Oxidation kinetics and diffusion behaviour of ferrous ions in cementitious media

Background

Tremendous CO₂ emissions caused by industrial production and human activities are leading to severe situations for society and the environment. One of the major sources of CO₂ emissions is the production of cement. Concrete is one of the most used materials on the planet, indicating that concrete may potentially act as a carbon sink at large scale. However, critical modifications and fundamental understanding are needed, namely to speed up the relatively slow process of natural CO₂ sequestration in concrete, and to ensure the durability of the structures in case they are still to be used.

There is already research focusing on CO₂ sequestration in concrete, such as bio-concrete. Bio-concrete usually refers to self-healing concrete that is designed to repair the cracks without human interference. The mechanisms for bio-concrete self-healing are based on microbiologically induced calcite precipitation (MICP). Carbonate and bicarbonate ions are produced during metabolism activities of the living organisms. With the presence of Ca²⁺ in the concrete, CaCO₃ precipitation takes place and will help to increase the strength and durability of concrete by healing the cracks inside or outside the concrete. However, these approaches do not always start from atmospheric CO₂ and so their carbon sequestration capacity may be limited.

Aims and objectives

We aim to achieve CO₂ sequestration and improve the durability of concrete with the help of living organisms such as bacteria and fungi. By understanding how living organisms can live and grow inside the concrete, and the mechanisms of CO₂ sequestration by biomineralization process, we strive to enhance the carbon sequestration capacity of concrete. Characterization of the bio-hybrid concrete will provide insight into how living organisms interact with concrete and in return how the properties of concrete are affected by the incorporation of living organisms.