PhD position Carbonatable binders and their reaction mechanisms

Concrete production is a major contributor to global anthropogenic CO₂ emissions, with Portland cement, the primary binder used in conventional concrete, accounting for the largest share of these emissions. As a response to this challenge, carbonatable binders have emerged as promising alternatives capable of offering CO2-negative solutions for certain concrete applications in the built environment.

The term carbonatable binder broadly refers to alternative binders that, unlike conventional Portland cement, harden through a reaction with CO₂. This carbonation process results in the binding of CO₂ into solid carbonate products, which contribute to the microstructure of the carbonated binder and its strength development. Examples of carbonatable binders include steel slags and synthetic clinkers based on Ca- and/or Ca-Mg-silicates.

The state of the art on carbonatable binders focuses mostly on binders that rely on the reaction of Ca-rich precursors, e.g, portlandite (Ca(OH)₂), belite (Ca₂SiO₄), and wollastonite (CaSiO₃). However, recent research carried out by VITO has shown that some Ca-Mg-silicates, in particular akermanite (Ca2MgSi2O7), also hold promising reactivity towards mineral carbonation under certain reaction conditions, i.e., pressure, CO2 concentration. The carbonated products based on the reaction of Ca-Mg-silicates with CO₂ can also achieve high strength, being suitable for construction applications. This finding has unlocked a new avenue for the use of Mg-silicate-rich residues such as slags and mine tailings as raw materials in the production of carbonatable binders.

While those Ca-Mg-silicate-based carbonatable binders hold significant potential for large-scale CO₂ capture in construction materials, many questions remain regarding the relationship between the reactivity of binder phases and the resulting microstructure and properties of the carbonated products. This PhD project seeks to address these knowledge gaps by advancing the fundamental understanding of carbonatable binder reactions and thereby enhancing their positive impact.

Within this PhD project, the student will develop expertise in high-temperature synthesis, carbonation experiments, materials characterization, microstructural analysis, and solution chemistry.

PhD supervision

The research will be conducted primarily at VITO in close collaboration with KU Leuven. The successful candidate will be supervised by Prof. Ruben Snelling (KU Leuven) and co-promoted by Dr. Natalia Pires Martins (VITO).

How to apply?

Applications should be submitted online and include a copy of your CV, diploma transcripts and a cover letter.

More information about the application procedure is available on the VITO website.

Overview of the jury’s scheduled in 2025 and deadlines: https://vito.be/en/jobs/phd/phd-jury.

Start date: 01/01/2026

• Master in Geology, Geochemistry, Chemical or Materials Engineering, Materials Science, Metallurgy, or similar.

• Strong analytical problem-solving skills

• Creative, critical and hand-on mentality

• Good oral and written communication skills in English