RSTA News
Budgetary cutbacks, sustainability issues and meeting the expectations of motorists is a challenging combination that is seeing local highway authorities turn to the road surface industry for cost effective and innovative solutions reports Howard Robinson, chief executive of the Road Surface Treatments Association. The road surface treatments sector believes that it has a positive role to play by working with clients to develop solutions that are innovative, cost effective and sustainable. Accordingly, it is investing in new products and processes and is ready to collaborate and share best practice in order to provide ‘more for less’ and ‘less is more’ in terms of meeting budget restrictions and delivering carbon emission reductions. A series of pilot tests currently being carried out by the Carbon Trust exemplify the sector’s readiness to collaborate and innovate. The pilots are examining how to reduce the heat needed to mix asphalt – currently 170o C is required. Cooler asphalt will significantly reduce the energy needed to produce it and as it will harden faster, could cut the time taken for road works by up to 12 hours. The tests will examine heat recovery technology to reduce the carbon emissions from the burner that heats and then dries the aggregates. This is the main energy consumer in the hot asphalt manufacturing process. A further benefit of using cooler asphalt is the reduction of many health and safety risks associated with using higher temperature materials. The pilots are being carried out by leading road surfacing companies including RSTA members Aggregate Industries and Nynas Bitumen. As part of the pilots, Aggregate Industries are to install an innovative heat recovery system at its Haughmond Hill site in Shrewsbury. This will cut energy use by using waste heat to pre-heat the air combusted in the asphalt burner. By 2020, this system could be used to save 33,000 tonnes of carbon every year. Nynas is working with a consortium including Tarmac, Atkins and MIRO to provide demonstration projects of semi-warm and cold asphalts. A further consortium comprising United Asphalt, Shell Bitumen and Berkshire Engineering will examine how to maximise the amount of reclaimed asphalt which can be used in road resurfacing by combining warm mix asphalt and a new aggregate dryer. The Carbon Trust believes that the pilots could point the way to reducing 339,000 tonnes of carbon off the industry’s annual carbon footprint by 2020. That is the equivalent of a 39 percent reduction.
Throughout the UK, local road authorities are working with road surface treatment companies with the aim of getting ‘more for less’. In the South West, the Dorset Works Organisation, the contracting division of the County Council, is working with Velocity UK Ltd and trialling a new pothole patching process that promises the holy grail of fast, cost effective and sustainable road maintenance. The process removes the conventional need to “dig-out” thereby producing minimal waste and saving landfill costs. Mixed bitumen and aggregate is blown into the pothole at high velocity, is applied directly and the area is sealed to prevent further damage. The process is also successfully used by Bournemouth Borough Council who are also reporting good results with an infrared patch repair system, developed by Nuphalt Ltd, whereby the road surface is heated to 180oC, the asphalt is then ready for recycling and is mixed with a small amount of fresh material to fill depressions. The system has been used in the United States since 1983. It recycles all materials in-situ, the patch repair lasts longer and there is minimal damage to the adjacent road surface. In Woking and Durham a more vegetarian approach is being taken with the use of a new vegetable-based binder as a natural alternative to bitumen or petroleum resin-based binders. Available from Colas, the Vegecol binder lowers the temperature at which asphalt material is mixed by as much as 40 degrees which results in reduced production plant fuel consumption and fume emissions. Furthermore, because surfacing materials using Vegecol contain no hydrocarbons from refining oil, the finished product does not degrade when it comes into contact with fuel spillages. Colas uses an emulsified version of Vegecol as the binder in its Fibredec process – a surfacing system with high tensile strength consisting of glass fibres laminated between two layers of binder. The process was specified by Sustrans, the sustainable transport charity, to resurface a cycle way in Woking and it has been used in Durham to resurface a major pedestrian thoroughfare in the city. Used throughout Germany, Hungary, Belgium and on the Caribbean island of Martinique, Colas believes that as an alternative to oil-based products, Vegecol has a definite future in the UK. The road surface treatment industry is also developing new plant production and finishing processes. Pavement retexturing specialist, Klaruw, has recently trialled a prototype machine for ‘wet application’ shot blasting, designed to improve the macro-texture and micro-texture of pavements to restore skid resistance levels. The Macrotex (MAT) plant offers advantages in process control, treatment flexibility and coverage rate compared with conventional shot-blasting machines. Most significantly, it allows retexturing to be carried out in wet weather, even in heavy rain. Primarily developed to improve the macro-texture – the texture depth that allows surface water to escape to prevent aqua-planing - of most natural aggregate surfaces, the process also improves the micro-texture – the surface friction that provides wet weather skid resistance. By reworking existing surfaces, the MAT plant extends the service life of structurally sound roads by several years, it applies no new material, produces minimal waste and recycles the water and shot used in the process thereby providing a highly sustainable solution for local road authorities tasked with providing safe road surfaces whilst reducing their carbon footprint under the Climate Change Act 2008 and requirements under the National Indicator 185 (NI 185) ‘Percentage CO2 reduction from LA Operations’. Trials of MAT have been undertaken by Area 10 Managing Agent Contractor A-one+ on sections of concrete, hot rolled asphalt and thin surfacing on the M56 near Chester. The North Wales Trunk Road Agency is also examining results following trials on hot rolled asphalt and thin surfacing on the A55 North Wales Coast Road. Depending on pavement type and condition, the machine can treat 1300 to 3000sq/m of pavement per hour – equivalent to 3 – 7 km a day. The plant could be much in demand as road authorities face cuts in maintenance budgets while road safety performance targets remain high. These are challenging times. Despite the widely predicted cuts in highway authority budgets, safety and performance standards and sustainability targets must still be met. The road surface treatments sector is playing an increasing role in providing the solutions that enable highway authorities achieve more for less.
