Predicting the carbon-neutral progress of cement-based materials in their whole service life

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As the world most widely used material after water, cement-based materials have over 4.1 billion m3 of annual consumption. Although manufacturing such materials instigates ~8% of global embodied carbon, the final products could reabsorb atmospheric CO2 and incorporate it as a stable form of CaCO3 or MgCO3 by natural carbonation throughout their service life. In addition, the recycled aggregate, prepared by concrete waste (~400 million tonnes annually in the EU and 70% has been directly used as road materials), has an unleashed potential to reabsorb the CO2 from industrial waste gas by accelerated carbonation.The challenge is to accurately predict the contributions of the embodied carbon and the reabsorption of CO2 to the carbon-neutral progress of cement-based materials throughout their service life. Attempts have existed to address this challenge, but these are very controversial. Therefore, this project aims to address the challenge by developing a carbon-neutral model for various cement-based materials and applications. The key scientific issue is understanding and predicting the formation and distribution of CaCO3 or MgCO3 in various cement-based materials. Therefore, many theoretical models will be developed to model the CO2 diffusion and reaction behaviour in hardened cement pastes based on the microstructural evolution and phase composition of such materials under carbonation. A software package and its guidelines manual, together with some case studies, will be proposed for the carbon- neutral model to be widely used. In addition, several dissemination and public engagement activities are designed to improve the impact of this project.The proposed modelling techniques will provide IPCC and EC Construction Sector with an approach to evaluate the carbon-neutral progress of cement-based materials. It will, in turn, offer EC Environment Department a specific quantitative estimation to propose policies to speed up the carbon-neutral progress.