The UK produces approximately 3 million tonnes of processed incinerator bottom ash (IBA) each year from the combustion of municipal solid waste. Although coarse IBA is used in road construction and some concrete products, the fine fraction is frequently landfilled because of its low reactivity, variable composition and potential environmental risks. It can also contain metallic aluminium, which reacts under the alkaline conditions found in cementitious materials and releases hydrogen gas, causing expansion and void formation. Developing an effective treatment for fine IBA could therefore turn a problematic waste stream into a valuable low-carbon construction material.
This PhD project will investigate a novel one-step mechano-chemical treatment that integrates wet grinding, alkaline activation and accelerated carbonation. The process is intended to reduce the particle size of IBA, enhance its pozzolanic reactivity, consume reactive aluminium and permanently bind carbon dioxide as stable carbonate minerals. The project will also explore the use of concrete washout water as an environmentally responsible alkaline treatment medium, creating opportunities to valorise two construction-related waste streams simultaneously.
The successful candidate will optimise key treatment parameters, including liquid-to-solid ratio, grinding speed, carbon dioxide flow rate and treatment duration. Changes in the physical, chemical and mineralogical properties of IBA will be examined using techniques including X-ray diffraction, thermogravimetric analysis, Fourier-transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, scanning electron microscopy, BET surface-area analysis and particle-size measurements.
Optimally treated IBA will be incorporated into cementitious binders as a 5-20% replacement for cement. The candidate will investigate fresh properties, rheology, hydration behaviour, phase assemblage, microstructure, mechanical performance and volume stability. Leaching tests will be used to assess the environmental safety of both the treated IBA and the resulting hardened materials. The project will also examine whether carbonated process water can be reused in subsequent treatment cycles or in cementitious binders, reducing freshwater consumption and wastewater generation.
The research is expected to deliver a better fundamental understanding of how grinding, alkaline activation and carbonation interact to modify IBA. It will also establish whether treated fine IBA can provide a technically effective and environmentally safe cement substitute. The wider ambition is to reduce waste disposal, lower dependence on Portland cement, support carbon dioxide sequestration and advance circular material use within the construction sector.
The student will receive multidisciplinary training in cement and concrete science, waste treatment, mineral carbonation, experimental design, advanced materials characterisation, environmental testing and quantitative data analysis. They will join a supportive research environment and develop transferable skills through regular supervision, research presentations, conference participation and preparation of peer-reviewed publications.
This project is expected to start in September 2027.
Before you apply: We strongly recommend that you contact the supervisors for this project before you apply.
How to apply: To be considered for this project you must complete a formal application through our online application portal. If you already have an applicant account this link will directly open an application for PhD School of Engineering Scholarships. If you don’t already have an applicant account, please follow the instructions here..
When applying, please specify the full title and supervisor/s of the project, details of your previous study, and names and contact details of two referees. You must also upload a Supporting Statement describing the motivation to apply to the project, your CV and transcripts of awarded and in-progress university qualifications. Please note late or incomplete applications will not be considered.
Equality, diversity and inclusion are fundamental to the success of The University of Manchester and central to all our activities. A diverse research community strengthens creativity, productivity and quality, while increasing the societal and economic impact of our work. We welcome applicants from all career paths, backgrounds and sections of the community, regardless of age, disability, ethnicity, gender, gender expression, sexual orientation or transgender status.
We welcome applications from candidates returning to study after a career break or experience in other roles. Flexible study arrangements may be available, including part-time study at 50%, 60% or 80%, subject to the requirements of the project and funder.
Eligibility: The standard academic entry requirement for this PhD is an upper second-class (2:1) honours degree in a discipline directly relevant to the PhD such as civil engineering or material science (or international equivalent) OR any upper-second class (2:1) honours degree and a Master’s degree at merit in a discipline directly relevant to the PhD such as civil engineering or material science (or international equivalent).
This project will remain open until filled.
If your application is submitted by 1st November 2026, you can expect a decision by 18th December 2026.
If your application is submitted by 15th January 2027, you can expect a decision by 30th March 2027.
Self or externally funded students can also be considered for this project.
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