Immanuel Rwandalla

PhD student Immanuel Rwandalla is part of a specialist department at the University of South Wales (USW) which is looking at ways to make the construction industry more sustainable.

And it’s been one of his passions since he studied an Advanced Engineering Materials module as part of his for his Masters at USW, when he became interested in ways to develop stronger, cleaner, and more sustainable construction materials.

Originally from Tanzania, Immanuel’s academic journey began with a Bachelor’s degree in Civil Engineering in China, then his Masters in Structural and Civil Engineering at USW – which he started in 2020 – before a return to Tanzania to consider his options.

Then, in 2024, he resumed his academic path, embarking on a PhD at USW. The Masters module raised Immanuel’s interest in developing more eco-friendly construction materials, and his PhD research aims to create high‑strength concrete while dramatically reducing the amount of cement needed to produce it.

“I’m looking at ways to replace a significant proportion of cement – which is very high in carbon dioxide - with industrial by‑products that would otherwise contribute to waste streams,” he said.

“The research done by the team I’m part of has been looking at a number of materials - such as metakaolin, ground granulated blast furnace slag (GGBS), and silica fume - which provide a promising alternative.

“These by‑products, sourced from metal refining and other manufacturing sectors, offer the dual advantage of lowering concrete’s carbon footprint while potentially enhancing its mechanical performance.”

Immanuel added that the research focuses on determining how much of these materials can replace cement without compromising compactibility, strength, and durability.

“Typical substitution levels range between 10% and 40%, and each brings its own effects on how concrete behaves during curing and long‑term use,” he said.

“The challenge is to strike a balance that delivers both structural reliability and meaningful reductions in environmental impact. The ultimate goal is to produce concrete formulations that the construction industry can adopt confidently and at scale.”

Immanuel also has positive views of the culture within the research team.

”My PhD supervisors Dr Jiping Bai and Dr Jonathan Oti are familiar faces from my Masters, are experts in this field, and really help to dive my work forward,” he said.  

“Having such specialists in concrete technology is really valuable, they provide strong guidance and ensures the research remains rigorous, relevant, and innovative.”