A fundamental model of coupled carbonation-hydration curing for optimal early-age performance of low CO2 binders

• Applicant: Dr. Fabien Georget
• Subject Area: Construction Material Sciences, Chemistry, Building Physics ; Thermodynamics and Kinetics as well as Properties of Phases and Microstructure of Materials
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 542120441

Our project aims to tackle both the issue of lower early-age performance of low CO2 binders, and carbon capture and utilization by mineral carbonation (CCUM). Early-age performance is one of the main obstacles concerning the increase of the substitution of clinker by supplementary cementitious materials (SCMs). To maximize the potential of early clinker reaction, mixed hydration and carbonation, is now a main ambition of the precast industry. However, before it can be successfully deployed with an increasing variety of SCMs, it is crucial to both quantify the impact of the initial binder composition under various curing conditions and the influence of early age carbonation curing on the late-age properties. The long-term objective of this proposal is to develop a reactive transport model to analyze bulk precast samples produced under mixed hydration-carbonation curing. In this first stage of the SPP, we focus on characterizing the fundamental kinetics of the hydration and carbonation reactions. The general objectives are twofold. Firstly, we aim to create an experimental workflow to quantify the carbon uptake and the phase assemblage of blended system cured in mixed hydration carbonation conditions. The workflow will be tested on synthetic blended system, and validated on blended systems relevant to the partner projects of the SPP. Secondly, this data will be used to develop a kinetic model to predict the phase assemblage evolution as function of cement formulation and curing conditions. The novelty of our approach is to bring and adapt the fundamental characterization techniques that were instrumental in advancing our understanding of the hydration and mineral carbonation process. As such we focus on phase assemblage characterization and pore solution analysis coupled with thermodynamics modelling to identify and analyze the driving factors and propose a mechanistic kinetic model. To bridge our result to the practice, our model will be simplified to a semi-empirical model, so it can be successfully disseminated to the engineering community to optimize the performance of future binder systems. In addition to the model, the outputs of our project are crucial for the SPP, as it provide necessary information for life-cycle analysis. For example, our study of the impact of calcium availability in the system will provide clear experimental data to decide between substitution factor, filler content and the conditions and extent of carbonation curing. This analysis is critical to best use our limited resources while reducing CO2 emissions.

• DFG Programme: Priority Programmes
• Subproject of: SPP 2436: Net-Zero Concrete