Circular Roads: Improve Recycled Asphalt Content in Pavements by better understanding of Compaction Mechanics

Asphalt recycling gained prominence since the 1970s, partly initiated by the oil crisis influencing the availability of bitumen as binder material. Since then, recycled and reclaimed asphalt continued to be part of the mix used in road and pavements providing a cost effective and environmentally friendly option with a potential to decarbonising the industry. Recent examples of roads using recycled asphalt include: 50% recycled asphalt was used in paving a section of M25 between junctions 25 and 26 and a section of A388 Bournemouth Spur Road, Dorset was paved using all the old road materials.  

Rolled asphalt pavement comprises of different courses primarily the wearing, binder, base, subbase and capping layer. The degree of compaction determines the stiffness and strength of material along with its resistance to deformation and durability of the mixture. Compaction of the asphalt along with the binder results from the operation of the paving/construction equipment to impart systematic static, shearing and vibrational loads to achieve the required properties of each of the aforementioned course. The pavement is expected to withstand the design traffic load.  

In the drive towards net zero carbon emission, there is an urgent need to significantly increase the use of the 100% recyclable Recycled Asphalt Pavement (RAP) in pavement construction.  This poses significant challenges in the design and optimisation of the production and construction processes for which this current project seeks to address. For instance, is it possible to better characterise the RAP in terms of material properties to provide a more accurate initial assessment of its recycling readiness? Is it possible to match to assess, based on the RAP's material characteristics and the prevailing loading regimes, whether it would meet the required highway standards?  

The aim of the project is to develop a deeper understanding of the RAP pavement construction and establish an experimentally calibrated numerical model to predict the compaction mechanics of recycled asphalt pavements during construction as well as operational period. The model will integrate the mechanics at different length scales. Experimental programme will include time-resolved (4D) X-ray tomography to capture the micromechanics of the granular assembly.  

This PhD project is advertised as a part of the Edinburgh Research Partnership in Engineering, a joint partnership between the University of Edinburgh and Heriot-Watt University. The successful candidate will be supervised by a team consisting of academics from the University of Edinburgh and Heriot Watt University (HWU). The Heriot-Watt University supervisor for this project will be Dr Elma Charalampidou. Some of the experiments involving micro x-ray CT system will be undertaken at HWU.

The selection process is in two phases:

Stage 1: Interested candidates should contact Dr Amer Syed at Amer.Syed@ed.ac.uk by 7 February 2025 with their CV and a covering email. Potential candidates will be invited to an interview. Selected candidate will progress to Stage 2.

Stage 2: Selected candidate will complete a formal application to the University of Edinburgh by 12 February 2025. This application will be assessed by a panel for funding. Please note that this studentship attracts enhanced stipend, while the exact details yet to be finalised, for 2024, it was £21,400 per annum.

Home and overseas students are encouraged to apply. 

The University of Edinburgh is committed to equality of opportunity for all its staff and students, and promotes a culture of inclusivity. Please see details here: https://www.ed.ac.uk/equality-diversity 

Minimum entry qualification - an Honours degree at 2:1 or above (or International equivalent) in a relevant science or engineering discipline, possibly supported by an MSc Degree. Further information on English language requirements for EU/Overseas applicants.

Tuition fees + stipend are available for Home/EU and International students.

Further information and other funding options.