Asphalt Review - Volume 29 Number 2 (June / July 2010)

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ASPHALT REVIEW ...continued from previous page • mix design method; • design void content; • test results for design (laboratory mix); • test results for production mix; • field trial details; and • performance monitoring. Data Exchange Validation Projects should be undertaken jointly by industry and the road authorities. Any reports produced should therefore be provided to all participants for review. This will ensure that they are accurate and, where appropriate, do not divulge details of any proprietary products. The reports provided may then be used by road authorities, in consultation with industry, as a basis for consistent and appropriate specifications. Warm-mix asphalt position statement by GAPA The Global Asphalt Pavement Alliance (GAPA) is comprised of multi-national and national asphalt pavement associations throughout the world. We recognise the asphalt industry as the ultimate steward of our own product in terms of quality, performance, safety, and environmental benefit. In an effort to improve its already excellent environmental performance record, the GAPA supports the development and implementation of warm-mix asphalt. Warm-mix asphalt is the term used to describe a class of technologies employed to reduce the production and paving temperature of asphalt mixtures by 10 to 40 degrees centigrade. This temperature reduction may be effected through the use of mineral or organic additives or by mechanical means to introduce foaming into the production of asphalt mixtures. Warm-mix asphalt has been recognised as an environmentally friendly method to produce asphalt mixtures with the following benefits: • Higher product quality through better consistency and improved compaction; • Sustainability through reduced energy consumption and better performance; • Improved air quality through reduced emissions; • Reduced climate impact through reduced greenhouse gas generation; • Economic advantage through an extended paving season and longer haul distances; • Improved working conditions through the reduction of fumes and the reduction of temperature. The effectiveness of this green technology has been proven through ongoing implementation in Europe and the United States. This will inevitably become the standard practice for asphalt mixture production. We encourage others within the industry as well as our agency partners in all countries to become informed about warm-mix asphalt technology and to begin a path toward its implementation. Australian Asphalt Pavement Association European Asphalt Pavement Association Japan Road Contractors Association National Asphalt Pavement Association, USA Southern African Bitumen Association GAPA widens membership two years after formation At this time two years ago, the Global Asphalt Pavement Alliance (GAPA) came into being. The agreement to establish the alliance was signed in Copenhagen on 21 May 2008 and reported in the June-July issue of Roads. The signatories to the alliance were: Australian Asphalt Pavement Association (AAPA); European Asphalt Pavement Association (EAPA); Japanese Road Contractors Association (JASA); (US) National Asphalt Pavement Association (NAPA) Southern African Bitumen Association (SABITA). The purpose of the Alliance was to build on existing links between the world asphalt associations to exchange information relevant to our industries. It recognised that there are many current and emerging issues such as sustainability and new technologies associated with pavement designs and materials. Most of these are relevant across the world and sharing information will be of benefit to all GAPA members. Under GAPA, the pavement associations can also provide consistent information to road authorities and the world community. This lead to a statement from the GAPA meeting held in January 2010 highlighting the importance of warm mix asphalt. In recent times, a lot of the information from research being undertaken in the US has been provided to AAPA and the other members. Information from Europe has also been provided, including on the use of asphalt in railway tracks that is highlighted in this edition of Roads. Recognising the benefits of the global alliance, two more asphalt associations have recently joined GAPA. They are Roading New Zealand and the Mexican Asphalt Association [Asociación Mexicana del Asfalto, A.C. - (AMAAC)]. Other Associations are expected to join over the next few months. Currently Mike Acott, President of NAPA is the Executive Officer of GAPA. 24 ROADS JUNE 2010/JULY 2010
Beyond Warm Mix Asphalt Several new technologies have been developed that reduce energy usage for asphalt manufacture with a consequent lowering of production and placement temperatures. These materials are called “warm mix asphalt”, or WMA and the major Validation trial of these technologies is decribed in page 18 of this edition of Asphalt Review. However, trials are also being conducted in New Zealand into asphalt mixes that can be produced at even lower temperatures. These are referred to as half-warm asphalt. The following paper, prepared by Dr Bryan Pidwerbesky - Fulton Hogan, Alan Beuzenberg - Christchurch City Council, and John De Bono - Christchurch International Airport, reports on the reasons for using warm and half-warm mixes, including operational and technical benefits, reduction in greenhouse gas emissions and improvements to worker safety. The paper was delivered at AAPA’s 13th International Flexible Pavements Conference in November 2009 at Surfers Paradise in Queensland. (Condensed version - full version available from Conference papers 2009 - aapa@asn,com.au) 1. Introduction Climate change and the increased awareness of greenhouse gas emissions focusses industry and the community’s attention on the combustion of fossel fuels. Therefore although bitumen is not consumed in the production of flexible pavements, infact remains 100% recyclable”, the industry does recognise that it must constantly look at technologies to even further reduce the energy concumed in producing asphalt materials. The industry also recognises the cost saving associated with lower fuel consumption. Recognising this, Fulton Hogan in New Zealand has identified an advanced Half Warm asphalt technology and has obtained a licence for its use. 2. Background to Warm Mix Asphalts The drive to reduce greenhouse gas emissions from hot-mix asphalt production by reducing fuel usage is not new. A number and variety of manufacturing techniques that reduce the energy used to manufacture asphalts have been developed beginning in the 1990s. They are generally classified into two categories: - Additive based systems, where a proprietary additive is used to allow a reduction in energy usage; and - Alternative manufacturing techniques such as foaming. Some processes use a combination of both techniques, i.e. a proprietary additive in conjunction with modified manufacturing processes. Warm Mix asphalt offers a significant reduction in production temperature of up to 40 C and a reduction in greenhouse emissions associated with the production of in the order of 20%. 3. Half-Warm Mixes In 2006, Fulton Hogan identified a new process that would use even less fuel for producing asphalt mixes. This process, developed in Europe, but licensed worldwide, combines the use of an additive with plant and process modifications, resulting in asphalt produced below 100°C, and able to be placed at temperatures as low as 60°C. This new process was radically different to the Warm-Mix asphalts previously considered. It involved a patented system, using proprietary chemical additives with a change to the asphalt production process. While the process change requires modification to asphalt plants, the degree of modification is substantially less than alternative processes and is hence more ASPHALT REVIEW A warm mix asphalt produces almost zero fumes and is safer to handle economically viable. Because the asphalt mix is produced at temperatures below 100°C, energy demands are significantly reduced. Experience in Europe demonstrated that burner fuel savings in the order of 50% are achievable. Because this new process differs so significantly from previous Warm- Mix asphalts, a new term was coined to describe the material: “Half-Warm Mix Asphalt”. This term highlights the substantial reduction in production temperature of at least 70°C compared with similar hot-mix asphalts, and 30° C cooler than Warm-Mixes. The significant reduction in burner fuel usage reduces greenhouse gas emissions by as much as 50%. In addition, the cooler asphalt does not emit the “blue smoke” fumes from production and handling. Field crew also benefit from the Half- Warm asphalt process as the lack of blue smoke emissions reduces worker exposure to fumes, and the lowered placement temperatures virtually remove the risk of serious burns. Economically, the costs of the additive and plant modifications offset the savings in fuel usage. At the moment the process is borderline economic, but as fuel costs continue to rise, the use of the Half-Warm process will reduce the effect on the price of asphalt. Substantial quantities of Half-Warm asphalt pavements have been constructed in Europe and the United States. Much ROADS JUNE 2010/JULY 2010 25
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Page 3 and 4: Chairman’s report ASPHALT REVIEW
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Page 8 and 9: ASPHALT REVIEW AAPA/Austroads Warm
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Page 14 and 15: ASPHALT REVIEW southern hemisphere;
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Page 19 and 20: The Road to Innovation Ever increas
Page 21 and 22: Fulton Hogan and PRS Join Together
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Asphalt Review - Volume 29 Number 2 (June / July 2010)

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