Recycling of transport infrastructure waste could be a huge industry

Recycling of waste from transport infrastructure, such as road asphalt, could be a huge industry, said delegates at a transport recycling conference. However, the Government’s waste management licensing scheme is too inflexible, and actually inhibits recycling within the transport infrastructure sector, according to a new report launched at the conference.

Other recommendations for the Government contained in Recycling in Transport Infrastructure, published by the Transport Research Laboratory (TRL), includes the need to develop clearer guidance on the definition of waste, and to produce accurate data on aggregates waste and recycling. One example of a material that has been wrongly defined as waste by the Government is soil. “Topsoil is a resource, not a waste,” said George Flemming, Professor of Civil Engineering at the University of Strathclyde, and Fellow of the Transport Research Foundation, at the launch of the report on 8 October. The report also calls for an extension of the Waste Resources Action Programme (WRAP) to encourage recycling in transport infrastructure and other aspects of the construction industry.

The report also contains recommendations to all stakeholders in the sector. Advice to local authorities include the suggestion that they should improve their liaison with industry and increase training and awareness raising in order to improve the environmental performance of the industry. The operators and owners of infrastructure need to develop performance-based specifications to ensure that recycled materials are ‘fit for purpose’.

Advice is also given to contractors, who need to encourage suppliers to adopt robust quality control systems for their products, and should liase with environmental regulators as early as possible in the life of a project in order to assess the position regarding alternative materials and the requirements for waste management licences or exemptions. Finally, recommendations to the research community include the need to adapt to changing customer requirements, which will increasingly involve working with industry and infrastructure owners to identify problems and ways of solving them, rather than depending on direct government funding.

Case studies in the report include the VEB hot asphalt recycler which is used for repaving pavements in Leicestershire. The asphalt recycling machine is mounted on the back of a lorry, which can then be sited where work is being carried out. Old material is removed from the pavement and fed into the machine, heated to 190°C, and mixed with additional bitumen to make up for that lost through oxidation. Fumes are also drawn back into the burner and reheated to reduce emissions.

Leicestershire County Council reports that the machine produces a reasonably consistent material, and as each section of pavement is dug up and then replaced almost straight away, there have been no complaints from local residents unable to use foot paths. The machine is able to achieve around 15 batches per day, producing up to 22 tonnes of recycled bituminous material, with each load taking between 15 and 20 minutes.

Other case studies include a British Airports Authority (BAA) team involved in the construction and renewal of airfield pavements; Burntwood bypass in Staffordshire which has included the use of incinerator bottom ash; and the supply, recycling and reuse of railway track materials by Railtrack.

Waste minimisation is also important, said Peter Guthrie, Professor of Engineering for Sustainable Development at the University of Cambridge. “It is, I think, one of the most important issues in the construction industry,” he said. In 1999, 72.5 million tonnes of waste were produced by the sector, he said, although, in reality, he believes that it is not known how much is being produced. However, there has been significant progress since the 1990s, although 94% of material that is recycled is still only being utilized for low grade uses. “It’s not clear what the incentives are to move recovered material up the hierarchy,” said Guthrie, emphasising that he would like to see recycled material being used for higher grade applications.

Guthrie also called for legislation to prevent the demolition of one building only for it to be replaced by an almost identical construction. “Have we allowed financial accounting to take over from engineering decisions?” he asked.

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