Supervisors

Dr Prakash Kripakaran, Department of Engineering, University of Exeter

Professor Daniel Franks, Sustainable Minerals Institiute, University of Queensland

Additional Supervisors:

Lele Vinai, Department of Engineering, University of Exeter

Vinh Dao, School of Civil Engineering, University of Queensland

Paul Rogers, Sustainable Materials Institute, University of Queensland

Join a world-leading, cross-continental research team

The University of Exeter and the University of Queensland are seeking exceptional students to join a world-leading, cross-continental research team tackling major challenges facing the world’s population in global sustainability and wellbeing as part of the QUEX Institute. The joint PhD programme provides a fantastic opportunity for the most talented doctoral students to work closely with world-class research groups and benefit from the combined expertise and facilities offered at the two institutions, with a lead supervisor within each university. This prestigious programme provides full tuition fees, stipend, travel funds and research training support grants to the successful applicants.  The studentship provides funding for up to 42 months (3.5 years) for home and international students.

Eight generous, fully-funded studentships are available for the best applicants, four offered by the University of Exeter and four by the University of Queensland. This select group will spend at least one year at each University and will graduate with a joint degree from the University of Exeter and the University of Queensland.

Find out more about the PhD studentships click here

Successful applicants will have a strong academic background and track record to undertake research projects based in one of the three themes of:  Healthy Living, Global Environmental Futures and Digital Worlds and Disruptive Technologies.

The closing date for applications is mid-day Friday June 28th 2024 (BST), with interview to be w/c 29th July 2024 (tbc). The start date is expected to be Monday January 6th 2025.

Please note that of the eight Exeter led projects advertised, we expect that up to four studentships will be awarded.

Supervisors

Exeter Academic Lead: Dr Prakash Kripakaran

Queensland Academic Lead: Professor Daniel Franks

THEME - Mineral Security and Sustainability

Project Description 

The construction sector is a major contributor to global carbon emissions, as the production of ordinary Portland cement (OPC) accounts for over 8%. Consequently, finding viable alternatives to OPC that are cost effective while having a much smaller carbon footprint is a key focus within the sector. Limestone + calcined clay cements are a promising new development that has been demonstrated to have by 40% less CO2 emissions than OPC and is already undergoing field trials in the UK (e.g., at Network Rail). However, the availability of the key ingredient – calcined clays, remains a bottleneck, impacting the viability and scalability of LC3 in practice. Furthermore, the valorisation of large quantities of biogenic calcium carbonate materials, byproducts of food industries in coastal areas worldwide, have not been fully realised yet. This project aims to investigate the feasibility of low carbon cementitious system including low grade clays (kaolin), which is abundantly available in the UK and is often produced as a waste in the mining sector, and biogenic calcium carbonate, sourcing secondary raw materials for the manufacture of LC3 cements. The project will work mainly with mining companies in Cornwall, with whom the engineering department at Exeter have strong links. The work will have two strands.

One strand will be about the material characterisation, processing parameters, and mechanical performance of cements made from low grade clays arising in waste streams from mining companies. This strand will characterise the material composition of waste clays that are currently destined for landfill sites and work through the processing pathways to produced calcined clay cements. It will also consider the potential for using seashells as a substitute for limestone. The second strand of the work will focus on the lifecycle assessment and circular economy impact of the resulting calcined clay cements. This strand will examine the material flows and draw upon the results from experimental work to provide a means to evaluate the potential savings in carbon. It will also help formulate a systematic approach to scale up the processes developed in laboratory settings for industrial applications both within the UK and Australia, as well as elsewhere such as in India through our partners.

Ordinary Portland cement (OPC), which remains the predominant building material in the construction sector, is responsible for over 8% of the emissions. The construction sector has therefore been exploring a range of alternatives for OPC. An important recent development is the limestone calcined clay cements (LC3), pioneered by the work of Scrivener et al. (2018) [1] . LC3 has been demonstrated to have a carbon footprint that is 40% less than OPC and offers potential to significantly reduce CO2 emissions in the cement sector. However, current methods of LC3 production rely on clays with very high levels of kaolinite, which is naturally available only in limited locations geographically and therefore unsuitable for scale-up. The use of low grade clays, which are available abundantly in the UK and often generated as a waste in the mining sector, for LC3 remains an open research question.

This research aims to address this challenge. Further to that, it will also examine the use of biogenic calcium carbonate (from sea shells) as an alternative to limestone as filler in concrete or as a raw ingredient for clinker production – which can further reduce embodied carbon and directly benefit coastal economies that significantly rely on seafood and produce localised amount of shells. The aim of this project is hence to investigate the potential for using low grade clays, such as those generated by the mining sector in Cornwall, and biogenic calcium carbonate sources for LC3 and its positive benefits for sustainability and circular economy.

The specific objectives are as follows.

1. Characterise the compositional properties of waste clays sourced from Cornwall through materials analysis.

2. Investigate processing pathways for calcination and develop the optimal parameters for processing to achieve the desired chemical and compositional properties.

3. Undertake microstructural characterisation (FTIR, SEM, XRD) of cement pastes produced with calcined clays and biogenic calcium carbonate.

4. Assess the mechanical properties (compressive and flexural strength) of mortar and concrete samples produced with the waste-based LC3 cement.

5. Assess the availability of the identified secondary raw materials to determine the viability of LC3 cement production in the targeted areas.

6. Perform lifecycle analysis (LCA) to assess the energy and emission impacts of material flows in the preparation of calcined clay cements and formulate approaches for scaling up developed processing methods.

The PhD will have two main work strands, both leveraging expertise of the academics at the two institutions.

1. Materials processing and characterisation: This work will use the experimental facilities (XRD, TGA FTIR, SEM) at Exeter and Queensland for understanding the chemical and mineralogical composition of the clays and processed raw materials, as well as on reaction products later in the study. The kiln at Exeter will be used to investigate the calcination step, assessing the impact of temperatures and duration of the process on the reactivity of the materials through XRD, FTIR and TGA. The student will then undertake early age shrinkage and macro properties (compression strength etc) at Queensland drawing on their expertise in this area.

2. LCA and circular economy: The student will use SimaPro or similar tool for LCA. The energy and material flows will be modelled according to the process pathways identified in the first work strand. Industry input will be sought on scaling up of the processes. [1] Scrivener, K., Martirena, F., Bishnoi, S. and Maity, S., 2018. Calcined clay limestone cements (LC3). Cement and concrete research, 114, pp.49-56.

Entry requirements

Applicants should be highly motivated and have, or expect to obtain, either a first or upper-second class BA or BSc (or equivalent) in a relevant discipline.

If English is not your first language you will need to meet the English language requirements and provide proof of proficiency. Click here for more information and a list of acceptable alternative tests.

How to apply

Apply now

Owing to essential maintenance, SRS will be unavailable between 17:00 BST on Thursday 27th June and 09:00 BST Monday 1st July 2024, which means you are unable to submit an applications during this time.
The application deadline will therefore be extended until 12:00 BST on Wednesday 3rd July.
Please accept our apologies for any inconvenience caused.

You will be asked to submit some personal details and upload a full CV, supporting statement, academic transcripts and details of two academic referees. Your supporting statement should outline your academic interests, prior research experience and reasons for wishing to undertake this project, with particular reference to the collaborative nature of the partnership with the University of Queensland, and how this will enhance your training and research.

Interview notifications date TBC

Please quote reference 5160 on your application and in any correspondence about this studentship.

Summary