Ageing Multiphysics of Asphalt Materials

Periodic Reporting for period 1 - AMAM (Ageing Multiphysics of Asphalt Materials)

Période du rapport: 2017-09-21 au 2019-09-20

Bitumen (or asphalt binder) is a by-product of crude oil distillation and is heavily used as a binder for transport infrastructures, especially for the surface paving of roads, highways, bridges, and airport runways, with additional applications in house roofing and structural joint sealing. Asphalt materials (AMs) are referred in this project to the bitumen-based construction materials including asphalt binder and mixtures such as mortar, mastic and concrete when mixed and compacted with mineral aggregates. It has been demonstrated that bitumen is an extremely complex compound material composed of thousands of different types of hydrocarbons, paraffinic, aromatic, and naphthenic with varying saturations, polarity, function groups and heteroatoms such as oxygen, nitrogen and sulfur. Complexity becomes more serious for the asphalt mixtures due to the adhesion characteristics between bitumen and aggregates as well as the inclusion of air voids and pores in the mix. A further layer of complexity is added by the ageing nature of the AMs. It has been observed that the AMs will age with extension of service time and long-term exposure to natural environments such as solar radiation, oxygen, and moisture. The ageing of the AMs leads to degradation of the material’s physical, chemical, and mechanical properties, which can cause the deteriorations of the materials and distresses in the structures, and eventually result in the reduction of the structural service life and waste of natural resources. Thus an increasing demand has been raised for a comprehensive understanding and prediction of the AMs’ ageing performance and the development of new materials, additives and technologies for anti-ageing and rejuvenation of the aged AMs.

The overall objectives of this project included five aspects: 1) training of the Fellow’s academic expertise, professional skills and inter-sectoral collaboration; 2) investigation of multiphysics ageing mechanisms of AMs; 3) Modelling of multiphysics circular dependences and computational performance prediction of AMs; 4) development of anti-ageing materials and evaluation technologies for AMs used in industry; and 5) industry application of ageing evaluation framework and anti-ageing materials in new and recycled AMs. The project potential benefits were achieved by: 1) a better understanding of AMs’ ageing mechanisms to accelerate the material suppliers in developing and improving anti-ageing additives for bitumen to be used in transport infrastructures for service life extension; 2) an accurate performance prediction of aged AMs to allow transport consultancy, construction contractors and highway agencies to optimize standards, design, construction, and maintenance of the infrastructures; and 3) anti-ageing modelling and materials used in sustainable technologies, e.g. warm mix asphalt (WMA), reclaimed asphalt pavement (RAP), alterative renewable binders (e.g. bio-bitumen), etc. for construction projects to reduce greenhouse gases and save natural resources.

There are five work packages undertaken through the project, which are elaborated as follows.

Month 1 - Month 24
Work Package 1: Overall training-through-research.
Extensive training activities were taken by the Fellow to enhance his expertise in multiphysics modeling and advanced material characterisation, in addition to project management, communication and networking skills developed through the project.
Main Outcome: A well-trained researcher with competitive academic knowledge and management skills.

Month 1 - Month 12
Work Package 2: Investigation of multiphysics ageing mechanisms of asphalt materials.
The Fellow focused on the circular dependent multiphysics for the ageing mechanisms of an asphalt mixture. The models for interrelated multiphysics contained: 1) chemical oxidation model including bitumen compositional analysis, and oxidative kinetics models; and 2) environmental physics including temperature profile by heat transfer, moisture diffusion and oxygen distribution.
Main Outcome: A working paper was prepared for submission.

Month 4 - Month 15
Work Package 3: Development and validation of multiphysics ageing models for asphalt materials.
The Fellow utilized the Comsol Multiphysics program to convert the models for different physics developed in Work Package 2 into weak-form partial (or ordinary) differential equations (PDE) and developed an asphalt pavement model considering multiphysics ageing. The model was validated using the extensive data from the literature.
Main Outcomes: Two papers were published on academic journals. One poster presented at the EATA Conference in Spain.

Month 7 - Month 21
Work Package 4: Experimental characterisation and an anti-ageing evaluation protocol.
The Fellow examined twenty different anti-ageing compounds (AACs), including new and existing AACs for bitumen and polymer products. The Fellow found that AACs exhibiting high anti-ageing performance were those contained furfural and DLTDP.
Main Outcomes: One paper was published on academic journal, and one poster was presented at the TRB Meeting in Washington, D.C.

Month 6 - Month 24
Work Package 5: Industry applications and feedbacks.
The Fellow and the hosts focused on implementing the developed multiphysics ageing modelling framework on the industry asphalt materials. Knowledge transfer and research network was induced through the industry placement of the Fellow in the industry partner institutions.
Main Outcomes: Organised six seminars and two workshops at the different organisations.

Overview: Through this project, the Fellow gained competitive academic knowledge and management skills, published three technical papers in academic journals, prepared one working paper, and organised six seminars and two workshops to disseminate the research findings.

Expected Results
The project led to a number of publishable scientific results (e.g. journal articles and conference proceedings), and applicable industry practices (e.g. performance framework and anti-ageing effectiveness evaluation protocol).

Research Impact on the Fellow
The multidisciplinary research in this project helped the Fellow to reach his mid-term professional goal of attaining a leading and independent position in Academia. The training performed in this project significantly extended the Fellow’s expertise from mechanics and experimentation to chemistry, and material science coupled with valuable professional skills such as project management, collaboration and communication.

Research Impact on the Whole Society
The results of the project were disseminated and published to the most extent via multiple communication platforms such as printed publications, conference presentations, workshops, seminars and so on, targeting a variety of potential users and partners including material companies, infrastructural designers, engineers, managers, contractors, and researchers throughout Europe and the world.

Research Impact on the Local Community
The main host organized a series of outreach activities to encourage a great interest in science among university, school students and general public. The Fellow joined in the host’s initiative of multi-media releases for publication on the University websites and Personal Research Website for public access. During the industry placement, the Fellow brought innovative ideas to the industry companies through workshops and seminars for collaboration.

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Periodic Reporting for period 1 - AMAM (Ageing Multiphysics of Asphalt Materials)

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