PhD | Impact of carbonation on corrosion, mechanical and transport properties of blended cements

While cement production is expected to get doubled by 2050, blended cements are adopted more by the concrete industry to reduce the carbon footprint of concrete. In Belgium, 60% of the total cement sold in 2018 was allocated to blast furnace slag cement (CEM III) and 40% of it was Portland cement (CEM I, II and V) including cements blended with supplementary cementitious materials (SCM). Among the most commonly used SCM, blast furnace slag (BFS) is utilized almost fully in cement making while the availability of fly ash is strikingly decreasing. Hence, calcined clays as new SCM are emerging to replace Al-Si rich fly ash. Over the past decade significant studies have emerged on ternary blended cements with calcined clay and limestone, known as LC3 cements with a clinker factor up to 50%. However, carbonation is still the major durability concern of blended cements. Despite the most recent works exploring the carbonation mechanism of cement(-SCM) hydrates, there is still a need for a systematic analysis of carbonation-induced modifications in the microstructure and transport properties in order to maximize carbonation resistance of concrete incorporating more and emerging SCM, and to accurately predict carbonation ingress and service life of concrete structures. Also, as limited experimental duration is typically devoted in the carbonation experiments, it is therefore of utmost importance to develop a new model to accurately predict the long-term carbonation based on the short term natural/accelerated tests.

This PhD project adopts a multiscale approach in which carbonation kinetics and microstructural alterations of single (e.g. CH, C(-A)-S-H, AFm, AFt) and multiple hydrates (at paste scale) are coupled with the transport properties and carbonation modelling (at mortar scale) to elucidate the origin of carbonation-induced alterations in microstructure and transport process of SCM-containing cements that have been and will be extensively used in concrete structures. This is imperative to resolve the vulnerability of these cements to carbonation, to accurately predict long-term carbonation ingress and to determine the best strategies to increase durability of concrete structures against carbonation-induced reinforcement corrosion. In this project, we will bridge this crucial research gap with a detailed study on the carbonation of blended cements (OPC – BFS – Metakaolin). These findings will be an essential input for the development of the new carbonation model incorporating reaction transport processes.

Job description

• You prepare a doctoral thesis, which will be supervised by a promotor from KU Leuven University, Belgium and mentors from SCK CEN.
• The PhD project is fully funded by The Research Foundation - Flanders (FWO).
• You work together with another PhD in a FWO fundamental research project on carbonation of blended cements
• You conduct research and publish scientific articles related to this PhD research project.
• You will be part of an international, interdisciplinary team.
• You will mainly work at SCK CEN in Mol, Belgium and partially work at KU Leuven University, Belgium

Required profile

• You hold a Master degree in civil engineering or related degrees. Students in the final year of their degree can also apply.

• You have an excellent background in cement/concrete degradation (both modelling and experimental).
• You have a strong interest in interdisciplinary research.
• You are quality-oriented, conscientious, creative and cooperative.
• You have mastered the English language, both in writing skills and oral presentations.
• You are interested in working in an international environment.

We offer

• A doctoral scholarship for a period of 4 years with competitive salary
• A dynamic and stimulating work environment
• Involvement in a FWO project and other European projects
• Stimulation to self-improvement by encouraging participation in courses, workshops and conferences
• Close supervision and guidance in conducting the planned research by a supervisory team from SCK CEN and KU Leuven University.

How to apply?

Please follow the application guidelines posted on SCK CEN’s website: https://www.sckcen.be/en/sck-cen-academy/phd-theses-post-docs/phd-theses/how-do-i-submit-my-phd-candidate

Note that this PhD project can start as soon as an excellent candidate is selected (not necessary to follow the regular timeline of SCK CEN PhD’s program). Before applying, it is compulsory to first contact the SCK CEN mentor for further information. When contacting the mentor, please prepare an application file giving following information:

• A short CV with a summary of your career
• A motivation letter
• A copy of relevant diplomas
• Transcript of study records