials offer significant potential to reduce the demand for primary materials, but the way in which this is done in a sensitive water environment will be of interest to the whole of the construction industry. The paper examines five criteria that should influence choices between materials options for projects: whole-life costs, technical efficacy, impact on the local environment, environmental impact of materials production and procurement policy. The latter is examined in the context of the sensitivity of the procurement of tropical hardwoods, which are in particular demand because of their durability. A case example is given of the reconstruction of the fire-damaged Southend Pier in which reclaimed tropical hardwoods were imported from the Netherlands for most of the work. Finally, two examples of the reuse of tyres in baled form are examined. One example looks at the technical advantages of using these recycled materials in a flood embankment project and the other at a pilot project to examine and try to allay concerns about leachates from the tyre material.

The theme of this special issue, the reuse of materials, can apply to: (a) the recycling of marine sediments from areas of natural deposition to replenish denuded frontages elsewhere; or (b) the alternative uses of otherwise waste material derived from navigation dredging activities. Such material reuse in the marine environment can provide environmental benefits, assist in reducing risks from tidal flooding or coastal erosion if used in foreshore recharge schemes, or cost-effectively provide construction resources. This paper considers drivers behind reuse of materials in the marine environment, identifies the opportunities and constraints to its application, and discusses key sustainability aspects of these approaches, such as economic, social and environmental issues. Example case studies are provided of two alternative use schemes and one sediment recycling scheme, highlighting both the practical benefits and the practical complexities of these approaches, depending on the specific situations in which they are set.

To attain economically viable and environmentally friendly tyre recycling, it is necessary to develop new applications and products, which will use tyre by-products (especially the steel cord) as raw materials. The authors demonstrate that the steel fibres recovered from used tyres can be used to reinforce concrete elements. This application has a great potential, as it is estimated that more than 500000 t of high-quality steel fibres could be recovered annually from used tyres in the EU alone. This paper presents the work carried out as part of various ongoing projects on the use of steel fibres in concrete construction. The first part of the paper deals with waste management issues, the methods used to recover steel fibres from tyres, and existing applications of used tyres. The second part presents the mechanical behaviour of concrete elements reinforced with these steel fibres and discusses the relevant design and economic issues. It is concluded that the use of these steel fibres in concrete construction will benefit not only the construction industry, but also the producers and recyclers of used tyres.

A study is being undertaken at the University of Liverpool to investigate the potential for using construction and demolition waste (C&DW)-derived aggregate in the manufacture of precast concrete building blocks. Recycled aggregates can be used to replace quarried limestone aggregate, usually used in coarse (6 mm) and fine (4 mm-to-dust) gradings. Market research has been carried out to determine the economic viability of using C&DW-derived aggregates in blocks. The availability and transportation costs of quarried and C&DW-derived aggregates have been compared and there appears to be scope for investigating the technical as well as the economic aspects of the use of C&DW-derived aggregates in block manufacture.

Large volumes of wastes are associated with the production of aggregates and dimension stone. Fine-grained wastes are particularly problematic and are deposited in settlement ponds or managed by stockpiling until backfill space becomes available. Although these fine materials have poor engineering properties, when they are mixed with hydraulic binders in a CO₂-rich atmosphere, they can be bound together to form pellets suitable for use as aggregates. In the present work, a by-product called hassock, which originates from the quarrying of Kentish ragstone, is investigated for use as secondary aggregate. In excess of 200000 t of this poor-quality fine-grained material, originating from the Lower Greensand Formation of southern England, are disposed of each year. Hassock waste was blended with other solid waste products, namely cement kiln dust, ground granulated blast furnace slag and pulverised fuel ash, and was pelletised in a CO₂-rich atmosphere. The pellets, produced by carbonate cementation; typically have a pH of 9–9·5 and aggregate impact values ranging from 14 to 19.

The paper assesses the current brick recycling industry in the UK, and highlights the low rate of brick recycling that is currently achieved. The benefits of increased brick recycling are identified, but it is noted that in order for this to be achieved improved technology to allow more efficient recovery of bricks would be necessary.

Making use of recycled and reused building materials and products in the building industry is well understood as an effective way of reducing the environmental impacts associated with materials. To facilitate the recycling of materials, buildings should be designed as recyclable buildings—buildings that enable the dismantling and the reuse or recycling of building elements and materials. However, currently buildings are seldom designed in this way. Environmental benefits have proved insufficient to encourage the production of recyclable buildings, and other benefits, in particular economic and social benefits, appear to be key in increasing the production of such buildings. This paper reports on a study of the social and economic benefits of recyclable buildings. The study investigates current building materials and components and their ability to be dismantled and reused or recycled. A questionnaire and interviews with building designers were used to investigate the potential and the barriers to the use of recyclable materials and components as well as identifying methods to overcome the barriers and promote the technology. The paper considers how legislation and the provision of information can act as drivers for change and also suggests that to maximise the environmental benefits, buildings should in fact be designed to create a closed-loop material cycle. It concludes by pointing to a few new examples of buildings designed for reuse and recycling, which may suggest a move towards recyclable building in the construction industry.

The Eden Project aims to promote the understanding and responsible management of the vital relationship between plants, people and resources, leading to a sustainable future for all. Located in a former china clay pit, the project has welcomed over five million visitors since opening in 2001 and is home to the two largest conservatories in the world. During the early phases of development the Eden Project recognised that its approach to waste was not wholly consistent with its sustainability ambitions and a waste neutral strategy was developed. A new phase of development is now being undertaken and the Waste Neutral Strategy is central to the procurement process. This paper presents a case study of waste minimisation and material reuse at the Eden Project, including the management of construction waste, setting out the experience of the Eden Project and McAlpine Joint Venture, the contractor for the design-and-build contracts under which all phases of development have been procured.