Physicochemical Characterisation of Bituminous Bound Composite Paving Materials

Lead Research Organisation: University of Nottingham
Department Name: Division of Infrastructure and Geomatics


A range of highly adventurous, speculative, short-term, cross-disciplinary feasibility studies will be undertaken as a collaboration between the Nottingham Transportation Engineering Centre (NTEC) at the University of Nottingham, the 'Adhesion, Adhesives and Composites Group' at Imperial College London and the 'Materials Engineering Group' at Texas A&M University. The feasibility studies will be in the general area of the physicochemical characterisation of asphalt materials and address the adhesive properties and interfacial relationships between the material components using a range of cross-disciplinary techniques and testing methods developed during a Collaborating for Success through People Grant. In addition, the feasibility studies will be extended into new research areas that are linked with the general area of the physicochemical characterisation of asphalt materials through cross-disciplinary collaborations with groups in Organic Chemistry, Chemical Engineering and Nanotechnology.The feasibility studies will be undertaken by post-doctoral researchers (PDRAs) working in the area of asphalt technology and pavement materials at NTEC. The PDRAs will be bought out of their existing projects and seconded for the period of the Feasibility Account to undertake these dedicated, cross-disciplinary feasibility studies. Successful areas of cross-disciplinary research resulting from the short-term research studies, in terms of their potential to have a significant impact on society and the economy, will be identified through a series of workshop, seminars and sandpits and built into large scale research proposals and projects.

Planned Impact

The UK road network alone has a length of 417,000 km, an asset worth some 600bn, accounts for about 93% of passenger kilometres travelled and some 73% of the tonne kilometres of goods traffic. The importance of the nation's road infrastructure to the economy, society and quality of life are enormous. Maintaining this asset is a very expensive cost to the economy. Local Authorities in England and Wales alone spend 2.5bn annually on road maintenance. Most importantly, maintaining and rehabilitating this asset while at the same time reducing traffic delays and implementing sustainability, has placed increased emphasis on the need for high-performance, and increasingly more durable, pavement materials. The feasibility projects in this proposal will investigate a step change in practice that has potential for a major impact on the industry by substantially reducing maintenance costs and implementing good sustainable practice. For example, the proposed work on developing composites with longer life adhesion characteristics that resist cracking and water ingress has the potential of making a major impact on the economy and the public sector by substantially reducing maintenance costs and travel time delays. The impacts will therefore be wide ranging as follows: Commercial sector and industry impacts The key potential impacts will be major new business opportunities, enhancement of competitiveness and the opening of new markets by having a worldwide technological lead. Binder and aggregate industries, for example, could benefit from a market lead in new highway materials/composites and processes that will substantially reduce maintenance costs. Timescales for significant commercial impacts are likely to be in the 5-15 year timescale. Broader economic impacts An industry technological lead will enhance the competitiveness of the UK and our economic success in overseas markets. New highway material markets will create new jobs, both in the supplier industries (which may be different to the existing ones) and from new export markets for the UK economy. Development of projects to larger scale projects will provide trained staff for the economy in these new cross disciplinary areas should the technologies move over to a commercialisation phase. Reduction in travel time and delays on roads has a significant benefit to the economy. Impact on government and policy makers If the feasibility projects look promising, key government stakeholders such as the Highways Agency and the DfT will see major benefits from supporting future work. They will see significant potential impact from the substantial reduction of maintenance costs and travel times and/or the implementation of good sustainable practice. Interest could translate very quickly into active support for EPSRC/TSB funding proposals. Societal impacts In the longer term impacts on society include a better quality of life from reduced travel times and a move to greater sustainability. People impacts The provision of trained people with the cross disciplinary expertise necessary to create new products and develop the UK's economic and sustainability aspirations. Impact implementation plans A range of measures will be implemented to ensure maximum impact including: - The proactive participation of the Business Development Manager to: ensure maximum industry and policy maker involvement throughout the programme; arrange dissemination activities and the development of an action plan to secure ongoing funding for promising areas; and to monitor the potential for new IP emerging from the work. - Workshops and seminars with industry and policy maker involvement (particularly the Highways Agency) - Use of Nottingham Asphalt Research Consortium (NARC) to promote the outputs of the work - A final symposium aimed at the non academic community including industry and policy makers


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Description This EPSRC research project focussed on the development and consolidation of cross- and inter-disciplinary research links between researchers in civil, mechanical, material, and chemical engineering as well as organic chemistry, based at three institutions in the UK and US. The research was targeted at asphalt (bitumen-bound) pavement materials used as the riding surface or underlying structural layers of a road and involved a number of short-term, speculative feasibility studies addressing key areas of material performance. The specific, project-focussed, cross-disciplinary, speculative feasibility studies have addressed issues such as the adhesive and cohesive properties of asphalt materials; the production of alternative synthetic and environmentally sustainable binders/adhesives; and the use of nanotechnology to increase the understanding of asphalt mixture failure and distress mechanisms.

The research has shown that through a combination of thermodynamic surface free energy and adhesion fracture energy measurements, it is now possible to understand, predict and even enhance the resistance to moisture damage of asphalt mixture pavement materials. This truly fundamental approach to the understanding of moisture damage will allow the appropriate selection of asphalt mixtures components to deliberately mitigate its effect on the long term stability of the road material. The research used a combination of adhesive fracture energy measurements on bitumen-aggregate systems using monotonically-loaded tests together with intrinsic adhesion calculations based on thermodynamic surface free energy concepts to produce a step change in the moisture damage performance and material screening of asphalt mixtures. The introduction and development of these new methods and novel approaches will provide the tools needed for the better selection and water induced damage prediction of appropriate pavement materials. This combined approach contributes effectively to improving the understanding and prediction of such damage in asphalt mixtures and thereby provides a tool to achieve the project goal of enhancing moisture damage performance.

The research collaboration between chemistry, chemical engineering and pavement materials has also shown that it is possible to produce synthetic polymers, with similar rheological properties to conventional bitumen, through catalytic chain transfer polymerization (CCTP). A range of methyl acrylate (MA) and butyl acrylate (BA) synthetic polymers of specific, targeted molecular weights and with polydispersity index values in the range of 2 - 4.5 were subjected to standard rheological and viscometry testing. The results showed that it was possible to produce a range of synthetic polyacrylates with different rheological responses by altering the reactant type, reactant concentration and polymerization conditions to match the rheological properties of road bitumens. These findings suggest that sustainably sourced, polyacrylate binders may allow a move from petrochemical feed stocks to be made. In addition, the ability to engineer these synthetic binders should allow them to be targeted to specific road pavement design requirements based on local climates, predominant distress mechanisms and traffic levels by offering improved mechanical robustness.

This research project has provided a crucial step in managing the risk and reliability of the UK highway infrastructure by improving the understanding of pavement distress and material response through a series of cross-disciplinary studies incorporating the skills and expertise of these different disciplines. With the highway network being the largest UK infrastructure asset worth some £600bn, establishing these interdisciplinary teams to tackle the performance of asphalt paving materials is considered extremely timely.
Exploitation Route The asphalt construction industry have plans to use the screening tests developed in the grant to optimise material selection in order to reduce future failures and decrease maintenance costs.

The work on synthetic binders has been used to produce binder rejuvenators that are critical to the successful use of reclaimed asphalt pavement (RAP) material in recycled asphalt materials.
Sectors Construction,Transport

Description The impact of the research has been slow due to the traditionally conservative approach of the pavement engineering construction industry. However, aspects of the research (screening procedures for pavement materials and the production of synthetic or bio-binders) are now being used by construction companies in the UK and Europe.
First Year Of Impact 2013
Sector Construction
Impact Types Economic